path: root/doc/internals.ps

%!PS-Adobe-2.0
%%Creator: dvipsk 5.58f Copyright 1986, 1994 Radical Eye Software
%%Title: diplarb.dvi
%%Pages: 117
%%PageOrder: Ascend
%%BoundingBox: 0 0 596 842
%%DocumentFonts: Times-Roman Courier Times-Bold Times-Italic
%%DocumentPaperSizes: A4
%%EndComments
%DVIPSCommandLine: dvips diplarb.dvi
%DVIPSParameters: dpi=360, comments removed
%DVIPSSource:  TeX output 1998.11.29:1121
%%BeginProcSet: tex.pro
/TeXDict 250 dict def TeXDict begin /N{def}def /B{bind def}N /S{exch}N
/X{S N}B /TR{translate}N /isls false N /vsize 11 72 mul N /hsize 8.5 72
mul N /landplus90{false}def /@rigin{isls{[0 landplus90{1 -1}{-1 1}
ifelse 0 0 0]concat}if 72 Resolution div 72 VResolution div neg scale
isls{landplus90{VResolution 72 div vsize mul 0 exch}{Resolution -72 div
hsize mul 0}ifelse TR}if Resolution VResolution vsize -72 div 1 add mul
TR[matrix currentmatrix{dup dup round sub abs 0.00001 lt{round}if}
forall round exch round exch]setmatrix}N /@landscape{/isls true N}B
/@manualfeed{statusdict /manualfeed true put}B /@copies{/#copies X}B
/FMat[1 0 0 -1 0 0]N /FBB[0 0 0 0]N /nn 0 N /IE 0 N /ctr 0 N /df-tail{
/nn 8 dict N nn begin /FontType 3 N /FontMatrix fntrx N /FontBBox FBB N
string /base X array /BitMaps X /BuildChar{CharBuilder}N /Encoding IE N
end dup{/foo setfont}2 array copy cvx N load 0 nn put /ctr 0 N[}B /df{
/sf 1 N /fntrx FMat N df-tail}B /dfs{div /sf X /fntrx[sf 0 0 sf neg 0 0]
N df-tail}B /E{pop nn dup definefont setfont}B /ch-width{ch-data dup
length 5 sub get}B /ch-height{ch-data dup length 4 sub get}B /ch-xoff{
128 ch-data dup length 3 sub get sub}B /ch-yoff{ch-data dup length 2 sub
get 127 sub}B /ch-dx{ch-data dup length 1 sub get}B /ch-image{ch-data
dup type /stringtype ne{ctr get /ctr ctr 1 add N}if}B /id 0 N /rw 0 N
/rc 0 N /gp 0 N /cp 0 N /G 0 N /sf 0 N /CharBuilder{save 3 1 roll S dup
/base get 2 index get S /BitMaps get S get /ch-data X pop /ctr 0 N ch-dx
0 ch-xoff ch-yoff ch-height sub ch-xoff ch-width add ch-yoff
setcachedevice ch-width ch-height true[1 0 0 -1 -.1 ch-xoff sub ch-yoff
.1 sub]{ch-image}imagemask restore}B /D{/cc X dup type /stringtype ne{]}
if nn /base get cc ctr put nn /BitMaps get S ctr S sf 1 ne{dup dup
length 1 sub dup 2 index S get sf div put}if put /ctr ctr 1 add N}B /I{
cc 1 add D}B /bop{userdict /bop-hook known{bop-hook}if /SI save N @rigin
0 0 moveto /V matrix currentmatrix dup 1 get dup mul exch 0 get dup mul
add .99 lt{/QV}{/RV}ifelse load def pop pop}N /eop{SI restore userdict
/eop-hook known{eop-hook}if showpage}N /@start{userdict /start-hook
known{start-hook}if pop /VResolution X /Resolution X 1000 div /DVImag X
/IE 256 array N 0 1 255{IE S 1 string dup 0 3 index put cvn put}for
65781.76 div /vsize X 65781.76 div /hsize X}N /p{show}N /RMat[1 0 0 -1 0
0]N /BDot 260 string N /rulex 0 N /ruley 0 N /v{/ruley X /rulex X V}B /V
{}B /RV statusdict begin /product where{pop product dup length 7 ge{0 7
getinterval dup(Display)eq exch 0 4 getinterval(NeXT)eq or}{pop false}
ifelse}{false}ifelse end{{gsave TR -.1 .1 TR 1 1 scale rulex ruley false
RMat{BDot}imagemask grestore}}{{gsave TR -.1 .1 TR rulex ruley scale 1 1
false RMat{BDot}imagemask grestore}}ifelse B /QV{gsave newpath transform
round exch round exch itransform moveto rulex 0 rlineto 0 ruley neg
rlineto rulex neg 0 rlineto fill grestore}B /a{moveto}B /delta 0 N /tail
{dup /delta X 0 rmoveto}B /M{S p delta add tail}B /b{S p tail}B /c{-4 M}
B /d{-3 M}B /e{-2 M}B /f{-1 M}B /g{0 M}B /h{1 M}B /i{2 M}B /j{3 M}B /k{
4 M}B /w{0 rmoveto}B /l{p -4 w}B /m{p -3 w}B /n{p -2 w}B /o{p -1 w}B /q{
p 1 w}B /r{p 2 w}B /s{p 3 w}B /t{p 4 w}B /x{0 S rmoveto}B /y{3 2 roll p
a}B /bos{/SS save N}B /eos{SS restore}B end
%%EndProcSet
%%BeginFont: Times-Roman
% @@psencodingfile@{
%   author = "S. Rahtz, P. MacKay, Alan Jeffrey, B. Horn, K. Berry",
%   version = "0.6",
%   date = "22 June 1996",
%   filename = "8r.enc",
%   email = "kb@@mail.tug.org",
%   address = "135 Center Hill Rd. // Plymouth, MA 02360",
%   codetable = "ISO/ASCII",
%   checksum = "119     662    4424",
%   docstring = "Encoding for TrueType or Type 1 fonts to be used with TeX."
% @}
% 
% Idea is to have all the characters normally included in Type 1 fonts
% available for typesetting. This is effectively the characters in Adobe
% Standard Encoding + ISO Latin 1 + extra characters from Lucida.
% 
% Character code assignments were made as follows:
% 
% (1) the Windows ANSI characters are almost all in their Windows ANSI
% positions, because some Windows users cannot easily reencode the
% fonts, and it makes no difference on other systems. The only Windows
% ANSI characters not available are those that make no sense for
% typesetting -- rubout (127 decimal), nobreakspace (160), softhyphen
% (173). quotesingle and grave are moved just because it's such an
% irritation not having them in TeX positions.
% 
% (2) Remaining characters are assigned arbitrarily to the lower part
% of the range, avoiding 0, 10 and 13 in case we meet dumb software.
% 
% (3) Y&Y Lucida Bright includes some extra text characters; in the
% hopes that other PostScript fonts, perhaps created for public
% consumption, will include them, they are included starting at 0x12.
% 
% (4) Remaining positions left undefined are for use in (hopefully)
% upward-compatible revisions, if someday more characters are generally
% available.
% 
% (5) hyphen appears twice for compatibility with both ASCII and Windows.
% 
/TeXBase1Encoding [
% 0x00 (encoded characters from Adobe Standard not in Windows 3.1)
  /.notdef /dotaccent /fi /fl
  /fraction /hungarumlaut /Lslash /lslash
  /ogonek /ring /.notdef
  /breve /minus /.notdef 
% These are the only two remaining unencoded characters, so may as
% well include them.
  /Zcaron /zcaron 
% 0x10
 /caron /dotlessi 
% (unusual TeX characters available in, e.g., Lucida Bright)
 /dotlessj /ff /ffi /ffl 
 /.notdef /.notdef /.notdef /.notdef
 /.notdef /.notdef /.notdef /.notdef
 % very contentious; it's so painful not having quoteleft and quoteright
 % at 96 and 145 that we move the things normally found there down to here.
 /grave /quotesingle 
% 0x20 (ASCII begins)
 /space /exclam /quotedbl /numbersign
 /dollar /percent /ampersand /quoteright
 /parenleft /parenright /asterisk /plus /comma /hyphen /period /slash
% 0x30
 /zero /one /two /three /four /five /six /seven
 /eight /nine /colon /semicolon /less /equal /greater /question
% 0x40
 /at /A /B /C /D /E /F /G /H /I /J /K /L /M /N /O
% 0x50
 /P /Q /R /S /T /U /V /W
 /X /Y /Z /bracketleft /backslash /bracketright /asciicircum /underscore
% 0x60
 /quoteleft /a /b /c /d /e /f /g /h /i /j /k /l /m /n /o
% 0x70
 /p /q /r /s /t /u /v /w
 /x /y /z /braceleft /bar /braceright /asciitilde
 /.notdef % rubout; ASCII ends
% 0x80
 /.notdef /.notdef /quotesinglbase /florin
 /quotedblbase /ellipsis /dagger /daggerdbl
 /circumflex /perthousand /Scaron /guilsinglleft
 /OE /.notdef /.notdef /.notdef
% 0x90
 /.notdef /.notdef /.notdef /quotedblleft
 /quotedblright /bullet /endash /emdash
 /tilde /trademark /scaron /guilsinglright
 /oe /.notdef /.notdef /Ydieresis
% 0xA0
 /.notdef % nobreakspace
 /exclamdown /cent /sterling
 /currency /yen /brokenbar /section
 /dieresis /copyright /ordfeminine /guillemotleft
 /logicalnot
 /hyphen % Y&Y (also at 45); Windows' softhyphen
 /registered
 /macron
% 0xD0
 /degree /plusminus /twosuperior /threesuperior
 /acute /mu /paragraph /periodcentered
 /cedilla /onesuperior /ordmasculine /guillemotright
 /onequarter /onehalf /threequarters /questiondown
% 0xC0
 /Agrave /Aacute /Acircumflex /Atilde /Adieresis /Aring /AE /Ccedilla
 /Egrave /Eacute /Ecircumflex /Edieresis
 /Igrave /Iacute /Icircumflex /Idieresis
% 0xD0
 /Eth /Ntilde /Ograve /Oacute
 /Ocircumflex /Otilde /Odieresis /multiply
 /Oslash /Ugrave /Uacute /Ucircumflex
 /Udieresis /Yacute /Thorn /germandbls
% 0xE0
 /agrave /aacute /acircumflex /atilde
 /adieresis /aring /ae /ccedilla
 /egrave /eacute /ecircumflex /edieresis
 /igrave /iacute /icircumflex /idieresis
% 0xF0
 /eth /ntilde /ograve /oacute
 /ocircumflex /otilde /odieresis /divide
 /oslash /ugrave /uacute /ucircumflex
 /udieresis /yacute /thorn /ydieresis
] def
%%EndFont
%%BeginProcSet: texps.pro
TeXDict begin /rf{findfont dup length 1 add dict begin{1 index /FID ne 2
index /UniqueID ne and{def}{pop pop}ifelse}forall[1 index 0 6 -1 roll
exec 0 exch 5 -1 roll VResolution Resolution div mul neg 0 0]/Metrics
exch def dict begin Encoding{exch dup type /integertype ne{pop pop 1 sub
dup 0 le{pop}{[}ifelse}{FontMatrix 0 get div Metrics 0 get div def}
ifelse}forall Metrics /Metrics currentdict end def[2 index currentdict
end definefont 3 -1 roll makefont /setfont load]cvx def}def
/ObliqueSlant{dup sin S cos div neg}B /SlantFont{4 index mul add}def
/ExtendFont{3 -1 roll mul exch}def /ReEncodeFont{/Encoding exch def}def
end
%%EndProcSet
%%BeginProcSet: special.pro
TeXDict begin /SDict 200 dict N SDict begin /@SpecialDefaults{/hs 612 N
/vs 792 N /ho 0 N /vo 0 N /hsc 1 N /vsc 1 N /ang 0 N /CLIP 0 N /rwiSeen
false N /rhiSeen false N /letter{}N /note{}N /a4{}N /legal{}N}B
/@scaleunit 100 N /@hscale{@scaleunit div /hsc X}B /@vscale{@scaleunit
div /vsc X}B /@hsize{/hs X /CLIP 1 N}B /@vsize{/vs X /CLIP 1 N}B /@clip{
/CLIP 2 N}B /@hoffset{/ho X}B /@voffset{/vo X}B /@angle{/ang X}B /@rwi{
10 div /rwi X /rwiSeen true N}B /@rhi{10 div /rhi X /rhiSeen true N}B
/@llx{/llx X}B /@lly{/lly X}B /@urx{/urx X}B /@ury{/ury X}B /magscale
true def end /@MacSetUp{userdict /md known{userdict /md get type
/dicttype eq{userdict begin md length 10 add md maxlength ge{/md md dup
length 20 add dict copy def}if end md begin /letter{}N /note{}N /legal{}
N /od{txpose 1 0 mtx defaultmatrix dtransform S atan/pa X newpath
clippath mark{transform{itransform moveto}}{transform{itransform lineto}
}{6 -2 roll transform 6 -2 roll transform 6 -2 roll transform{
itransform 6 2 roll itransform 6 2 roll itransform 6 2 roll curveto}}{{
closepath}}pathforall newpath counttomark array astore /gc xdf pop ct 39
0 put 10 fz 0 fs 2 F/|______Courier fnt invertflag{PaintBlack}if}N
/txpose{pxs pys scale ppr aload pop por{noflips{pop S neg S TR pop 1 -1
scale}if xflip yflip and{pop S neg S TR 180 rotate 1 -1 scale ppr 3 get
ppr 1 get neg sub neg ppr 2 get ppr 0 get neg sub neg TR}if xflip yflip
not and{pop S neg S TR pop 180 rotate ppr 3 get ppr 1 get neg sub neg 0
TR}if yflip xflip not and{ppr 1 get neg ppr 0 get neg TR}if}{noflips{TR
pop pop 270 rotate 1 -1 scale}if xflip yflip and{TR pop pop 90 rotate 1
-1 scale ppr 3 get ppr 1 get neg sub neg ppr 2 get ppr 0 get neg sub neg
TR}if xflip yflip not and{TR pop pop 90 rotate ppr 3 get ppr 1 get neg
sub neg 0 TR}if yflip xflip not and{TR pop pop 270 rotate ppr 2 get ppr
0 get neg sub neg 0 S TR}if}ifelse scaleby96{ppr aload pop 4 -1 roll add
2 div 3 1 roll add 2 div 2 copy TR .96 dup scale neg S neg S TR}if}N /cp
{pop pop showpage pm restore}N end}if}if}N /normalscale{Resolution 72
div VResolution 72 div neg scale magscale{DVImag dup scale}if 0 setgray}
N /psfts{S 65781.76 div N}N /startTexFig{/psf$SavedState save N userdict
maxlength dict begin /magscale true def normalscale currentpoint TR
/psf$ury psfts /psf$urx psfts /psf$lly psfts /psf$llx psfts /psf$y psfts
/psf$x psfts currentpoint /psf$cy X /psf$cx X /psf$sx psf$x psf$urx
psf$llx sub div N /psf$sy psf$y psf$ury psf$lly sub div N psf$sx psf$sy
scale psf$cx psf$sx div psf$llx sub psf$cy psf$sy div psf$ury sub TR
/showpage{}N /erasepage{}N /copypage{}N /p 3 def @MacSetUp}N /doclip{
psf$llx psf$lly psf$urx psf$ury currentpoint 6 2 roll newpath 4 copy 4 2
roll moveto 6 -1 roll S lineto S lineto S lineto closepath clip newpath
moveto}N /endTexFig{end psf$SavedState restore}N /@beginspecial{SDict
begin /SpecialSave save N gsave normalscale currentpoint TR
@SpecialDefaults count /ocount X /dcount countdictstack N}N /@setspecial
{CLIP 1 eq{newpath 0 0 moveto hs 0 rlineto 0 vs rlineto hs neg 0 rlineto
closepath clip}if ho vo TR hsc vsc scale ang rotate rwiSeen{rwi urx llx
sub div rhiSeen{rhi ury lly sub div}{dup}ifelse scale llx neg lly neg TR
}{rhiSeen{rhi ury lly sub div dup scale llx neg lly neg TR}if}ifelse
CLIP 2 eq{newpath llx lly moveto urx lly lineto urx ury lineto llx ury
lineto closepath clip}if /showpage{}N /erasepage{}N /copypage{}N newpath
}N /@endspecial{count ocount sub{pop}repeat countdictstack dcount sub{
end}repeat grestore SpecialSave restore end}N /@defspecial{SDict begin}
N /@fedspecial{end}B /li{lineto}B /rl{rlineto}B /rc{rcurveto}B /np{
/SaveX currentpoint /SaveY X N 1 setlinecap newpath}N /st{stroke SaveX
SaveY moveto}N /fil{fill SaveX SaveY moveto}N /ellipse{/endangle X
/startangle X /yrad X /xrad X /savematrix matrix currentmatrix N TR xrad
yrad scale 0 0 1 startangle endangle arc savematrix setmatrix}N end
%%EndProcSet
TeXDict begin 39158280 55380996 1000 360 360 (diplarb.dvi)
@start /Fa 1 106 df<0C0E0C00000000305898983030606464683007127D910D>105
D E /Fb 4 96 df<70000000000EF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000
001FF8000000001FF8000000001FF8000000001FFC000000003F7C000000003E7C000000
003E7E000000007E3E000000007C3F00000000FC1F00000000F81F80000001F80FC00000
03F00FE0000007F007F000000FE003F800001FC001FE00007F8000FF8001FF00007FF00F
FE00003FFFFFFC00000FFFFFF0000007FFFFE0000000FFFF000000001FF8000030467D7F
37>91 D<00001FF800000000FFFF00000007FFFFE000000FFFFFF000003FFFFFFC00007F
F00FFE0000FF8001FF0001FE00007F8003F800001FC007F000000FE00FE0000007F00FC0
000003F01F80000001F81F00000000F83F00000000FC3E000000007C7E000000007E7C00
0000003E7C000000003EFC000000003FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001FF8000000001FF8000000001FF800
0000001FF8000000001FF8000000001FF8000000001F70000000000E30467D7F37>I<00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>94
D<70000000000EF8000000001FF8000000001FF8000000001FFC000000003F7C00000000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>I
E /Fc 1 49 df<060F0F0F1E1E1C3C38383870706060E0C04008127E920B>48
D E /Fd 1 49 df<081C1C3838383070706060C0C0060D7E8D0B>48
D E /Fe 1 50 df<C0000018E0000038F0000078F80000F8DC0001D8CE000398C7000718
C3800E18C1C01C18C0E03818C0707018C038E018C01DC018C00F8018C00F8018C01DC018
C038E018C0707018C0E03818C1C01C18C3800E18C7000718CE000398DC0001D8F80000F8
F0000078E0000038C00000181D1C7D9E24>49 D E /Ff 27 120
df<60F0F06004047C830C>58 D<60F0F07010101020204040040B7C830C>I<0000300000
007000000078000000F8000001F8000001F800000378000003780000067800000E780000
0C780000187C0000183C0000303C0000603C0000603C0000FFFC0000FFFC0001803C0003
003C0003003E0006001E000E001E007F80FFC0FF81FFC01A197E981E>65
D<07FFFE0007FFFF8000F007C000F003C000F001E000F001E001E001C001E003C001E007
8001E00F0003C03E0003FFF80003C01E0003C00F00078007800780078007800780078007
800F000F000F000F000F003E000F007C00FFFFF000FFFFC0001B187E971E>I<000FE040
003FF8C000F81DC001E00780078007800F0003801E0003801C0003003C00030078000300
78000000F0000000F0000000F0000000F0000000F0000000E0000C00E0000C00F0001800
F000180070003000780060003C00C0001F0380000FFF000003F800001A1A7D981D>I<07
FFFE0007FFFF8000F003E000F000F000F0007000F0007801E0007801E0003801E0003801
E0003803C0007803C0007803C0007803C00078078000F0078000F0078001E0078001C00F
0003C00F0007800F000E000F007C00FFFFF000FFFFC0001D187E9721>I<07FFFFE007FF
FFE000F001E000F000C000F000C000F000C001E000C001E030C001E030C001E0700003C0
600003FFE00003FFE00003C0E0000780C1800780C1800780C300078003000F0006000F00
06000F001E000F007C00FFFFFC00FFFFF8001B187E971D>I<03FFC003FF800078000078
0000780000780000F00000F00000F00000F00001E00001E00001E00001E00003C00003C0
0003C00003C0000780000780000780000780007FF000FFF00012187E9712>73
D<07FF8007FF8000F00000F00000F00000F00001E00001E00001E00001E00003C00003C0
0003C00003C00007800C07800C07800C0780180F00180F00380F00700F01F0FFFFE0FFFF
E016187E971B>76 D<07FC0003FC07FC0007FC00FC000FC000DE000FC000DE001BC000DE
0033C0019E003780019E006780019E00C780018F00C780030F018F00030F030F00030F03
0F00030F060F00060F0C1E0006078C1E000607981E000607B01E000C07B03C000C07E03C
000C07C03C001C03C03C00FF8383FF80FF8303FF8026187E9726>I<07F801FF07FC01FF
00FC003800FE003000DE003000CF0030018F006001878060018780600183C0600303E0C0
0301E0C00301F0C00300F0C00600F9800600798006007D8006003D800C003F000C001F00
0C000F001C000F00FF800600FF80060020187E9720>I<07FFFC0007FFFF0000F0078000
F003C000F001C000F001C001E003C001E003C001E003C001E0078003C00F0003C01E0003
FFF80003C00000078000000780000007800000078000000F0000000F0000000F0000000F
000000FFE00000FFE000001A187E9719>80 D<07FFF80007FFFE0000F00F0000F0078000
F0038000F003C001E0078001E0078001E0070001E00E0003C0380003FFE00003C0700003
C0380007803C0007803C0007803C0007803C000F0078000F0078000F0078600F007860FF
E078C0FFE0388000000F001B197E971E>82 D<001F84007FCC01E0FC0380380300380700
380700380F00300F00000F800007F00007FE0003FF8000FFC0001FC00003E00001E00000
E03000E06001C06001C0700380700300FC0E00CFFC0083F000161A7D9818>I<1FFFFFC0
1FFFFFC03C0F03C0300F0180700F0180600F0180601E0180C01E0180C01E0180001E0000
003C0000003C0000003C0000003C00000078000000780000007800000078000000F00000
00F0000000F0000000F000003FFF00003FFF00001A187E9718>I<FFE03FE0FFE03FE01E
0007001E0006001E0006001E0006003C000C003C000C003C000C003C000C007800180078
0018007800180078001800F0003000F0003000F0003000F0006000F0006000F000C000F0
01C000700380003C0E00001FFC000007F000001B197D971B>I<03FF87FC03FF87FC003C
03C0003E0300001E0600001F0E00000F1C00000FB800000FF0000007E0000007C0000003
C0000003E0000007E000000DF0000018F0000030F0000060F80000C0780001807C000300
3C000F003E00FFC0FFC0FFC1FFC01E187E9721>88 D<07980C781878303870386070E070
E070E070C0E1C0E3C0E3C1E663E43C38100F7D8E16>97 D<03E00E301878307870706000
E000E000E000C000C000C010603060E01F800D0F7D8E12>99 D<03E00E30181830187030
E070FFC0E000E000E000E000E010603030E01F800D0F7D8E13>101
D<018003C003800380000000000000000000001C0027004700C700C7000E000E001C001C
001C4038C038C0398039001E000A187E970E>105 D<001C001C003C0018000000000000
0000000001E0033006380C380C38007000700070007000E000E000E000E001C001C001C0
01C06380F380F700E60078000E1F7F9710>I<1F801F8007000700070007000E000E000E
000E0E1C371C4F1C8F1D063A003F003BC038E070E170E370E370E6E064603810187D9715
>I<3C1F00666380478180C781C0C701C00E03800E03800E03800E07001C07081C07181C
0E181C0E303806601803C0150F7E8E19>110 D<3C7C66C7478FC70FC7060E000E000E00
0E001C001C001C001C0038001800100F7E8E12>114 D<03E00C300878187818701F001F
E00FF003F06030F030F030E06060C03F000D0F7D8E13>I<1E0183002303878063038380
C7038380C7038380070703000E0703000E0703000E0703001C0E06001C0E06001C0E0400
0C0E08000617180003E1E000190F7E8E1D>119 D E /Fg 4 62 df<03000F00FF00F700
07000700070007000700070007000700070007000700070007000700070007000700FFF0
FFF00C177D9614>49 D<0F803FE070F06078F83CF83CF83C703C003C00380078007000E0
01C0038003000600080C100C201C7FF8FFF8FFF80E177E9614>I<0F801FE038F0707078
78787878783078007000E001C00F8000E000700038003C703CF83CF83CF838707870F03F
E00F800E187E9614>I<FFFFFF80FFFFFF80000000000000000000000000000000000000
000000000000FFFFFF80FFFFFF80190A7E8D1F>61 D E /Fh 133[27
30 30 43 30 33 20 23 27 1[33 30 33 50 17 33 1[17 33 30
20 27 33 27 33 30 9[60 43 43 40 33 43 47 37 47 43 56
40 2[23 47 47 37 40 43 43 1[43 8[30 30 30 30 30 30 30
30 2[15 20 15 2[20 20 37[33 2[{ TeXBase1Encoding ReEncodeFont }58
60.000002 /Times-Bold rf /Fi 133[32 36 36 52 36 40 24
28 32 1[40 36 40 60 20 2[20 40 36 24 32 40 32 40 36 9[72
1[52 48 40 52 56 44 56 1[68 48 2[28 56 56 44 48 52 52
1[52 8[36 36 36 36 36 36 36 36 1[20 18 1[18 4[24 39[{
 TeXBase1Encoding ReEncodeFont }53 71.999969 /Times-Bold
rf /Fj 139[34 1[46 1[57 7[57 2[46 3[52 29[75 15[52 52
52 49[{ TeXBase1Encoding ReEncodeFont }10 103.700026
/Times-Bold rf /Fk 43 123 df<07FFFFC00FFFFFC01FFFFFC0383060006070C000C0
60C000C060C0000060C00000E1C00000C1C00001C1C00001C1C00001C1C0000381C00003
81C0000781E0000701E0000F01E0000F01F0000E00F0000C00E0001A157F941C>25
D<007FFF8001FFFF8003FFFF800783C0000F01C0001E01E0003C01E0003C01E0007801E0
007801E0007801E000F003C000F003C000F003C000F0078000F0070000700F0000700E00
00301800001870000007C0000019157E941C>27 D<78FCFCFCFC7806067C850E>58
D<78FCFCFEFE7A0202020404040810204007107C850E>I<0000000C0000003C000000F0
000003C000000F0000003C000000F0000003C000000F0000003C000000F0000003C00000
0F0000003C000000F0000000F00000003C0000000F00000003C0000000F00000003C0000
000F00000003C0000000F00000003C0000000F00000003C0000000F00000003C0000000C
1E1E7C9A27>I<C0000000F00000003C0000000F00000003C0000000F00000003C000000
0F00000003C0000000F00000003C0000000F00000003C0000000F00000003C0000003C00
0000F0000003C000000F0000003C000000F0000003C000000F0000003C000000F0000003
C000000F0000003C000000F0000000C00000001E1E7C9A27>62 D<000001C000000001C0
00000003C000000003C000000007C00000000FC00000000FC00000001FC00000001FE000
000037E000000033E000000063E0000000C3E0000000C3E000000183E000000183E00000
0303E000000703E000000603E000000C03E000000C03F000001801F000001801F000003F
FFF000007FFFF000006001F00000C001F00000C001F000018001F000038001F000030001
F000070001F8001F0001F800FFE01FFF80FFC01FFF8021237EA225>65
D<00FFFFFC0000FFFFFF000007C00FC00007C003C0000F8003E0000F8001E0000F8001F0
000F8001F0001F0001E0001F0003E0001F0003E0001F0007C0003E000780003E001F0000
3E003E00003E00F800007FFFF000007C003C00007C001E00007C001F0000F8000F0000F8
000F0000F8000F8000F8000F8001F0000F0001F0001F0001F0001F0001F0003E0003E000
7C0003E0007C0003E001F80007E007E000FFFFFFC000FFFFFE000024227FA126>I<0000
7F00C00003FFC180000FC0E380001F003380007C001F8000F0000F0001E0000F0003C000
0F000780000F000F800006000F000006001F000006003E000006003E00000C007C000000
007C000000007C00000000F800000000F800000000F800000000F800000000F800000000
F000000000F000003000F000003000F000006000F800006000F80000C000780000C00078
000180003C000300001E000600000F001C000007C070000003FFE00000007F0000002224
7DA224>I<00FFFFFC0000FFFFFF800007C00FC00007C003E0000F8001F0000F8000F000
0F800078000F800078001F000078001F00007C001F00007C001F00007C003E00007C003E
00007C003E00007C003E00007C007C000078007C0000F8007C0000F8007C0000F800F800
01F000F80001F000F80001E000F80003E001F00003C001F000078001F0000F8001F0000F
0003E0001E0003E0007C0003E000F00007E007E000FFFFFF8000FFFFFC000026227FA129
>I<00FFFFFFF000FFFFFFF00007C001F00007C000F0000F800070000F800070000F8000
60000F800060001F000060001F006060001F006060001F006060003E00C000003E00C000
003E03C000003FFFC000007FFF8000007C038000007C038000007C03800000F803000000
F80300C000F80300C000F800018001F000018001F000030001F000030001F000070003E0
00060003E0000E0003E0003C0007E000FC00FFFFFFFC00FFFFFFF80024227FA125>I<00
FFFFFFE000FFFFFFE00007C003E00007C001E0000F8000E0000F8000E0000F8000C0000F
8000C0001F0000C0001F0000C0001F00C0C0001F00C0C0003E018000003E018000003E03
8000003E078000007FFF0000007FFF0000007C070000007C07000000F806000000F80600
0000F806000000F806000001F000000001F000000001F000000001F000000003E0000000
03E000000003E000000007E0000000FFFF800000FFFF00000023227EA120>I<007FFE00
FFFE0007C00007C0000F80000F80000F80000F80001F00001F00001F00001F00003E0000
3E00003E00003E00007C00007C00007C00007C0000F80000F80000F80000F80001F00001
F00001F00001F00003E00003E00003E00007E0007FFE00FFFE0017227FA116>73
D<00FFFF0000FFFF000007C0000007C000000F8000000F8000000F8000000F8000001F00
00001F0000001F0000001F0000003E0000003E0000003E0000003E0000007C0000007C00
00007C0000007C000000F8000000F8000C00F8000C00F8001801F0001801F0001801F000
3001F0003003E0007003E000E003E003E007E00FE0FFFFFFC0FFFFFFC01E227FA122>76
D<00FFE00003FF8000FFE00003FF800007E00007F0000007E0000DF000000DE0000FE000
000DE0001BE000000DE0001BE000000DE00033E0000019E00067C0000019E00067C00000
18F000C7C0000018F000C7C0000030F0018F80000030F0030F80000030F0030F80000030
F0060F80000060F0061F00000060F00C1F00000060F0181F0000006078181F000000C078
303E000000C078303E000000C078603E000000C078C03E0000018078C07C000001807980
7C0000018079807C000001807B007C000003007E00F8000003003E00F8000003003C00F8
00000F803C01F80000FFF0383FFF8000FFF0303FFF800031227EA130>I<007FE001FFC0
00FFE003FFC00007F0003C000007F0003800000DF0003000000DF8003000000CF8003000
000CFC00300000187C00600000187C00600000183E00600000183E00600000303F00C000
00301F00C00000301F80C00000300F80C00000600F81800000600FC18000006007C18000
006007E1800000C003E3000000C003E3000000C001F3000000C001F30000018001FE0000
018000FE0000018000FE00000180007E00000300007C00000300007C00000300003C0000
0F80003C00007FF000180000FFF0001800002A227FA128>I<00007F00000003C1E00000
0E007000003C0038000078001C0000E0001E0001E0000E0003C0000F000780000F000F00
000F000F00000F801E00000F803E00000F803E00000F807C00000F807C00000F807C0000
0F80F800001F00F800001F00F800001F00F800001E00F800003E00F000003E00F000007C
00F000007C00F00000F800F00000F000F80001F000780003E000780003C0003800078000
3C000E00001E001C00000F007800000381E0000000FF00000021247DA226>I<00FFFFFC
0000FFFFFF000007C00F800007C003C0000F8003E0000F8001E0000F8001E0000F8001E0
001F0003E0001F0003E0001F0003E0001F0003C0003E0007C0003E000780003E000F0000
3E001E00007C00F800007FFFE000007C000000007C00000000F800000000F800000000F8
00000000F800000001F000000001F000000001F000000001F000000003E000000003E000
000003E000000007E0000000FFFE000000FFFE00000023227FA120>I<00FFFFF00000FF
FFFC000007C03F000007C00F80000F8007C0000F8003C0000F8003C0000F8003C0001F00
07C0001F0007C0001F0007C0001F000F80003E000F00003E001E00003E007800003E01E0
00007FFF0000007C03C000007C01E000007C00F00000F800F80000F800F80000F800F800
00F800F80001F001F00001F001F00001F001F00001F001F00003E003E00003E003E06003
E003E06007E001E0C0FFFE01E0C0FFFE00F1800000003E0023237EA126>82
D<0001F8180007FE30001E0770003C01F0007801F000F000E000E000E001E000E001E000
E003E000C003E000C003E0000003E0000003F0000003FF000001FFE00001FFF80000FFFC
00007FFE00000FFE000000FE0000003F0000001F0000001F0000001F0030001E0030001E
0030001E0030001C0070003C0078003800780070007C00E000EF03C000C3FF800080FE00
001D247DA21F>I<1FFFFFFF1FFFFFFF1F01F01F3C01F0073803E0073003E0077003E006
6003E0066007C006C007C006C007C006C007C006000F8000000F8000000F8000000F8000
001F0000001F0000001F0000001F0000003E0000003E0000003E0000003E0000007C0000
007C0000007C0000007C000000F8000000F8000000F8000001F80000FFFFE000FFFFE000
20227EA11D>I<3FFF00FFE07FFF01FFE003E0001E0003E0001C0007C000180007C00018
0007C000180007C00018000F800030000F800030000F800030000F800030001F00006000
1F000060001F000060001F000060003E0000C0003E0000C0003E0000C0003E0000C0007C
000180007C000180007C000180007C000180007800030000F80003000078000600007800
06000078000C000078001800003C003000001E00E000000F03C0000007FF00000001FC00
000023237EA122>I<007FFE0FFF007FFE0FFF0007F003F00003E001C00003F003800003
F007000001F00E000001F80C000000F818000000FC30000000FC600000007CC00000007F
800000007F800000003F000000003F000000001F000000001F800000003F800000006F80
000000CFC00000018FC000000387C000000707E000000E03E000000C03F000001803F000
003001F000006001F80000C001F80001C000F80007C001FC00FFF00FFFC0FFF00FFFC028
227FA129>88 D<007C6001C6F00303F00601E00E01E01C01E03C01E03803C07803C07803
C07803C0F00780F00780F00784F00786F00F0C700F0C701F083037181867100F81E01715
7E941A>97 D<01E0003FC0003FC00003C00003C0000780000780000780000780000F0000
0F00000F00000F00001E00001E7C001EC6001F03003E03803C03C03C03C03C03C07803C0
7803C07803C07803C0F00780F00780F00780F00F00F00E00701E00701C00303800186000
0F800012237EA215>I<003F0000E1800381C00703C00E07C01C07C03C03803C00007800
00780000780000F00000F00000F00000F000007000407000C03001803807001C1C0007F0
0012157E9416>I<00000F0001FE0001FE00001E00001E00003C00003C00003C00003C00
00780000780000780000780000F0007CF001C6F00303F00601E00E01E01C01E03C01E038
03C07803C07803C07803C0F00780F00780F00784F00786F00F0C700F0C701F0830371818
67100F81E018237EA21A>I<007E000383000701800E01801C0180380180780300700600
FFF800F00000F00000E00000E00000E00000E00000E00080E00180700300300E00183800
0FE00011157D9417>I<007000F800F800F000E000000000000000000000000000000000
0F00118021C061C0C3C0C3C0C3C0078007800F000F000F001E001E101E183C303C303C60
384018C00F000D227FA111>105 D<0078000FF0000FF00000F00000F00001E00001E000
01E00001E00003C00003C00003C00003C00007800007807807818C07821C0F043C0F087C
0F107C0F20381EC0001F00001FF0001E3C003C1E003C1E003C0F083C0F0C781E18781E18
781E10780E30F006206003C016237EA21A>107 D<00F00FE01FE001E001E003C003C003
C003C007800780078007800F000F000F000F001E001E001E001E003C003C003C003C0078
007800788078C0F180F180F180730073001C000C237EA20F>I<1E03F000338C380063D8
1C0063E01E00C3E01E00C3C01E00C3C01E0007803C0007803C0007803C0007803C000F00
78000F0078000F00F0400F00F0601E00F0C01E01E0C01E01E1801E00E1003C00E2001800
3C001B157F941E>110 D<003F0000E1C00380E00700700E00701C00783C00783C007878
0078780078780078F000F0F000F0F000E0F001E07001C0700380300700380E001C3C0007
E00015157E9418>I<03C0F80006718C000C7E06000C7C07001878078018780780187807
8000F0078000F0078000F0078000F0078001E00F0001E00F0001E00F0001E01E0003C01C
0003C03C0003E0380003E0700007B0C000078F000007800000078000000F0000000F0000
000F0000000F0000001E0000001E000000FFE00000FFE00000191F819419>I<007C1001
C6700303F00601E00E01E01C01E03C01E03803C07803C07803C07803C0F00780F00780F0
0780F00780F00F00700F00701F00303F00187E000F9E00001E00001E00003C00003C0000
3C00003C0000780000780007FF8007FF80141F7E9416>I<1F078033984063F0E063E1E0
C3C3E0C3C3E0C3C1C00780000780000780000780000F00000F00000F00000F00001E0000
1E00001E00001E00003C000018000013157F9416>I<007E0000C3000181800303800707
8007078007020007E00007FC0007FE0003FF0001FF80001F80300780780780F80700F807
00F00600600C003038000FE00011157E9417>I<00E001E001E001E001E003C003C003C0
03C00780FFFCFFFC07800F000F000F000F001E001E001E001E003C003C003C083C0C7818
78107830386038C00F000E1F7F9E12>I<0F807019C0F031E0F861E078C1E038C1E038C3
C03803C0300780300780300780300F00600F00600F00400F00C00F00800F01800F010007
0200038C0001F00015157F9418>118 D<0F80180E19C03C1E31E03C1F61E0780FC1E078
07C1E07807C3C0780703C0F0060780F0060780F0060780F0060F01E00C0F01E00C0F01E0
0C0F01E0180F01E0180F01E0100F03E0200702E060038470C000F81F0020157F9424>I<
03E0F00C3318183E1C303E3C203C7C603C7C603C3800780000780000780000780000F000
00F00000F00830F00C79E018F9E018F9E030F360606230C03C1F0016157E941C>I<0F80
0C19C01E31E01E61E03CC1E03CC1E03CC3C03C03C0780780780780780780780F00F00F00
F00F00F00F00F00F01E00F01E00F01E00703E0030FC001F3C00003C00003C00007803C07
007C0F007C0E00781C0060380030E0001F8000171F7F9418>I<00E03003F03007F86007
FFC00C01800C0300000600000C0000180000300000600000C0000180000300400600600C
00C01803C03FFF8071FF0060FE00C0780014157E9417>I E /Fl
14 94 df<00200040008001800300060006000E000C001C001800380038003800700070
0070007000F000F000F000F000F000F000F000F000F000F000F000F000F000F000700070
007000700038003800380018001C000C000E0006000600030001800080004000200B327C
A413>40 D<800040002000300018000C000C000E0006000700030003800380038001C001
C001C001C001E001E001E001E001E001E001E001E001E001E001E001E001E001E001C001
C001C001C00380038003800300070006000E000C000C00180030002000400080000B327D
A413>I<0001800000018000000180000001800000018000000180000001800000018000
0001800000018000000180000001800000018000000180000001800000018000FFFFFFFF
FFFFFFFF0001800000018000000180000001800000018000000180000001800000018000
000180000001800000018000000180000001800000018000000180000001800020227D9C
27>43 D<01F800070E000E07001C03803C03C03801C07801E07801E07801E07801E0F801
F0F801F0F801F0F801F0F801F0F801F0F801F0F801F0F801F0F801F0F801F0F801F0F801
F0F801F07801E07801E07801E07801E03C03C03C03C01C03800E0700070E0001F8001422
7EA019>48 D<00C001C007C0FFC0FBC003C003C003C003C003C003C003C003C003C003C0
03C003C003C003C003C003C003C003C003C003C003C003C003C003C003C003C0FFFFFFFF
10217CA019>I<03F8000FFE001C1F803007C06003C06003E0F801E0FC01F0FC01F0FC01
F07801F03001F00001E00003E00003E00007C0000780000F00000E00001C000038000070
0000E0000180000300300600300400300800701000603FFFE07FFFE0FFFFE0FFFFE01421
7EA019>I<01F8000FFE001E0F803807C03803C07C03E07C03E07C03E03C03E01803E000
03C0000780000780000E00001C0003F800000E000007800003C00003E00001E00001F000
01F03001F07801F0FC01F0FC01F0FC01E0F803E06003C03007801C0F000FFE0003F80014
227EA019>I<000180000380000380000780000F80001F80001780003780006780004780
00C7800187800107800307800607800407800C0780180780300780200780600780C00780
FFFFFCFFFFFC00078000078000078000078000078000078000078000FFFC00FFFC16217F
A019>I<1000401E03801FFF001FFE001FFC001FF0001800001800001800001800001800
0018000018F8001B0E001C07001803801003C00001E00001E00001F00001F00001F07001
F0F801F0F801F0F801F0F801E0C001E06003C07003C03807801C1F000FFC0003F0001422
7EA019>I<003E0000FF8003C1C00780E00F01E01E03E01C03E03C01C03C000078000078
0000780000F8F800F90E00FA0300FC0380FC01C0FC01E0F801E0F801F0F801F0F801F0F8
01F0F801F07801F07801F07801E03801E03C01E01C03C01E03800F0F0003FE0001F80014
227EA019>I<78FCFCFCFC7800000000000000000078FCFCFCFC7806157C940E>58
D<FFFFFFFFFFFFFFFF000000000000000000000000000000000000000000000000000000
0000000000FFFFFFFFFFFFFFFF200C7D9127>61 D<FFFFC0C0C0C0C0C0C0C0C0C0C0C0C0
C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0FFFF0831
7CA40E>91 D<FFFF03030303030303030303030303030303030303030303030303030303
0303030303030303030303030303030303FFFF08317FA40E>93 D
E /Fm 165[30 1[36 47 36 36 30 28 33 36 28 36 36 44 30
2[17 36 36 28 30 36 33 1[36 8[25 25 25 25 25 25 25 25
1[14 12 1[12 4[17 39[{ .167 SlantFont TeXBase1Encoding ReEncodeFont }34
50.000002 /Times-Roman rf /Fn 105[25 27[22 25 25 36 25
28 17 19 22 28 28 25 28 41 14 28 1[14 28 25 17 22 28
22 28 25 10[36 36 33 28 36 39 30 39 36 47 33 39 25 19
39 39 30 33 36 36 1[36 6[17 25 25 25 25 25 25 25 25 25
25 14 12 1[12 2[17 17 17 36[28 2[{ TeXBase1Encoding ReEncodeFont }65
50.000002 /Times-Bold rf /Fo 22 111 df<FFFFFFFCFFFFFFFC1E027C8C27>0
D<C00003E0000770000E38001C1C00380E00700700E00381C001C38000E700007E00003C
00003C00007E0000E70001C3800381C00700E00E00701C003838001C70000EE00007C000
031818799727>2 D<00C00000E00000C00000C00040C080E0C1C0F8C7C07CCF801EDE00
03F00000C00003F0001EDE007CCF80F8C7C0E0C1C040C08000C00000C00000E00000C000
12157D9619>I[<00038000000FE000000FE000000FE000000FE000000FE0000003800000
0000000000000000000000000000000000000000000000FFFFFFFEFFFFFFFE0000000000
0000000000000000000000000000000000000000038000000FE000000FE000000FE00000
0FE000000FE00000038000>31 28 125 153 38 I<03F0000FFC001FFE003FFF007FFF80
7FFF80FFFFC0FFFFC0FFFFC0FFFFC0FFFFC0FFFFC0FFFFC0FFFFC07FFF807FFF803FFF00
1FFE000FFC0003F00012147D9519>15 D<001FFFFC00FFFFFC01E00000078000000E0000
001C0000003800000030000000700000006000000060000000E0000000C0000000C00000
00C0000000C0000000C0000000C0000000E0000000600000006000000070000000300000
00380000001C0000000E0000000780000001E0000000FFFFFC001FFFFC00000000000000
000000000000000000000000000000000000000000000000007FFFFFFC7FFFFFFC1E287C
9F27>18 D<0000000C0000003C000000F0000003C000000F0000003C000000F0000003C0
00000F0000003C000000F0000003C000000F0000003C000000F0000000F00000003C0000
000F00000003C0000000F00000003C0000000F00000003C0000000F00000003C0000000F
00000003C0000000F00000003C0000000C00000000000000000000000000000000000000
00000000000000000000000000FFFFFFFCFFFFFFFC1E287C9F27>20
D<C0000000F00000003C0000000F00000003C0000000F00000003C0000000F00000003C0
000000F00000003C0000000F00000003C0000000F00000003C0000003C000000F0000003
C000000F0000003C000000F0000003C000000F0000003C000000F0000003C000000F0000
003C000000F0000000C00000000000000000000000000000000000000000000000000000
000000000000000000FFFFFFFCFFFFFFFC1E287C9F27>I<000000600000000000300000
0000003000000000001800000000001800000000000C0000000000060000000000030000
FFFFFFFF8000FFFFFFFFE000000000007000000000001C00000000000F800000000003E0
000000000780000000001E00000000003800000000006000FFFFFFFFC000FFFFFFFF8000
0000000300000000000600000000000C0000000000180000000000180000000000300000
0000003000000000006000002B1C7D9932>41 D<001FFF00FFFF01E0000780000E00001C
0000380000300000700000600000600000E00000C00000C00000FFFFFFFFFFFFC00000C0
0000E000006000006000007000003000003800001C00000E000007800001E00000FFFF00
1FFF181E7C9A21>50 D<00000300000300000700000600000E00000C00001C0000180000
380000300000700000600000E00000C00001C0000180000380000300000700000600000E
00000C00001C0000180000180000380000300000700000600000E00000C00001C0000180
000380000300000700000600000E00000C00001C00001800003800003000007000006000
00E00000C00000C00000183079A300>54 D<C0000030C0000030E0000070600000607000
00E0300000C0300000C0380001C018000180180001801C0003800C0003000E00070007FF
FE0007FFFE0007000E0003000C0003000C0003801C000180180001C0380000C0300000C0
300000E07000006060000070E0000030C0000030C0000039C0000019800000198000001F
8000000F0000000F000000060000000600001C2480A21D>56 D<FFFFF8FFFFF800001800
001800001800001800001800001800001800001800001800001800001800001800001800
00183FFFF87FFFF800001800001800001800001800001800001800001800001800001800
0018000018000018000018000018000018FFFFF8FFFFF815237DA21C>I<FFFFFFC0FFFF
FFC0000000C0000000C0000000C0000000C0000000C0000000C0000000C0000000C00000
00C0000000C0000000C01A0D7D9121>I<C00000C0C00000C0C00000C0C00000C0C00000
C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000
C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000
C0E00001C06000018070000380380007001C000E000F807C0003FFF000007F80001A1F7D
9D21>91 D<007F800003FFF0000F807C001C000E00380007007000038060000180E00001
C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000
C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000C0C00000
C0C00000C0C00000C0C00000C0C00000C0C00000C01A1F7D9D21>I<000C0000000C0000
001E0000001E0000003F00000033000000330000007380000061800000E1C00000C0C000
01C0E000018060000180600003807000030030000700380006001800060018000E001C00
0C000C001C000E00180006003800070030000300300003007000038060000180E00001C0
C00000C0C00000C01A1F7D9D21>94 D<C00000C0C00000C0E00001C06000018070000380
300003003000030038000700180006001C000E000C000C000E001C000600180006001800
070038000300300003807000018060000180600001C0E00000C0C00000E1C00000618000
007380000033000000330000003F0000001E0000001E0000000C0000000C00001A1F7D9D
21>I<0007C0003E0000780000F00001E00001E00001E00001E00001E00001E00001E000
01E00001E00001E00001E00001E00001E00001E00001E00001E00001E00003C000078000
1F0000F800001F000007800003C00001E00001E00001E00001E00001E00001E00001E000
01E00001E00001E00001E00001E00001E00001E00001E00001E00001E00000F000007800
003E000007C012317DA419>102 D<F800001F000007800003C00001E00001E00001E000
01E00001E00001E00001E00001E00001E00001E00001E00001E00001E00001E00001E000
01E00001E00000F000007800003E000007C0003E0000780000F00001E00001E00001E000
01E00001E00001E00001E00001E00001E00001E00001E00001E00001E00001E00001E000
01E00001E00003C0000780001F0000F8000012317DA419>I<C0C0C0C0C0C0C0C0C0C0C0
C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0C0
C0C002317AA40E>106 D<C00000C00000E0000060000060000070000030000030000038
00001800001800001C00000C00000C00000E000006000006000007000003000003000003
800001800001800001C00000C00000E00000600000600000700000300000300000380000
1800001800001C00000C00000C00000E0000060000060000070000030000030000038000
01800001800001C00000C00000C012317DA419>110 D E /Fp 133[19
22 22 33 22 25 14 19 19 25 25 25 25 36 14 22 14 14 25
25 14 22 25 22 25 25 9[41 30 36 28 25 30 36 30 36 33
41 28 33 1[17 36 36 30 30 36 33 30 30 3[34 3[25 6[25
25 1[14 12 17 12 2[17 17 17 36[25 2[{ TeXBase1Encoding ReEncodeFont }60
50.000002 /Times-Italic rf /Fq 134[62 1[89 1[69 41 48
55 1[69 62 69 103 34 2[34 69 62 41 55 1[55 69 62 10[89
89 1[69 1[96 76 3[83 5[76 2[89 83 89 25[41 39[{
 TeXBase1Encoding ReEncodeFont }30 124.400017 /Times-Bold
rf /Fr 119[30 10[30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 1[30
1[30 30 30 1[30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 33[{ TeXBase1Encoding ReEncodeFont }91
50.000002 /Courier rf /Fs 134[30 2[30 1[17 23 20 2[30
30 47 17 2[17 1[30 20 27 2[30 27 11[43 1[33 2[33 43 43
53 1[43 3[43 2[43 2[43 7[30 30 5[30 30 2[15 1[15 44[{
 TeXBase1Encoding ReEncodeFont }31 60.000002 /Times-Roman
rf /Ft 87[17 19[22 25[22 25 25 36 25 25 14 19 17 25 25
25 25 39 14 25 14 14 25 25 17 22 25 22 25 22 3[17 1[17
1[36 36 47 36 36 30 28 33 36 28 36 36 44 30 36 19 17
36 36 28 30 36 33 33 36 1[22 1[28 1[14 14 25 25 25 25
25 25 25 25 25 25 14 12 17 12 28 25 17 17 17 2[25 2[17
29[28 28 2[{ TeXBase1Encoding ReEncodeFont }82 50.000002
/Times-Roman rf /Fu 139[24 33 29 1[43 43 43 67 24 2[24
43 43 29 38 1[38 1[38 13[48 1[62 48 1[62 1[53 2[29 3[53
3[62 65[{ TeXBase1Encoding ReEncodeFont }23 86.399998
/Times-Roman rf /Fv 139[20 1[24 1[36 36 1[56 20 2[20
3[32 2[36 32 28[52 68[{ TeXBase1Encoding ReEncodeFont }11
71.999969 /Times-Roman rf end
%%EndProlog
%%BeginSetup
%%Feature: *Resolution 360dpi
TeXDict begin
%%PaperSize: A4

%%EndSetup
%%Page: 1 1
1 0 bop 907 899 a Fv(Diplomarbeit)221 1151 y Fu(Enhancement)22
b(of)f(the)h(ANSI)f(SQL)g(Implementation)h(of)888 1260
y(PostgreSQL)629 1492 y Ft(ausgef)t(\250)-21 b(uhrt)12
b(am)g(Institut)g(f)t(\250)-21 b(ur)11 b(Informationssysteme)761
1552 y(der)h(T)m(echnischen)h(Uni)o(v)o(ersit)s(\250)-20
b(at)11 b(W)n(ien)860 1612 y(unter)h(der)g(Anleitung)f(v)o(on)726
1771 y Fs(O.Uni)o(v)l(.Prof.Dr)m(.)17 b(Geor)o(g)d(Gottlob)1061
1831 y Ft(und)762 1891 y Fs(Uni)o(v)l(.Ass.)k(Mag.)g(Katrin)c(Se)o(yr)
671 1950 y Ft(als)f(v)o(erantwortlicher)d(Uni)o(v)o(ersit)s(\250)-20
b(atsassistentin)1041 2110 y(durch)859 2269 y Fr(Stefan)29
b(Simkovics)814 2329 y(Paul)h(Petersgasse)e(36)799 2389
y(A)i(-)g(2384)f(Breitenfurt)244 2749 y Fs(No)o(v)o(ember)14
b(29,)g(1998)p 244 2766 475 2 v 414 2819 a Ft(Datum)p
1431 2730 567 2 v 1594 2800 a(Unterschrift)p eop
%%Page: 2 2
2 1 bop eop
%%Page: 3 3
3 2 bop 198 633 a Fq(Abstract)198 892 y Ft(PostgreSQL)14
b(is)i(an)f Fp(object-r)n(elational)f Ft(database)h(management)g
(system)g(that)g(runs)f(on)h(almost)g(an)o(y)198 951
y(UNIX)g(based)i(operating)e(system)h(and)g(is)g(distrib)o(uted)f(as)h
(C-source)g(code.)26 b(It)15 b(is)h(neither)f Fp(fr)n(ee)o(war)n(e)198
1011 y Ft(nor)f Fp(public)h(domain)f Ft(software.)23
b(It)14 b(is)h(copyrighted)e(by)i(the)g(Uni)o(v)o(ersity)f(of)h
(California)f(b)o(ut)g(may)h(be)198 1071 y(used,)e(modi\002ed)e(and)i
(distrib)o(uted)e(as)i(long)f(as)g(the)h(licensing)f(terms)g(of)f(the)i
(copyright)d(are)i(accepted.)273 1131 y(As)g(the)f(name)g(already)h
(suggests,)h(PostgreSQL)e(uses)h(an)g(e)o(xtended)f(subset)h(of)f(the)h
(SQL92)f(stan-)198 1191 y(dard)17 b(as)i(the)f(query)f(language.)32
b(At)18 b(the)g(time)f(of)h(writing)f(this)h(document)f(the)h(actual)g
(v)o(ersion)g(of)198 1250 y(PostgreSQL)11 b(was)h(v6.3.2.)k(In)11
b(this)h(v)o(ersion)g(the)f(implemented)g(part)g(of)g(SQL)h(did)f(not)h
(support)f(some)198 1310 y(important)e(features)g(included)h(in)g(the)g
(SQL92)g(standard.)k(T)l(wo)c(of)g(the)g(not)f(supported)h(features)f
(were:)273 1410 y Fo(\017)25 b Ft(the)12 b Fp(having)g(clause)273
1509 y Fo(\017)25 b Ft(the)12 b(support)g(of)g(the)g(set)h(theoretic)f
(operations)g Fp(intersect)g Ft(and)g Fp(e)o(xcept)198
1609 y Ft(It)e(was)g(the)h(author')m(s)f(task)g(to)g(add)h(the)f
(support)g(for)g(the)g(two)f(missing)i(features)f(to)g(the)h(e)o
(xisting)f(source)198 1669 y(code.)22 b(Before)14 b(the)g
(implementation)g(could)g(be)g(started)h(an)f(intensi)o(v)o(e)h(study)f
(of)g(the)g Fp(r)n(ele)o(vant)i(parts)198 1729 y(of)d(the)g(SQL92)f
(standar)n(d)h Ft(and)g(the)g(implementation)f(of)g(the)h
Fp(e)o(xisting)g(featur)n(es)h Ft(of)f(PostgreSQL)f(had)198
1788 y(been)h(necessary)m(.)19 b(This)13 b(document)g(will)g(not)g
(present)g(only)f(the)h(results)h(of)e(the)h(implementation)f(b)o(ut)
198 1848 y(also)h(the)h(kno)o(wledge)e(collected)h(while)g(studying)g
(the)g(SQL)g(language)h(and)f(the)g(source)g(code)g(of)g(the)198
1908 y(already)f(e)o(xisting)h(features.)273 1968 y(Chapter)i(1)h
(presents)h(an)f(o)o(v)o(ervie)o(w)f(on)h(the)g(SQL92)g(standard.)26
b(It)16 b(gi)o(v)o(es)g(a)g(description)g(of)f(the)198
2027 y Fp(r)n(elational)k(data)f(model)h Ft(and)g(the)g(theoretical)g
(\(mathematical\))e(background)i(of)f(SQL.)i(Ne)o(xt)f(the)198
2087 y(SQL)13 b(language)g(itself)f(is)h(described.)18
b(The)13 b(most)g(important)e(SQL)i(statements)h(are)e(presented)h(and)
g(a)198 2147 y(lot)d(of)g(e)o(xamples)h(are)f(included)h(for)e(better)h
(understanding.)15 b(The)c(information)d(gi)o(v)o(en)j(in)f(this)g
(chapter)198 2207 y(has)j(mainly)f(been)g(taken)g(form)f(the)i(books)f
([D)n(A)-6 b(TE96)q(],)12 b([D)n(A)-6 b(TE94)q(])12 b(and)g([ULL88)q
(].)273 2267 y(Chapter)18 b(2)g(gi)o(v)o(es)g(a)h(description)e(on)h
(ho)o(w)g(to)g(use)h(PostgreSQL.)f(First)g(it)g(is)g(sho)o(wn)g(ho)o(w)
g(the)198 2326 y Fp(bac)o(kend)e Ft(\(serv)o(er\))g(can)h(be)g(started)
g(and)f(ho)o(w)h(a)g(connection)f(from)g(a)h(client)f(to)h(the)f(serv)o
(er)h(can)g(be)198 2386 y(established.)f(Ne)o(xt)c(some)g(basic)h
(database)f(management)g(tasks)h(like)e(creating)g(a)h(database,)i
(creating)198 2446 y(a)g(table)f(etc.)19 b(are)14 b(described.)19
b(Finally)12 b(some)i(of)f(PostgreSQL)-5 b(')m(s)14 b(special)g
(features)f(like)g Fp(user)h(de\002ned)198 2506 y(functions)p
Ft(,)d Fp(user)h(de\002ned)f(types)p Ft(,)h(the)f Fp(rule)g(system)h
Ft(etc.)j(are)c(presented)g(and)g(illustrated)f(using)h(a)g(lot)g(of)
198 2565 y(e)o(xamples.)16 b(The)d(information)d(gi)o(v)o(en)i(in)g
(chapter)g(2)g(has)g(mainly)g(been)g(taken)f(from)g(the)h(PostgreSQL)
198 2625 y(documentation)17 b(\(see)i([LOCK98)o(]\),)h(the)e
(PostgreSQL)f(manual)h(pages)h(and)f(was)g(v)o(eri\002ed)f(by)h(the)198
2685 y(author)12 b(throughout)f(v)o(arious)h(e)o(xamples)h(which)f(ha)o
(v)o(e)g(also)h(been)g(included.)273 2745 y(Chapter)h(3)g(concentrates)
h(on)f(the)h(internal)e(structure)h(of)g(the)h(PostgreSQL)f
Fp(bac)o(kend)p Ft(.)21 b(First)14 b(the)198 2804 y(stages)19
b(that)g(a)g(query)f(has)h(to)f(pass)h(in)g(order)f(to)g(retrie)o(v)o
(e)g(a)h(result)f(are)g(described)h(using)f(a)h(lot)g(of)198
2864 y(\002gures)h(to)f(illustrate)g(the)h(in)n(v)o(olv)o(ed)g(data)g
(structures.)38 b(The)20 b(information)e(gi)o(v)o(en)i(in)f(that)h
(part)g(of)198 2924 y(chapter)e(3)h(has)g(been)g(collected)g(while)f
(intensi)o(v)o(ely)h(studying)f(the)h(source)f(code)h(of)f(the)h(rele)o
(v)o(ant)198 2984 y(parts)13 b(of)g(PostgreSQL.)g(This)h(intensi)o(v)o
(e)f(and)g(detailed)g(e)o(xamination)g(of)f(the)h(source)h(code)f(had)g
(been)198 3044 y(necessary)h(to)f(be)g(able)g(to)g(add)g(the)g(missing)
h(functionality)m(.)i(The)e(kno)o(wledge)f(gathered)f(during)g(that)198
3103 y(period)h(of)h(time)f(has)i(been)f(summarized)f(here)h(in)g
(order)f(to)g(make)h(it)f(easier)i(for)e(programmers)f(who)198
3163 y(are)g(ne)o(w)g(to)h(PostgreSQL)f(to)g(\002nd)g(their)g(way)g
(in.)273 3223 y(The)f(follo)o(wing)f(sections)i(co)o(v)o(er)f(the)g
(author')m(s)g(ideas)h(for)e(the)h(implementation)f(of)h(the)g(two)f
(miss-)198 3283 y(ing)i(SQL)h(features)f(mentioned)g(abo)o(v)o(e)g(and)
h(a)f(description)g(of)g(the)g(implementation)g(itself.)273
3342 y(Section)e(3.7)h(deals)h(with)e(the)h(implementation)e(of)i(the)g
Fp(having)f(logic)p Ft(.)15 b(As)c(mentioned)f(earlier)g(the)198
3402 y Fp(having)15 b(logic)f Ft(is)i(one)f(of)f(the)h(two)g(missing)g
(SQL92)g(features)g(that)g(the)g(author)f(had)i(to)e(implement.)1086
3552 y(3)p eop
%%Page: 4 4
4 3 bop 270 60 a Ft(4)270 234 y(The)13 b(\002rst)g(parts)g(of)f(the)h
(chapter)f(describe)h(ho)o(w)g Fp(aggr)n(e)n(gate)f(functions)g
Ft(are)h(realized)g(in)f(PostgreSQL)270 294 y(and)e(after)e(that)i(a)f
(description)g(of)g(the)h(enhancements)g(applied)f(to)g(the)h(code)f
(of)h(the)f Fp(planner/optimizer)270 354 y Ft(and)14
b(the)f Fp(e)o(xecutor)i Ft(in)e(order)g(to)g(realize)h(the)g(ne)o(w)f
(functionality)f(is)i(gi)o(v)o(en.)20 b(The)14 b(functions)f(and)h
(data)270 413 y(structures)e(used)h(and)f(added)h(to)f(the)g(source)h
(code)f(are)g(also)h(handled)f(here.)345 473 y(Section)19
b(3.8)i(deals)g(with)e(the)i(implementation)e(of)g(the)h
Fp(intersect)h Ft(and)f Fp(e)o(xcept)g Ft(functionality)270
533 y(which)d(was)h(the)f(second)h(missing)f(SQL92)g(feature)g(that)g
(had)h(to)f(be)g(added)h(by)f(the)g(author)m(.)31 b(First)270
593 y(a)13 b(theoretical)f(description)g(of)g(the)h(basic)g(idea)g(is)g
(gi)o(v)o(en.)j(The)d Fp(intersect)g Ft(and)g Fp(e)o(xcept)g
Ft(logic)f(is)h(imple-)270 653 y(mented)i(using)f(a)i
Fp(query)f(r)n(e)o(write)h Ft(technique)f(\(i.e.)23 b(a)15
b(query)g(in)n(v)o(olving)f(an)h Fp(intersect)g Ft(and/or)f
Fp(e)o(xcept)270 712 y Ft(operation)h(is)h Fp(r)n(e)o(written)h
Ft(to)f(a)g(semantically)g(equi)o(v)o(alent)f(form)g(that)g(does)i(not)
e(use)h(these)h Fp(set)f(oper)o(-)270 772 y(ations)e
Ft(an)o(y)h(more\).)21 b(After)14 b(presenting)g(the)g(basic)h(idea)g
(the)f(changes)h(made)g(to)f(the)h Fp(parser)g Ft(and)f(the)270
832 y Fp(r)n(e)o(write)g(system)f Ft(are)f(described)h(and)f(the)g
(added)h(functions)f(and)g(data)g(structures)h(are)f(presented.)p
eop
%%Page: 5 5
5 4 bop 198 633 a Fq(Contents)198 943 y Fn(1)50 b(SQL)1600
b(9)273 1003 y Ft(1.1)52 b(The)13 b(Relational)f(Data)h(Model)27
b(.)e(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(10)387 1063 y(1.1.1)61
b(F)o(ormal)11 b(Notion)h(of)g(the)g(Relational)h(Data)f(Model)47
b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(10)547 1123 y(Domains)12 b(vs.)k(Data)d(T)l(ypes)35
b(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)h(.)f(.)g(.)h(.)44 b(11)273 1184 y(1.2)52 b(Operations)12
b(in)h(the)f(Relational)g(Data)h(Model)22 b(.)k(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(11)387
1244 y(1.2.1)61 b(Relational)12 b(Algebra)33 b(.)25 b(.)g(.)h(.)f(.)g
(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)
f(.)g(.)h(.)44 b(11)387 1304 y(1.2.2)61 b(Relational)12
b(Calculus)20 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(14)547 1364 y(T)n(uple)12 b(Relational)g(Calculus)43
b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(14)387 1425 y(1.2.3)61 b(Relational)12
b(Algebra)g(vs.)k(Relational)c(Calculus)43 b(.)26 b(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(14)273 1485 y(1.3)52
b(The)13 b(SQL)g(Language)28 b(.)e(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)
g(.)h(.)44 b(14)387 1545 y(1.3.1)61 b(Select)27 b(.)e(.)h(.)f(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(15)547 1605
y(Simple)11 b(Selects)42 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)
44 b(15)547 1665 y(Joins)j(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(16)547 1726 y(Aggre)o(gate)12
b(Operators)32 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(17)547
1786 y(Aggre)o(gation)11 b(by)h(Groups)k(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(17)547 1846 y(Ha)o(ving)c(.)26 b(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
h(.)f(.)g(.)h(.)44 b(19)547 1906 y(Subqueries)39 b(.)26
b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(19)547
1967 y(Union,)12 b(Intersect,)h(Except)39 b(.)25 b(.)g(.)h(.)f(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(20)387 2027 y(1.3.2)61 b(Data)12 b(De\002nition)27
b(.)e(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(21)547
2087 y(Create)12 b(T)l(able)48 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)
g(.)h(.)44 b(21)547 2147 y(Data)12 b(T)l(ypes)h(in)g(SQL)29
b(.)c(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(21)547 2208 y(Create)12
b(Inde)o(x)44 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(22)547 2268 y(Create)12 b(V)m(ie)o(w)j(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(22)547 2328 y(Drop)12 b(T)l(able,)h(Drop)f
(Inde)o(x,)g(Drop)g(V)m(ie)o(w)27 b(.)e(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(23)387 2388 y(1.3.3)61
b(Data)12 b(Manipulation)36 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)
g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(23)547 2449 y(Insert)12 b(Into)17 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)44 b(23)547 2509 y(Update)e(.)26
b(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(24)547 2569 y(Delete)19 b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(24)387 2629 y(1.3.4)61 b(System)12
b(Catalogs)40 b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(24)387 2690 y(1.3.5)61 b(Embedded)12 b(SQL)17 b(.)25
b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(24)198 2800
y Fn(2)50 b(P)o(ostgr)o(eSQL)12 b(fr)o(om)h(the)f(User')n(s)h(P)o(oint)
f(of)g(V)n(iew)778 b(26)273 2860 y Ft(2.1)52 b(A)13 b(Short)e(History)h
(of)g(PostgreSQL)k(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(26)273
2920 y(2.2)52 b(An)13 b(Ov)o(ervie)o(w)e(on)i(the)f(Features)g(of)g
(PostgreSQL)49 b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f
(.)g(.)h(.)44 b(26)273 2981 y(2.3)52 b(Where)12 b(to)h(Get)f
(PostgreSQL)46 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(27)547 3041 y(Copyright)11 b(of)h(PostgreSQL)48 b(.)25
b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h
(.)f(.)g(.)h(.)44 b(27)547 3101 y(Support)11 b(for)g(PostgreSQL)39
b(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)h(.)f(.)g(.)h(.)44 b(27)273 3161 y(2.4)52 b(Ho)o(w)12
b(to)h(use)f(PostgreSQL)i(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)
f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(28)387 3222 y(2.4.1)61 b(Starting)11 b(The)i(Postmaster)44
b(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)h(.)f(.)g(.)h(.)44 b(28)387 3282 y(2.4.2)61 b(Creating)12
b(a)g(Ne)o(w)h(Database)k(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(28)387
3342 y(2.4.3)61 b(Connecting)12 b(T)l(o)h(a)f(Database)38
b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(29)387 3402 y(2.4.4)61 b(De\002ning)11
b(and)i(Populating)e(T)l(ables)45 b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(29)1086
3552 y(5)p eop
%%Page: 6 6
6 5 bop 270 60 a Ft(6)1515 b Fm(CONTENTS)459 234 y Ft(2.4.5)61
b(Retrie)o(ving)11 b(Data)i(From)e(The)i(Database)27
b(.)e(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(30)345 294 y(2.5)52 b(Some)12 b(of)g(PostgreSQL)-5
b(')m(s)13 b(Special)f(Features)g(in)g(Detail)41 b(.)25
b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(31)459 354 y(2.5.1)61 b(Inheritance)36 b(.)26 b(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)h(.)f(.)g(.)h(.)44 b(31)459 413 y(2.5.2)61 b(User)12
b(De\002ned)g(Functions)g(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)
g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(33)619 473 y(Query)12 b(Language)g(\(SQL\))g(Functions)28
b(.)d(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h
(.)44 b(33)619 533 y(Programming)10 b(Language)j(Functions)18
b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)
h(.)44 b(35)459 593 y(2.5.3)61 b(User)12 b(De\002ned)g(T)l(ypes)18
b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(36)459 653 y(2.5.4)61
b(Extending)12 b(Operators)34 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(39)459 712 y(2.5.5)61 b(Extending)12 b(Aggre)o(gates)42
b(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(40)459 772 y(2.5.6)61
b(T)n(riggers)19 b(.)26 b(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)
g(.)h(.)44 b(43)459 832 y(2.5.7)61 b(Serv)o(er)11 b(Programming)g
(Interface)g(\(SPI\))23 b(.)i(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)44 b(46)459 892 y(2.5.8)61 b(Rules)13
b(in)f(PostgreSQL)27 b(.)e(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(49)270 1001 y Fn(3)50 b(P)o(ostgr)o(eSQL)12 b(fr)o(om)h(the)f(Pr)o
(ogrammer')n(s)i(P)o(oint)e(of)g(V)n(iew)602 b(51)345
1061 y Ft(3.1)52 b(The)13 b(W)l(ay)g(of)f(a)g(Query)j(.)26
b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(51)345
1121 y(3.2)52 b(Ho)o(w)12 b(Connections)h(are)f(Established)48
b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(52)345 1181 y(3.3)52 b(The)13
b(P)o(arser)f(Stage)47 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)
g(.)h(.)44 b(52)459 1240 y(3.3.1)61 b(P)o(arser)25 b(.)g(.)h(.)f(.)h(.)
f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(53)459
1300 y(3.3.2)61 b(T)n(ransformation)11 b(Process)i(.)26
b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)44 b(54)345 1360 y(3.4)52 b(The)13
b(PostgreSQL)f(Rule)h(System)45 b(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)
h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(58)459 1420 y(3.4.1)61 b(The)13 b(Re)o(write)f(System)42
b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(58)619 1479 y(T)m(echniques)12
b(T)l(o)h(Implement)e(V)m(ie)o(ws)19 b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(58)345
1539 y(3.5)52 b(Planner/Optimizer)14 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)h(.)f(.)g(.)h(.)44 b(59)459 1599 y(3.5.1)61 b(Generating)11
b(Possible)i(Plans)40 b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(59)459
1659 y(3.5.2)61 b(Data)12 b(Structure)f(of)h(the)h(Plan)42
b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(59)345 1719 y(3.6)52 b(Ex)o(ecutor)18
b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g
(.)h(.)44 b(60)345 1778 y(3.7)52 b(The)13 b(Realization)g(of)e(the)i
(Ha)o(ving)f(Clause)45 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(62)459 1838 y(3.7.1)61
b(Ho)o(w)12 b(Aggre)o(gate)g(Functions)g(are)g(Implemented)23
b(.)j(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(62)619 1898 y(The)13 b(P)o(arser)f(Stage)36 b(.)26
b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(62)619 1958 y(The)13
b(Re)o(write)f(System)42 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(63)619 2017 y(Planner/Optimizer)d(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)
44 b(63)619 2077 y(Ex)o(ecutor)h(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
h(.)f(.)g(.)h(.)44 b(65)459 2137 y(3.7.2)61 b(Ho)o(w)12
b(the)g(Ha)o(ving)g(Clause)h(is)g(Implemented)25 b(.)g(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(66)619 2197
y(The)13 b(P)o(arser)f(Stage)36 b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h
(.)44 b(66)619 2257 y(The)13 b(Re)o(write)f(System)42
b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(68)619 2316 y(Planner/Optimizer)d
(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(80)619 2376 y(Ex)o(ecutor)h(.)
25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)
g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(87)345 2436 y(3.8)52 b(The)13 b(Realization)g(of)e(Union,)i
(Intersect)f(and)g(Except)43 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)h(.)f(.)g(.)h(.)44 b(89)459 2496 y(3.8.1)61 b(Ho)o(w)12
b(Unions)g(ha)o(v)o(e)h(been)f(Realized)h(Until)f(V)-6
b(ersion)13 b(6.3.2)42 b(.)25 b(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(91)619 2555 y(The)13 b(P)o(arser)f(Stage)36 b(.)26
b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(91)619 2615 y(The)13
b(Re)o(write)f(System)42 b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(92)619 2675 y(Planner/Optimizer)d(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)h
(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)
44 b(92)619 2735 y(Ex)o(ecutor)h(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
h(.)f(.)g(.)h(.)44 b(93)459 2795 y(3.8.2)61 b(Ho)o(w)12
b(Intersect,)g(Except)h(and)f(Union)g(W)l(ork)g(T)l(ogether)34
b(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(93)619
2854 y(Set)12 b(Operations)g(as)h(Propositional)e(Logic)i(F)o(ormulas)i
(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(95)459
2914 y(3.8.3)61 b(Implementing)11 b(Intersect)h(and)g(Except)h(Using)f
(the)h(Union)f(Capabilities)k(.)26 b(.)44 b(95)619 2974
y(P)o(arser)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g
(.)h(.)44 b(98)619 3034 y(T)n(ransformations)h(.)26 b(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)
h(.)f(.)g(.)h(.)19 b(105)619 3093 y(The)13 b(Re)o(write)f(System)42
b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)19 b(106)p eop
%%Page: 7 7
7 6 bop 198 633 a Fq(List)32 b(of)f(Figur)n(es)273 892
y Ft(1.1)52 b(The)13 b(suppliers)g(and)f(parts)g(database)36
b(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)
h(.)f(.)h(.)f(.)g(.)h(.)44 b(10)273 1001 y(3.1)52 b(Ho)o(w)12
b(a)h(connection)f(is)h(established)42 b(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(52)273 1061 y(3.2)52 b Fp(T)-5 b(ar)n(getList)12 b
Ft(and)h Fp(F)m(r)n(omList)g Ft(for)e(query)h(of)g(e)o(xample)h(3.1)35
b(.)25 b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(54)273 1121 y(3.3)52 b Fp(Wher)n(eClause)14 b Ft(for)e(query)g(of)g
(e)o(xample)g(3.1)23 b(.)i(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(55)273 1181 y(3.4)52
b(T)n(ransformed)12 b Fp(T)-5 b(ar)n(getList)12 b Ft(and)h
Fp(F)m(r)n(omList)g Ft(for)e(query)h(of)g(e)o(xample)h(3.1)28
b(.)e(.)f(.)h(.)f(.)g(.)h(.)44 b(56)273 1240 y(3.5)52
b(T)n(ransformed)12 b Fp(wher)n(e)i(clause)e Ft(for)g(query)g(of)g(e)o
(xample)g(3.1)23 b(.)j(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44
b(57)273 1300 y(3.6)52 b Fp(Plan)13 b Ft(for)e(query)h(of)g(e)o(xample)
h(3.1)45 b(.)26 b(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(61)273 1360
y(3.7)52 b Fp(Querytr)n(ee)14 b Ft(b)o(uilt)e(up)g(for)f(the)i(query)f
(of)g(e)o(xample)g(3.2)38 b(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f
(.)h(.)f(.)g(.)h(.)44 b(63)273 1420 y(3.8)52 b Fp(Plantr)n(ee)13
b Ft(for)f(the)g(query)g(of)g(e)o(xample)h(3.2)46 b(.)25
b(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g
(.)h(.)44 b(64)273 1479 y(3.9)52 b(Data)13 b(structure)f(handed)g(back)
g(by)h(the)f Fp(parser)49 b Ft(.)25 b(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)44 b(92)273 1539 y(3.10)27
b Fp(Plan)13 b Ft(for)e(a)i(union)f(query)44 b(.)25 b(.)h(.)f(.)g(.)h
(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)
f(.)h(.)f(.)g(.)h(.)44 b(93)273 1599 y(3.11)27 b Fp(Oper)o(ator)13
b(tr)n(ee)g Ft(for)f Fl(\()p Fk(A)g Fo([)f Fk(B)r Fl(\))p
Fo(n)p Fl(\()p Fk(C)k Fo(\\)d Fk(D)q Fl(\))29 b Ft(.)d(.)f(.)h(.)f(.)g
(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)19
b(101)273 1659 y(3.12)27 b(Data)13 b(structure)f(handed)g(back)g(by)h
Fr(SelectStmt)e Ft(rule)48 b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f
(.)g(.)h(.)19 b(102)273 1719 y(3.13)27 b(Data)13 b(structure)f(of)f
Fl(\()p Fk(A)h Fo([)g Fk(B)r Fl(\))p Fo(n)p Fk(C)k Ft(after)11
b(transformation)g(to)h(DNF)50 b(.)25 b(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)
19 b(107)273 1778 y(3.14)27 b(Data)13 b(structure)f(of)f
Fk(A)h Fo(\\)f Fk(C)16 b Ft(after)c(query)f(re)o(writing)40
b(.)26 b(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)g(.)h(.)f(.)h(.)f(.)g(.)h(.)19
b(109)1086 3552 y(7)p eop
%%Page: 8 8
8 7 bop eop
%%Page: 9 9
9 8 bop 198 661 a Fj(Chapter)26 b(1)198 964 y Fq(SQL)198
1276 y Ft(SQL)10 b(has)h(become)f(one)g(of)g(the)g(most)g(popular)f
(relational)g(query)h(languages)g(all)g(o)o(v)o(er)h(the)f(world.)k
(The)198 1336 y(name)i(\224SQL\224)g(is)g(an)g(abbre)o(viation)f(for)g
Fp(Structur)n(ed)h(Query)g(Language)p Ft(.)25 b(In)15
b(1974)h(Donald)f(Cham-)198 1395 y(berlin)f(and)g(others)g(de\002ned)h
(the)f(language)g(SEQUEL)h Fp(\(Structur)n(ed)g(English)g(Query)g
(Language\))d Ft(at)198 1455 y(IBM)f(Research.)16 b(This)11
b(language)f(was)h(\002rst)f(implemented)f(in)i(an)f(IBM)h(prototype)e
(called)i(SEQUEL-)198 1515 y(XRM)h(in)e(1974-75.)15 b(In)10
b(1976-77)g(a)i(re)o(vised)e(v)o(ersion)h(of)g(SEQUEL)g(called)g
(SEQUEL/2)g(was)g(de\002ned)198 1575 y(and)h(the)h(name)f(was)g
(changed)h(to)f(SQL)h(subsequently)m(.)273 1688 y(A)j(ne)o(w)f
(prototype)g(called)h(System)g(R)g(was)g(de)o(v)o(eloped)g(by)f(IBM)h
(in)g(1977.)26 b(System)16 b(R)g(imple-)198 1748 y(mented)f(a)h(lar)o
(ge)f(subset)h(of)f(SEQUEL/2)h(\(no)o(w)f(SQL\))g(and)h(a)f(number)g
(of)g(changes)h(were)g(made)f(to)198 1808 y(SQL)i(during)e(the)h
(project.)28 b(System)16 b(R)h(was)f(installed)g(in)h(a)f(number)g(of)g
(user)g(sites,)j(both)d(internal)198 1867 y(IBM)d(sites)h(and)f(also)g
(some)h(selected)f(customer)g(sites.)19 b(Thanks)13 b(to)g(the)g
(success)i(and)e(acceptance)h(of)198 1927 y(System)d(R)g(at)g(those)g
(user)h(sites)f(IBM)g(started)g(to)g(de)o(v)o(elop)g(commercial)f
(products)h(that)g(implemented)198 1987 y(the)h(SQL)h(language)f(based)
h(on)f(the)h(System)f(R)g(technology)m(.)273 2100 y(Ov)o(er)g(the)g(ne)
o(xt)g(years)h(IBM)f(and)h(also)f(a)h(number)e(of)h(other)g(v)o(endors)
g(announced)g(SQL)g(products)198 2160 y(such)18 b(as)h(SQL/DS)e
(\(IBM\),)h(DB2)g(\(IBM\))f(ORA)n(CLE)i(\(Oracle)e(Corp.\))32
b(DG/SQL)18 b(\(Data)f(General)198 2220 y(Corp.\))e(SYB)n(ASE)e
(\(Sybase)f(Inc.\).)273 2333 y(SQL)i(is)h(also)g(an)g(of)o(\002cial)e
(standard)h(no)o(w)m(.)22 b(In)14 b(1982)g(the)h(American)f(National)g
(Standards)g(Insti-)198 2392 y(tute)g(\(ANSI\))e(chartered)h(its)h
(Database)h(Committee)e(X3H2)g(to)h(de)o(v)o(elop)g(a)g(proposal)f(for)
g(a)h(standard)198 2452 y(relational)9 b(language.)16
b(This)10 b(proposal)g(was)h(rati\002ed)e(in)h(1986)g(and)g(consisted)h
(essentially)g(of)f(the)g(IBM)198 2512 y(dialect)j(of)f(SQL.)i(In)e
(1987)g(this)h(ANSI)f(standard)h(was)g(also)g(accepted)g(as)h(an)f
(international)e(standard)198 2572 y(by)h(the)g(International)f(Or)o
(ganization)g(for)g(Standardization)g(\(ISO\).)f(This)j(original)e
(standard)h(v)o(ersion)198 2632 y(of)k(SQL)g(is)h(often)f(referred)f
(to,)i(informally)m(,)f(as)h(\224SQL/86\224.)27 b(In)16
b(1989)g(the)h(original)e(standard)h(was)198 2691 y(e)o(xtended)c(and)f
(this)h(ne)o(w)f(standard)g(is)h(often,)g(again)f(informally)m(,)f
(referred)h(to)g(as)h(\224SQL/89\224.)k(Also)11 b(in)198
2751 y(1989,)i(a)f(related)g(standard)g(called)h Fp(Database)f
(Language)f(Embedded)i(SQL)f Ft(was)g(de)o(v)o(eloped.)273
2864 y(The)22 b(ISO)f(and)h(ANSI)f(committees)g(ha)o(v)o(e)i(been)f
(working)e(for)h(man)o(y)h(years)g(on)f(the)h(de\002ni-)198
2924 y(tion)g(of)g(a)h(greatly)f(e)o(xpanded)h(v)o(ersion)g(of)f(the)h
(original)e(standard,)26 b(referred)21 b(to)h(informally)g(as)198
2984 y(\224SQL2\224)17 b(or)f(\224SQL/92\224.)27 b(This)18
b(v)o(ersion)e(became)g(a)h(rati\002ed)f(standard)g(-)g
(\224International)f(Standard)198 3044 y(ISO/IEC)d(9075:1992)o(,)f
Fp(Database)f(Language)e(SQL)p Ft(\224)h(-)h(in)g(late)g(1992.)k
(\224SQL/92\224)c(is)g(the)g(v)o(ersion)g(nor)o(-)198
3103 y(mally)h(meant)g(when)g(people)h(refer)e(to)h(\224the)h(SQL)f
(standard\224.)16 b(A)11 b(detailed)g(description)g(of)g
(\224SQL/92\224)198 3163 y(is)18 b(gi)o(v)o(en)f(in)h([D)n(A)-6
b(TE96)q(].)31 b(At)18 b(the)f(time)h(of)f(writing)g(this)g(document)h
(a)g(ne)o(w)f(standard)h(informally)198 3223 y(referred)11
b(to)i(as)g(\224SQL3\224)g(is)g(under)f(de)o(v)o(elopment.)17
b(It)12 b(is)h(planned)f(to)h(make)f(SQL)h(a)g(turing-complete)198
3283 y(language,)e(i.e.)h(all)f(computable)f(queries)g(\(e.g.)16
b(recursi)o(v)o(e)10 b(queries\))g(will)h(be)f(possible.)16
b(This)11 b(is)g(a)g(v)o(ery)198 3342 y(comple)o(x)h(task)h(and)g
(therefore)e(the)h(completion)g(of)g(the)h(ne)o(w)f(standard)g(can)h
(not)f(be)h(e)o(xpected)g(before)198 3402 y(1999.)1086
3552 y(9)p eop
%%Page: 10 10
10 9 bop 270 60 a Ft(10)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)270 234 y Fi(1.1)71 b(The)18 b(Relational)f(Data)g(Model)270
346 y Ft(As)10 b(mentioned)f(before,)h(SQL)g(is)g(a)g(relational)e
(language.)15 b(That)10 b(means)g(it)g(is)g(based)g(on)f(the)h
(\224relational)270 405 y(data)j(model\224)f(\002rst)g(published)h(by)f
(E.F)l(.)i(Codd)e(in)h(1970.)j(W)l(e)d(will)f(gi)o(v)o(e)h(a)f(formal)g
(description)g(of)g(the)270 465 y(relational)h(model)h(in)f(section)h
(1.1.1)h Fp(F)-5 b(ormal)14 b(Notion)g(of)g(the)f(Relational)h(Data)g
(Model)g Ft(b)o(ut)f(\002rst)h(we)270 525 y(want)e(to)g(ha)o(v)o(e)h(a)
f(look)g(at)h(it)f(from)f(a)i(more)f(intuiti)o(v)o(e)f(point)h(of)g
(vie)o(w)m(.)345 585 y(A)19 b Fp(r)n(elational)g(database)g
Ft(is)h(a)f(database)h(that)f(is)h(percei)o(v)o(ed)f(by)g(its)g(users)h
(as)g(a)f Fp(collection)g(of)270 645 y(tables)13 b Ft(\(and)f(nothing)g
(else)i(b)o(ut)e(tables\).)17 b(A)c(table)g(consists)h(of)e(ro)o(ws)h
(and)f(columns)h(where)g(each)g(ro)o(w)270 704 y(represents)g(a)g
(record)f(and)h(each)g(column)f(represents)h(an)g(attrib)o(ute)f(of)g
(the)h(records)f(contained)h(in)f(the)270 764 y(table.)k(Figure)11
b(1.1)i(sho)o(ws)g(an)f(e)o(xample)h(of)f(a)g(database)h(consisting)g
(of)f(three)g(tables:)345 864 y Fo(\017)25 b Ft(SUPPLIER)16
b(is)h(a)f(table)h(storing)e(the)i(number)f(\(SNO\),)f(the)i(name)f
(\(SN)n(AME\))g(and)h(the)f(city)395 924 y(\(CITY\))11
b(of)h(a)h(supplier)m(.)345 1024 y Fo(\017)25 b Ft(P)-5
b(AR)m(T)10 b(is)g(a)g(table)g(storing)f(the)h(number)f(\(PNO\))g(the)g
(name)h(\(PN)n(AME\))g(and)f(the)h(price)g(\(PRICE\))395
1084 y(of)h(a)i(part.)345 1184 y Fo(\017)25 b Ft(SELLS)12
b(stores)g(information)e(about)h(which)h(part)f(\(PNO\))g(is)h(sold)f
(by)h(which)f(supplier)h(\(SNO\).)395 1243 y(It)f(serv)o(es)j(in)e(a)g
(sense)i(to)e(connect)g(the)h(other)e(two)h(tables)h(together)m(.)360
1391 y Fr(SUPPLIER)88 b(SNO)30 b(|)60 b(SNAME)f(|)h(CITY)178
b(SELLS)90 b(SNO)29 b(|)h(PNO)659 1451 y(-----+---------+--------)326
b(-----+-----)718 1511 y(1)60 b(|)g(Smith)f(|)30 b(London)417
b(1)60 b(|)g(1)718 1571 y(2)g(|)g(Jones)f(|)30 b(Paris)447
b(1)60 b(|)g(2)718 1631 y(3)g(|)g(Adams)f(|)30 b(Vienna)417
b(2)60 b(|)g(4)718 1690 y(4)g(|)g(Blake)f(|)30 b(Rome)477
b(3)60 b(|)g(1)1764 1750 y(3)g(|)g(3)1764 1810 y(4)g(|)g(2)360
1870 y(PART)208 b(PNO)30 b(|)60 b(PNAME)f(|)h(PRICE)417
b(4)60 b(|)g(3)659 1929 y(-----+---------+---------)355
b(4)60 b(|)g(4)718 1989 y(1)g(|)g(Screw)f(|)89 b(10)718
2049 y(2)60 b(|)g(Nut)119 b(|)g(8)718 2109 y(3)60 b(|)g(Bolt)89
b(|)g(15)718 2169 y(4)60 b(|)g(Cam)119 b(|)89 b(25)729
2328 y Ft(Figure)12 b(1.1:)j(The)e(suppliers)g(and)f(parts)g(database)
270 2448 y(The)h(tables)f(P)-5 b(AR)m(T)13 b(and)f(SUPPLIER)f(may)h(be)
g(re)o(garded)g(as)g Fp(entities)g Ft(and)g(SELLS)h(may)f(be)g(re)o
(garded)270 2507 y(as)h(a)g Fp(r)n(elationship)f Ft(between)g(a)h
(particular)e(part)h(and)h(a)f(particular)f(supplier)m(.)345
2567 y(As)k(we)g(will)f(see)h(later)n(,)g(SQL)g(operates)g(on)f(tables)
h(like)f(the)h(ones)g(just)g(de\002ned)f(b)o(ut)g(before)g(that)270
2627 y(we)f(will)e(study)i(the)f(theory)g(of)g(the)g(relational)g
(model.)270 2770 y Fh(1.1.1)59 b(F)o(ormal)13 b(Notion)i(of)f(the)h
(Relational)e(Data)i(Model)270 2864 y Ft(The)22 b(mathematical)f
(concept)g(underlying)f(the)h(relational)g(model)g(is)g(the)h
(set-theoretic)e Fp(r)n(elation)270 2924 y Ft(which)d(is)h(a)g(subset)g
(of)g(the)f(Cartesian)h(product)f(of)g(a)h(list)f(of)g(domains.)32
b(This)18 b(set-theoretic)f Fp(r)n(ela-)270 2983 y(tion)i
Ft(gi)o(v)o(es)g(the)g(model)g(its)g(name)g(\(do)g(not)g(confuse)g(it)g
(with)g(the)g(relationship)f(from)g(the)h Fp(Entity-)270
3043 y(Relationship)14 b(model)p Ft(\).)20 b(F)o(ormally)13
b(a)h(domain)g(is)g(simply)g(a)g(set)g(of)g(v)o(alues.)21
b(F)o(or)13 b(e)o(xample)h(the)g(set)h(of)270 3103 y(inte)o(gers)d(is)g
(a)g(domain.)j(Also)c(the)h(set)g(of)f(character)h(strings)f(of)g
(length)h(20)f(and)h(the)f(real)h(numbers)f(are)270 3163
y(e)o(xamples)i(of)f(domains.)270 3283 y Fn(De\002nition)f(1.1)25
b Ft(The)65 b Fp(Cartesian)g Ft(product)e(of)h(domains)h
Fk(D)1580 3290 y Fg(1)1602 3283 y Fk(;)8 b(D)1665 3290
y Fg(2)1688 3283 y Fk(;)g(:)g(:)g(:)h(;)f(D)1840 3290
y Ff(k)1929 3283 y Ft(written)270 3342 y Fk(D)311 3349
y Fg(1)345 3342 y Fo(\002)i Fk(D)435 3349 y Fg(2)469
3342 y Fo(\002)h Fk(:)d(:)g(:)j Fo(\002)g Fk(D)679 3349
y Ff(k)757 3342 y Ft(is)54 b(the)g(set)g(of)f(all)h Fk(k)r
Ft(-tuples)e Fl(\()p Fk(v)1526 3349 y Fg(1)1549 3342
y Fk(;)8 b(v)1595 3349 y Fg(2)1618 3342 y Fk(;)g(:)g(:)g(:)g(;)g(v)1752
3349 y Ff(k)1777 3342 y Fl(\))54 b Ft(such)g(that)270
3402 y Fk(v)294 3409 y Fg(1)330 3402 y Fo(2)14 b Fk(D)418
3409 y Fg(1)441 3402 y Fk(;)8 b(v)487 3409 y Fg(2)523
3402 y Fo(2)14 b Fk(D)611 3409 y Fg(2)634 3402 y Fk(;)8
b(:)g(:)g(:)h(;)f(v)769 3409 y Ff(k)807 3402 y Fo(2)14
b Fk(D)895 3409 y Ff(k)920 3402 y Ft(.)p eop
%%Page: 11 11
11 10 bop 198 60 a Fm(1.2.)29 b(OPERA)-6 b(TIONS)12 b(IN)g(THE)i(RELA)
-6 b(TION)n(AL)14 b(D)n(A)-6 b(T)h(A)14 b(MODEL)521 b
Ft(11)198 234 y(F)o(or)16 b(e)o(xample,)h(when)f(we)g(ha)o(v)o(e)g
Fk(k)22 b Fl(=)f(2)p Ft(,)c Fk(D)989 241 y Fg(1)1032
234 y Fl(=)j Fo(f)p Fl(0)p Fk(;)8 b Fl(1)p Fo(g)16 b
Ft(and)g Fk(D)1358 241 y Fg(2)1401 234 y Fl(=)21 b Fo(f)p
Fk(a;)8 b(b;)g(c)p Fo(g)p Ft(,)17 b(then)f Fk(D)1796
241 y Fg(1)1833 234 y Fo(\002)d Fk(D)1926 241 y Fg(2)1965
234 y Ft(is)198 294 y Fo(f)p Fl(\(0)p Fk(;)8 b(a)p Fl(\))p
Fk(;)g Fl(\(0)p Fk(;)g(b)p Fl(\))p Fk(;)g Fl(\(0)p Fk(;)g(c)p
Fl(\))p Fk(;)g Fl(\(1)p Fk(;)g(a)q Fl(\))p Fk(;)g Fl(\()q(1)p
Fk(;)g(b)p Fl(\))p Fk(;)h Fl(\(1)p Fk(;)f(c)p Fl(\))p
Fo(g)p Ft(.)198 420 y Fn(De\002nition)j(1.2)25 b Ft(A)13
b(Relation)g(is)h(an)o(y)g(subset)f(of)g(the)h(Cartesian)f(product)g
(of)f(one)i(or)f(more)f(domains:)198 480 y Fk(R)i Fo(\022)e
Fk(D)342 487 y Fg(1)376 480 y Fo(\002)f Fk(D)467 487
y Fg(2)500 480 y Fo(\002)g Fk(:)d(:)g(:)j Fo(\002)g Fk(D)710
487 y Ff(k)198 584 y Ft(F)o(or)g(e)o(xample)h Fo(f)p
Fl(\(0)p Fk(;)c(a)p Fl(\))p Fk(;)g Fl(\(0)p Fk(;)g(b)p
Fl(\))p Fk(;)g Fl(\(1)p Fk(;)g(a)p Fl(\))p Fo(g)15 b
Ft(is)d(a)g(relation,)f(it)g(is)h(in)g(fact)f(a)g(subset)i(of)e
Fk(D)1635 591 y Fg(1)1666 584 y Fo(\002)d Fk(D)1754 591
y Fg(2)1788 584 y Ft(mentioned)198 644 y(abo)o(v)o(e.)15
b(The)10 b(members)g(of)f(a)h(relation)e(are)i(called)f(tuples.)15
b(Each)10 b(relation)f(of)g(some)h(Cartesian)g(product)198
703 y Fk(D)239 710 y Fg(1)273 703 y Fo(\002)g Fk(D)363
710 y Fg(2)397 703 y Fo(\002)h Fk(:)d(:)g(:)j Fo(\002)g
Fk(D)607 710 y Ff(k)644 703 y Ft(is)i(said)g(to)f(ha)o(v)o(e)g(arity)g
Fk(k)i Ft(and)f(is)f(therefore)f(a)i(set)g(of)f Fk(k)r
Ft(-tuples.)273 764 y(A)j(relation)f(can)h(be)f(vie)o(wed)h(as)g(a)g
(table)g(\(as)g(we)g(already)f(did,)i(remember)d(\002gure)i(1.1)g
Fp(The)f(sup-)198 824 y(pliers)j(and)g(parts)h(database)p
Ft(\))f(where)g(e)o(v)o(ery)g(tuple)g(is)g(represented)g(by)g(a)h(ro)o
(w)e(and)i(e)o(v)o(ery)f(column)198 884 y(corresponds)c(to)h(one)f
(component)g(of)g(a)h(tuple.)19 b(Gi)o(ving)13 b(names)h(\(called)f
(attrib)o(utes\))f(to)i(the)f(columns)198 944 y(leads)g(to)f(the)g
(de\002nition)g(of)g(a)g Fp(r)n(elation)h(sc)o(heme)p
Ft(.)198 1070 y Fn(De\002nition)e(1.3)25 b Ft(A)12 b
Fp(r)n(elation)g(sc)o(heme)h Fk(R)g Ft(is)f(a)g(\002nite)g(set)g(of)g
(attrib)o(utes)g Fo(f)p Fk(A)1507 1077 y Fg(1)1529 1070
y Fk(;)c(A)1588 1077 y Fg(2)1611 1070 y Fk(;)g(:)g(:)g(:)h(;)f(A)1759
1077 y Ff(k)1784 1070 y Fo(g)p Ft(.)15 b(There)e(is)198
1130 y(a)h(domain)g Fk(D)439 1137 y Ff(i)470 1130 y Ft(for)g(each)g
(attrib)o(ute)g Fk(A)865 1137 y Ff(i)882 1130 y Fk(;)8
b Fl(1)17 b Fo(\024)g Fk(i)g Fo(\024)g Fk(k)f Ft(where)e(the)g(v)o
(alues)h(of)f(the)g(attrib)o(utes)f(are)i(taken)198 1189
y(from.)g(W)l(e)d(often)g(write)g(a)h(relation)e(scheme)i(as)g
Fk(R)p Fl(\()p Fk(A)1139 1196 y Fg(1)1162 1189 y Fk(;)8
b(A)1221 1196 y Fg(2)1244 1189 y Fk(;)g(:)g(:)g(:)h(;)f(A)1392
1196 y Ff(k)1417 1189 y Fl(\))p Ft(.)198 1293 y Fn(Note:)21
b Ft(A)15 b Fp(r)n(elation)g(sc)o(heme)i Ft(is)e(just)h(a)f(kind)g(of)g
(template)g(whereas)h(a)g Fp(r)n(elation)f Ft(is)h(an)f(instance)h(of)f
(a)198 1353 y Fp(r)n(elation)h(sc)o(heme)p Ft(.)26 b(The)17
b Fp(r)n(elation)e Ft(consists)i(of)e(tuples)h(\(and)f(can)h(therefore)
e(be)i(vie)o(wed)f(as)i(a)f(table\))198 1413 y(not)c(so)h(the)f
Fp(r)n(elation)h(sc)o(heme)p Ft(.)198 1552 y Fn(Domains)g(vs.)j(Data)c
(T)l(ypes)198 1647 y Ft(W)l(e)j(often)g(talked)f(about)h
Fp(domains)g Ft(in)g(the)g(last)g(section.)25 b(Recall)15
b(that)g(a)g(domain)g(is,)h(formally)m(,)f(just)198 1707
y(a)f(set)g(of)f(v)o(alues)h(\(e.g.,)h(the)e(set)h(of)g(inte)o(gers)f
(or)g(the)h(real)f(numbers\).)19 b(In)13 b(terms)h(of)f(database)h
(systems)198 1767 y(we)f(often)f(talk)g(of)g Fp(data)h(types)g
Ft(instead)g(of)f(domains.)k(When)d(we)g(de\002ne)f(a)h(table)g(we)f
(ha)o(v)o(e)h(to)g(make)f(a)198 1827 y(decision)j(about)f(which)g
(attrib)o(utes)g(to)g(include.)22 b(Additionally)14 b(we)g(ha)o(v)o(e)h
(to)g(decide)f(which)g(kind)h(of)198 1886 y(data)f(is)f(going)g(to)h
(be)f(stored)h(as)g(attrib)o(ute)e(v)o(alues.)20 b(F)o(or)13
b(e)o(xample)g(the)h(v)o(alues)f(of)h(SN)n(AME)g(from)e(the)198
1946 y(table)g(SUPPLIER)f(will)g(be)h(character)f(strings,)h(whereas)g
(SNO)f(will)h(store)f(inte)o(gers.)16 b(W)l(e)c(de\002ne)f(this)198
2006 y(by)f(assigning)f(a)h Fp(data)g(type)f Ft(to)h(each)g(attrib)o
(ute.)k(The)c(type)f(of)h(SN)n(AME)g(will)f(be)h(V)-7
b(ARCHAR\(20\))9 b(\(this)198 2066 y(is)14 b(the)f(SQL)h(type)f(for)g
(character)g(strings)g(of)h(length)f Fo(\024)g Ft(20\),)h(the)f(type)h
(of)f(SNO)g(will)g(be)g(INTEGER.)198 2125 y(W)n(ith)i(the)h(assignment)
g(of)f(a)g Fp(data)h(type)f Ft(we)h(also)g(ha)o(v)o(e)g(selected)g(a)g
(domain)f(for)f(an)i(attrib)o(ute.)25 b(The)198 2185
y(domain)12 b(of)g(SN)n(AME)i(is)f(the)f(set)h(of)f(all)h(character)f
(strings)h(of)f(length)g Fo(\024)h Ft(20,)g(the)f(domain)g(of)g(SNO)h
(is)198 2245 y(the)f(set)h(of)f(all)g(inte)o(ger)g(numbers.)198
2419 y Fi(1.2)71 b(Operations)17 b(in)h(the)f(Relational)g(Data)g
(Model)198 2533 y Ft(In)11 b(section)h(1.1.1)g(we)g(de\002ned)f(the)g
(mathematical)g(notion)g(of)g(the)h(relational)f(model.)k(No)o(w)c(we)h
(kno)o(w)198 2592 y(ho)o(w)j(the)g(data)h(can)g(be)f(stored)g(using)h
(a)f(relational)g(data)g(model)g(b)o(ut)h(we)f(do)h(not)f(kno)o(w)g
(what)g(to)g(do)198 2652 y(with)g(all)f(these)i(tables)f(to)g(retrie)o
(v)o(e)f(something)g(from)g(the)h(database)g(yet.)24
b(F)o(or)14 b(e)o(xample)h(somebody)198 2712 y(could)i(ask)g(for)f(the)
h(names)g(of)g(all)g(suppliers)g(that)g(sell)g(the)g(part)f('Scre)o
(w'.)28 b(Therefore)17 b(two)f(rather)198 2772 y(dif)o(ferent)11
b(kinds)h(of)g(notations)g(for)g(e)o(xpressing)g(operations)g(on)h
(relations)f(ha)o(v)o(e)g(been)h(de\002ned:)273 2875
y Fo(\017)25 b Ft(The)14 b Fp(Relational)f(Algebr)o(a)g
Ft(which)h(is)f(an)h(algebraic)f(notation,)g(where)h(queries)f(are)g(e)
o(xpressed)323 2934 y(by)f(applying)g(specialized)g(operators)g(to)g
(the)h(relations.)273 3039 y Fo(\017)25 b Ft(The)13 b
Fp(Relational)f(Calculus)h Ft(which)f(is)h(a)g(logical)g(notation,)f
(where)h(queries)f(are)h(e)o(xpressed)g(by)323 3098 y(formulating)d
(some)j(logical)f(restrictions)g(that)g(the)g(tuples)h(in)f(the)g
(answer)h(must)f(satisfy)m(.)198 3247 y Fh(1.2.1)59 b(Relational)14
b(Algebra)198 3342 y Ft(The)20 b Fp(Relational)f(Algebr)o(a)h
Ft(was)f(introduced)g(by)g(E.)i(F)l(.)e(Codd)h(in)f(1972.)37
b(It)19 b(consists)h(of)f(a)h(set)g(of)198 3402 y(operations)12
b(on)g(relations:)p eop
%%Page: 12 12
12 11 bop 270 60 a Ft(12)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)345 234 y Fo(\017)d Ft(SELECT)17 b(\()p Fk(\033)r
Ft(\):)j(e)o(xtracts)c Fp(tuples)g Ft(from)e(a)i(relation)e(that)i
(satisfy)f(a)h(gi)o(v)o(en)f(restriction.)24 b(Let)16
b Fk(R)395 294 y Ft(be)f(a)h(table)g(that)f(contains)h(an)g(attrib)o
(ute)e Fk(A)p Ft(.)27 b Fk(\033)1227 301 y Ff(A)p Fg(=)p
Ff(a)1312 294 y Fl(\()p Fk(R)p Fl(\))21 b(=)e Fo(f)p
Fk(t)h Fo(2)g Fk(R)g Fo(j)g Fk(t)p Fl(\()p Fk(A)p Fl(\))h(=)f
Fk(a)p Fo(g)c Ft(where)f Fk(t)395 354 y Ft(denotes)d(a)h(tuple)f(of)g
Fk(R)g Ft(and)h Fk(t)p Fl(\()p Fk(A)p Fl(\))g Ft(denotes)g(the)f(v)o
(alue)g(of)g(attrib)o(ute)g Fk(A)h Ft(of)f(tuple)g Fk(t)p
Ft(.)345 471 y Fo(\017)25 b Ft(PR)n(OJECT)17 b(\()p Fk(\031)r
Ft(\):)22 b(e)o(xtracts)16 b(speci\002ed)g Fp(attrib)o(utes)g
Ft(\(columns\))f(from)g(a)h(relation.)26 b(Let)17 b Fk(R)f
Ft(be)g(a)395 530 y(relation)10 b(that)h(contains)g(an)g(attrib)o(ute)f
Fk(X)t Ft(.)16 b Fk(\031)1156 537 y Ff(X)1194 530 y Fl(\()p
Fk(R)p Fl(\))f(=)f Fo(f)p Fk(t)p Fl(\()p Fk(X)t Fl(\))g
Fo(j)g Fk(t)g Fo(2)g Fk(R)p Fo(g)p Ft(,)e(where)f Fk(t)p
Fl(\()p Fk(X)t Fl(\))h Ft(denotes)395 590 y(the)g(v)o(alue)g(of)g
(attrib)o(ute)f Fk(X)17 b Ft(of)12 b(tuple)g Fk(t)p Ft(.)345
707 y Fo(\017)25 b Ft(PR)n(ODUCT)12 b(\()p Fo(\002)p
Ft(\):)i(b)o(uilds)f(the)f(Cartesian)g(product)g(of)f(two)h(relations.)
j(Let)e Fk(R)g Ft(be)f(a)g(table)g(with)395 767 y(arity)i
Fk(k)527 774 y Fg(1)564 767 y Ft(and)h(let)g Fk(S)i Ft(be)e(a)g(table)g
(with)f(arity)g Fk(k)1210 774 y Fg(2)1233 767 y Ft(.)23
b Fk(R)13 b Fo(\002)g Fk(S)k Ft(is)e(the)g(set)g(of)g(all)g
Fl(\()p Fk(k)1780 774 y Fg(1)1815 767 y Fl(+)e Fk(k)1893
774 y Fg(2)1915 767 y Fl(\))p Ft(-tuples)395 827 y(whose)h(\002rst)f
Fk(k)653 834 y Fg(1)690 827 y Ft(components)g(form)g(a)h(tuple)g(in)g
Fk(R)g Ft(and)g(whose)g(last)g Fk(k)1646 834 y Fg(2)1682
827 y Ft(components)g(form)f(a)395 887 y(tuple)f(in)g
Fk(S)s Ft(.)345 1004 y Fo(\017)25 b Ft(UNION)13 b(\()p
Fo([)p Ft(\):)18 b(b)o(uilds)c(the)g(set-theoretic)f(union)h(of)g(two)f
(tables.)21 b(Gi)o(v)o(en)14 b(the)g(tables)g Fk(R)h
Ft(and)f Fk(S)395 1063 y Ft(\(both)e(must)g(ha)o(v)o(e)h(the)g(same)g
(arity\),)g(the)f(union)h Fk(R)e Fo([)h Fk(S)j Ft(is)e(the)g(set)g(of)g
(tuples)g(that)f(are)h(in)f Fk(R)i Ft(or)395 1123 y Fk(S)g
Ft(or)e(both.)345 1240 y Fo(\017)25 b Ft(INTERSECT)12
b(\()p Fo(\\)p Ft(\):)h(b)o(uilds)e(the)f(set-theoretic)g(intersection)
g(of)g(two)g(tables.)16 b(Gi)o(v)o(en)10 b(the)h(tables)395
1300 y Fk(R)j Ft(and)f Fk(S)s Ft(,)i Fk(R)d Fo([)g Fk(S)17
b Ft(is)d(the)g(set)g(of)f(tuples)h(that)g(are)g(in)f
Fk(R)h Ft(and)g(in)g Fk(S)s Ft(.)20 b(W)l(e)14 b(again)f(require)g
(that)h Fk(R)395 1360 y Ft(and)e Fk(S)j Ft(ha)o(v)o(e)e(the)f(same)h
(arity)m(.)345 1477 y Fo(\017)25 b Ft(DIFFERENCE)14 b(\()p
Fo(\000)g Ft(or)f Fo(n)p Ft(\):)18 b(b)o(uilds)c(the)g(set)h(dif)o
(ference)d(of)i(two)f(tables.)21 b(Let)15 b Fk(R)f Ft(and)g
Fk(S)i Ft(again)395 1536 y(be)c(two)g(tables)g(with)g(the)h(same)g
(arity)m(.)h Fk(R)e Fo(\000)f Fk(S)j Ft(is)f(the)f(set)h(of)f(tuples)h
(in)f Fk(R)h Ft(b)o(ut)f(not)g(in)g Fk(S)s Ft(.)345 1653
y Fo(\017)25 b Ft(JOIN)d(\()p Fe(1)p Ft(\):)36 b(connects)23
b(two)g(tables)g(by)g(their)f(common)g(attrib)o(utes.)47
b(Let)24 b Fk(R)f Ft(be)g(a)g(table)395 1713 y(with)18
b(the)g(attrib)o(utes)g Fk(A;)8 b(B)22 b Ft(and)c Fk(C)k
Ft(and)c(let)h Fk(S)i Ft(a)e(table)f(with)g(the)h(attrib)o(utes)f
Fk(C)q(;)8 b(D)19 b Ft(and)g Fk(E)s Ft(.)395 1773 y(There)k(is)g(one)g
(attrib)o(ute)f(common)g(to)h(both)f(relations,)k(the)d(attrib)o(ute)f
Fk(C)t Ft(.)47 b Fk(R)33 b Fe(1)g Fk(S)j Fl(=)395 1833
y Fk(\031)423 1840 y Ff(R:A;R:B)r(;R:C;S:D)q(;S:E)826
1833 y Fl(\()p Fk(\033)873 1840 y Ff(R:C)r Fg(=)p Ff(S:C)1047
1833 y Fl(\()p Fk(R)15 b Fo(\002)e Fk(S)s Fl(\)\))p Ft(.)27
b(What)16 b(are)g(we)g(doing)f(here?)27 b(W)l(e)16 b(\002rst)f(cal-)395
1893 y(culate)g(the)h(Cartesian)f(product)g Fk(R)f Fo(\002)f
Fk(S)s Ft(.)24 b(Then)16 b(we)g(select)g(those)g(tuples)f(whose)h(v)o
(alues)g(for)395 1952 y(the)c(common)g(attrib)o(ute)g
Fk(C)k Ft(are)d(equal)f(\()p Fk(\033)1124 1959 y Ff(R:C)r
Fg(=)p Ff(S:C)1297 1952 y Ft(\).)17 b(No)o(w)12 b(we)h(got)f(a)h(table)
g(that)f(contains)h(the)395 2012 y(attrib)o(ute)e Fk(C)16
b Ft(two)11 b(times)i(and)f(we)h(correct)e(this)i(by)f(projecting)f
(out)i(the)f(duplicate)g(column.)395 2153 y Fn(Example)g(1.1)25
b Ft(Let')m(s)11 b(ha)o(v)o(e)g(a)g(look)f(at)g(the)g(tables)h(that)f
(are)h(produced)e(by)i(e)o(v)o(aluating)e(the)h(steps)395
2213 y(necessary)j(for)e(a)i(join.)395 2273 y(Let)f(the)h(follo)o(wing)
e(two)g(tables)i(be)f(gi)o(v)o(en:)664 2410 y Fr(R)89
b(A)30 b(|)g(B)f(|)h(C)179 b(S)90 b(C)30 b(|)f(D)h(|)g(E)753
2470 y(---+---+---)238 b(---+---+---)783 2529 y(1)30
b(|)g(2)f(|)h(3)299 b(3)30 b(|)f(a)h(|)g(b)783 2589 y(4)g(|)g(5)f(|)h
(6)299 b(6)30 b(|)f(c)h(|)g(d)783 2649 y(7)g(|)g(8)f(|)h(9)395
2786 y Ft(First)11 b(we)i(calculate)f(the)h(Cartesian)f(product)g
Fk(R)f Fo(\002)g Fk(S)k Ft(and)d(get:)604 2923 y Fr(R)30
b(x)f(S)90 b(A)30 b(|)f(B)h(|)g(R.C)g(|)f(S.C)h(|)g(D)f(|)h(E)813
2983 y(---+---+-----+-----+---+---)843 3042 y(1)g(|)f(2)h(|)60
b(3)g(|)f(3)h(|)30 b(a)f(|)h(b)843 3102 y(1)g(|)f(2)h(|)60
b(3)g(|)f(6)h(|)30 b(c)f(|)h(d)843 3162 y(4)g(|)f(5)h(|)60
b(6)g(|)f(3)h(|)30 b(a)f(|)h(b)843 3222 y(4)g(|)f(5)h(|)60
b(6)g(|)f(6)h(|)30 b(c)f(|)h(d)843 3281 y(7)g(|)f(8)h(|)60
b(9)g(|)f(3)h(|)30 b(a)f(|)h(b)843 3341 y(7)g(|)f(8)h(|)60
b(9)g(|)f(6)h(|)30 b(c)f(|)h(d)p eop
%%Page: 13 13
13 12 bop 198 60 a Fm(1.2.)29 b(OPERA)-6 b(TIONS)12 b(IN)g(THE)i(RELA)
-6 b(TION)n(AL)14 b(D)n(A)-6 b(T)h(A)14 b(MODEL)521 b
Ft(13)323 234 y(After)11 b(the)h(selection)h Fk(\033)731
241 y Ff(R:C)r Fg(=)p Ff(S:C)905 234 y Fl(\()p Fk(R)e
Fo(\002)g Fk(S)s Fl(\))h Ft(we)h(get:)771 347 y Fr(A)30
b(|)f(B)h(|)g(R.C)g(|)f(S.C)h(|)g(D)f(|)h(E)741 407 y
(---+---+-----+-----+---+---)771 467 y(1)g(|)f(2)h(|)60
b(3)g(|)f(3)h(|)30 b(a)f(|)h(b)771 526 y(4)g(|)f(5)h(|)60
b(6)g(|)f(6)h(|)30 b(c)f(|)h(d)323 639 y Ft(T)l(o)16
b(remo)o(v)o(e)g(the)f(duplicate)h(column)f Fk(S:C)k
Ft(we)d(project)f(it)h(out)f(by)h(the)g(follo)o(wing)e(operation:)323
699 y Fk(\031)351 706 y Ff(R:A;R:B)r(;R:C;S:D)q(;S:E)754
699 y Fl(\()p Fk(\033)801 706 y Ff(R:C)r Fg(=)p Ff(S:C)975
699 y Fl(\()p Fk(R)e Fo(\002)f Fk(S)s Fl(\)\))h Ft(and)h(get:)890
812 y Fr(A)30 b(|)g(B)g(|)g(C)f(|)h(D)g(|)g(E)861 872
y(---+---+---+---+---)890 931 y(1)g(|)g(2)g(|)g(3)f(|)h(a)g(|)g(b)890
991 y(4)g(|)g(5)g(|)g(6)f(|)h(c)g(|)g(d)273 1104 y Fo(\017)25
b Ft(DIVIDE)11 b(\()p Fo(\004)p Ft(\):)k(Let)d Fk(R)g
Ft(be)g(a)g(table)g(with)f(the)h(attrib)o(utes)f Fk(A;)d(B)r(;)g(C)16
b Ft(and)c Fk(D)i Ft(and)d(let)h Fk(S)i Ft(be)e(a)g(table)323
1164 y(with)i(the)h(attrib)o(utes)f Fk(C)k Ft(and)d Fk(D)q
Ft(.)24 b(Then)16 b(we)f(de\002ne)g(the)f(di)o(vision)h(as:)21
b Fk(R)13 b Fo(\004)g Fk(S)21 b Fl(=)e Fo(f)p Fk(t)f
Fo(j)g(8)p Fk(t)1926 1171 y Ff(s)1965 1164 y Fo(2)323
1224 y Fk(S)c Fo(9)p Fk(t)414 1231 y Ff(r)450 1224 y
Fo(2)g Fk(R)e Ft(such)g(that)g Fk(t)755 1231 y Ff(r)777
1224 y Fl(\()p Fk(A;)c(B)r Fl(\))15 b(=)f Fk(t)21 b Fo(^)h
Fk(t)1094 1231 y Ff(r)1116 1224 y Fl(\()p Fk(C)q(;)8
b(D)q Fl(\))15 b(=)e Fk(t)1340 1231 y Ff(s)1362 1224
y Fo(g)f Ft(where)f Fk(t)1550 1231 y Ff(r)1572 1224 y
Fl(\()p Fk(x;)d(y)r Fl(\))14 b Ft(denotes)e(a)g(tuple)323
1283 y(of)i(table)g Fk(R)h Ft(that)g(consists)g(only)f(of)g(the)h
(components)f Fk(x)i Ft(and)e Fk(y)r Ft(.)23 b(Note)14
b(that)h(the)f(tuple)h Fk(t)f Ft(only)323 1343 y(consists)f(of)f(the)g
(components)g Fk(A)h Ft(and)f Fk(B)j Ft(of)d(relation)g
Fk(R)p Ft(.)323 1459 y Fn(Example)g(1.2)25 b Ft(Gi)o(v)o(en)13
b(the)f(follo)o(wing)f(tables)621 1571 y Fr(R)90 b(A)30
b(|)g(B)f(|)h(C)g(|)g(D)239 b(S)89 b(C)30 b(|)g(D)711
1631 y(---+---+---+---)297 b(---+---)741 1691 y(a)30
b(|)g(b)f(|)h(c)g(|)g(d)358 b(c)30 b(|)g(d)741 1751 y(a)g(|)g(b)f(|)h
(e)g(|)g(f)358 b(e)30 b(|)g(f)741 1811 y(b)g(|)g(c)f(|)h(e)g(|)g(f)741
1870 y(e)g(|)g(d)f(|)h(c)g(|)g(d)741 1930 y(e)g(|)g(d)f(|)h(e)g(|)g(f)
741 1990 y(a)g(|)g(b)f(|)h(d)g(|)g(e)323 2103 y Fk(R)11
b Fo(\004)h Fk(S)i Ft(is)f(deri)o(v)o(ed)f(as)1070 2216
y Fr(A)30 b(|)f(B)1040 2275 y(---+---)1070 2335 y(a)h(|)f(b)1070
2395 y(e)h(|)f(d)198 2508 y Ft(F)o(or)12 b(a)g(more)g(detailed)g
(description)g(and)g(de\002nition)g(of)g(the)g(relational)g(algebra)g
(refer)f(to)h([ULL88])h(or)198 2568 y([D)n(A)-6 b(TE94)q(].)198
2683 y Fn(Example)13 b(1.3)25 b Ft(Recall)12 b(that)g(we)h(formulated)e
(all)h(those)g(relational)g(operators)f(to)h(be)h(able)f(to)g(retrie)o
(v)o(e)198 2743 y(data)i(from)e(the)i(database.)20 b(Let')m(s)14
b(return)f(to)g(our)g(e)o(xample)h(of)f(section)h(1.2)g(where)f
(someone)h(wanted)198 2803 y(to)d(kno)o(w)f(the)h(names)g(of)g(all)g
(suppliers)f(that)h(sell)g(the)g(part)g('Scre)o(w'.)i(This)f(question)f
(can)g(be)g(answered)198 2862 y(using)h(relational)g(algebra)g(by)g
(the)h(follo)o(wing)e(operation:)222 2965 y Fk(\031)250
2972 y Ff(S)r(U)t(P)5 b(P)g(LI)s(E)r(R:S)r(N)t(AM)t(E)657
2965 y Fl(\()p Fk(\033)704 2972 y Ff(P)g(ART)s(:P)g(N)t(AM)t(E)r
Fg(=)1033 2963 y Fd(0)1047 2972 y Ff(S)r(cr)q(ew)1159
2963 y Fd(0)1176 2965 y Fl(\()p Fk(S)s(U)g(P)i(P)g(LI)t(E)s(R)13
b Fe(1)h Fk(S)s(E)s(LLS)h Fe(1)f Fk(P)7 b(ART)g Fl(\)\))198
3068 y Ft(W)l(e)14 b(call)g(such)g(an)g(operation)g(a)g(query)m(.)20
b(If)13 b(we)h(e)o(v)o(aluate)f(the)h(abo)o(v)o(e)h(query)e(against)h
(the)g(tables)g(form)198 3128 y(\002gure)e(1.1)g Fp(The)h(suppliers)f
(and)g(parts)h(database)g Ft(we)f(will)g(obtain)g(the)g(follo)o(wing)f
(result:)1065 3222 y Fr(SNAME)1035 3282 y(-------)1065
3342 y(Smith)1065 3402 y(Adams)p eop
%%Page: 14 14
14 13 bop 270 60 a Ft(14)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)270 234 y Fh(1.2.2)59 b(Relational)14 b(Calculus)270
332 y Ft(The)20 b(relational)f(calculus)g(is)h(based)g(on)f(the)g
(\002rst)g(order)g(logic.)37 b(There)19 b(are)h(two)e(v)o(ariants)h(of)
g(the)270 391 y(relational)12 b(calculus:)345 498 y Fo(\017)25
b Ft(The)13 b Fp(Domain)g(Relational)f(Calculus)i Ft(\(DRC\),)f(where)g
(v)o(ariables)f(stand)i(for)e(components)h(\(at-)395
557 y(trib)o(utes\))e(of)h(the)g(tuples.)345 666 y Fo(\017)25
b Ft(The)12 b Fp(T)m(uple)h(Relational)f(Calculus)g Ft(\(TRC\),)h
(where)f(v)o(ariables)g(stand)h(for)f(tuples.)270 772
y(W)l(e)j(want)g(to)g(discuss)h(the)f(tuple)g(relational)f(calculus)h
(only)g(because)h(it)f(is)g(the)g(one)g(underlying)f(the)270
832 y(most)c(relational)g(languages.)16 b(F)o(or)10 b(a)g(detailed)g
(discussion)h(on)g(DRC)g(\(and)f(also)h(TRC\))g(see)g([D)n(A)-6
b(TE94])270 891 y(or)12 b([ULL88].)270 1036 y Fn(T)-5
b(uple)12 b(Relational)g(Calculus)270 1133 y Ft(The)h(queries)f(used)h
(in)f(TRC)i(are)e(of)g(the)g(follo)o(wing)f(form:)1019
1247 y Fo(f)p Fk(x)p Fl(\()p Fk(A)p Fl(\))k Fo(j)f Fk(F)7
b Fl(\()p Fk(x)p Fl(\))p Fo(g)270 1361 y Ft(where)k Fk(x)h
Ft(is)g(a)f(tuple)g(v)o(ariable)g Fk(A)h Ft(is)g(a)f(set)h(of)f(attrib)
o(utes)g(and)g Fk(F)19 b Ft(is)11 b(a)h(formula.)i(The)e(resulting)f
(relation)270 1421 y(consists)i(of)f(all)g(tuples)h Fk(t)p
Fl(\()p Fk(A)p Fl(\))g Ft(that)g(satisfy)f Fk(F)7 b Fl(\()p
Fk(t)p Fl(\))p Ft(.)270 1554 y Fn(Example)13 b(1.4)25
b Ft(If)9 b(we)h(want)g(to)g(answer)g(the)g(question)g(from)f(e)o
(xample)h(1.3)g(using)g(TRC)h(we)f(formulate)270 1613
y(the)i(follo)o(wing)f(query:)370 1725 y Fo(f)p Fk(x)p
Fl(\()p Fk(S)s(N)5 b(AM)g(E)s Fl(\))51 b Fo(j)f Fk(x)14
b Fo(2)g Fk(S)s(U)5 b(P)i(P)g(LI)t(E)s(R)12 b Fo(^)785
1785 y(9)p Fk(y)k Fo(2)e Fk(S)s(E)s(LLS)g Fo(9)p Fk(z)h
Fo(2)f Fk(P)7 b(ART)58 b Fl(\()p Fk(y)r Fl(\()p Fk(S)s(N)5
b(O)q Fl(\))15 b(=)f Fk(x)p Fl(\()p Fk(S)s(N)5 b(O)q
Fl(\))14 b Fo(^)1413 1845 y Fk(z)r Fl(\()p Fk(P)7 b(N)e(O)q
Fl(\))16 b(=)d Fk(y)r Fl(\()p Fk(P)7 b(N)e(O)q Fl(\))15
b Fo(^)1413 1904 y Fk(z)r Fl(\()p Fk(P)7 b(N)e(AM)g(E)s
Fl(\))16 b(=)1745 1886 y Fc(0)1773 1904 y Fk(S)s(cr)q(ew)1912
1886 y Fc(0)1926 1904 y Fl(\))p Fo(g)270 2016 y Ft(Ev)o(aluating)f(the)
h(query)f(against)h(the)f(tables)h(from)e(\002gure)h(1.1)h
Fp(The)g(suppliers)g(and)f(parts)h(database)270 2075
y Ft(again)c(leads)h(to)f(the)g(same)h(result)f(as)h(in)g(e)o(xample)f
(1.3.)270 2230 y Fh(1.2.3)59 b(Relational)14 b(Algebra)f(vs.)19
b(Relational)13 b(Calculus)270 2327 y Ft(The)j(relational)g(algebra)f
(and)h(the)g(relational)f(calculus)i(ha)o(v)o(e)f(the)g(same)g
Fp(e)o(xpr)n(essive)i(power)e Ft(i.e.)h(all)270 2387
y(queries)g(that)f(can)i(be)e(formulated)g(using)h(relational)f
(algebra)h(can)g(also)g(be)g(formulated)e(using)i(the)270
2447 y(relational)9 b(calculus)h(and)g(vice)g(v)o(ersa.)16
b(This)10 b(was)g(\002rst)g(pro)o(v)o(ed)g(by)g(E.)h(F)l(.)f(Codd)g(in)
g(1972.)k(This)d(proof)e(is)270 2507 y(based)k(on)g(an)f(algorithm)g
(-\224Codd')m(s)g(reduction)g(algorithm\224-)f(by)h(which)h(an)f
(arbitrary)g(e)o(xpression)h(of)270 2567 y(the)g(relational)f(calculus)
h(can)g(be)g(reduced)f(to)h(a)g(semantically)f(equi)o(v)o(alent)g(e)o
(xpression)i(of)e(relational)270 2626 y(algebra.)j(F)o(or)d(a)h(more)f
(detailed)g(discussion)h(on)f(that)g(refer)g(to)g([D)n(A)-6
b(TE94)q(])12 b(and)g([ULL88].)345 2688 y(It)i(is)h(sometimes)g(said)g
(that)f(languages)h(based)g(on)g(the)f(relational)g(calculus)h(are)g
(\224higher)f(le)o(v)o(el\224)270 2748 y(or)e(\224more)g(declarati)o(v)
o(e\224)h(than)f(languages)h(based)g(on)f(relational)g(algebra)g
(because)h(the)g(algebra)f(\(par)o(-)270 2808 y(tially\))i(speci\002es)
h(the)g(order)f(of)g(operations)h(while)f(the)h(calculus)g(lea)o(v)o
(es)h(it)e(to)h(a)g(compiler)f(or)g(inter)o(-)270 2868
y(preter)e(to)g(determine)f(the)i(most)f(ef)o(\002cient)g(order)f(of)h
(e)o(v)o(aluation.)270 3048 y Fi(1.3)71 b(The)18 b(SQL)f(Language)270
3163 y Ft(As)11 b(most)f(modern)g(relational)f(languages)i(SQL)f(is)h
(based)g(on)f(the)g(tuple)g(relational)g(calculus.)15
b(As)c(a)g(re-)270 3223 y(sult)i(e)o(v)o(ery)f(query)g(that)h(can)g(be)
f(formulated)g(using)g(the)h(tuple)f(relational)g(calculus)h(\(or)f
(equi)o(v)o(alently)m(,)270 3283 y(relational)g(algebra\))h(can)g(also)
h(be)f(formulated)f(using)i(SQL.)g(There)f(are,)h(ho)o(we)o(v)o(er)n(,)
f(capabilities)g(be-)270 3342 y(yond)h(the)f(scope)i(of)e(relational)h
(algebra)f(or)h(calculus.)20 b(Here)14 b(is)g(a)h(list)e(of)h(some)g
(additional)f(features)270 3402 y(pro)o(vided)f(by)g(SQL)h(that)f(are)g
(not)g(part)g(of)g(relational)g(algebra)g(or)g(calculus:)p
eop
%%Page: 15 15
15 14 bop 198 60 a Fm(1.3.)29 b(THE)13 b(SQL)f(LANGU)n(A)n(GE)1160
b Ft(15)273 234 y Fo(\017)25 b Ft(Commands)12 b(for)f(insertion,)i
(deletion)f(or)g(modi\002cation)f(of)h(data.)273 333
y Fo(\017)25 b Ft(Arithmetic)12 b(capability:)17 b(In)c(SQL)h(it)g(is)f
(possible)h(to)g(in)n(v)o(olv)o(e)f(arithmetic)g(operations)g(as)h
(well)323 393 y(as)g(comparisons,)h(e.g.)22 b Fk(A)c(<)f(B)e
Fl(+)d(3)p Ft(.)21 b(Note)15 b(that)f Fl(+)g Ft(or)g(other)f
(arithmetic)h(operators)f(appear)323 453 y(neither)e(in)i(relational)e
(algebra)h(nor)g(in)g(relational)g(calculus.)273 552
y Fo(\017)25 b Ft(Assignment)14 b(and)g(Print)g(Commands:)19
b(It)14 b(is)g(possible)h(to)f(print)g(a)g(relation)g(constructed)g(by)
g(a)323 612 y(query)d(and)i(to)f(assign)h(a)g(computed)e(relation)h(to)
g(a)h(relation)f(name.)273 711 y Fo(\017)25 b Ft(Aggre)o(gate)15
b(Functions:)22 b(Operations)16 b(such)g(as)h Fp(aver)o(age)p
Ft(,)g Fp(sum)p Ft(,)h Fp(max)p Ft(,)f(.)7 b(.)g(.)g(can)19
b(be)d(applied)g(to)323 771 y(columns)c(of)g(a)g(relation)g(to)g
(obtain)g(a)h(single)f(quantity)m(.)198 913 y Fh(1.3.1)59
b(Select)198 1006 y Ft(The)17 b(most)f(often)g(used)h(command)f(in)g
(SQL)h(is)f(the)h(SELECT)h(statement)e(that)g(is)h(used)g(to)f(retrie)o
(v)o(e)198 1066 y(data.)g(The)d(syntax)f(is:)288 1165
y Fr(SELECT)29 b([ALL|DISTINCT])497 1225 y({)h(*)f(|)h(<expr_1>)f([AS)h
(<c_alias_1>])e([,)i(...)676 1285 y([,)g(<expr_k>)f([AS)g
(<c_alias_k>]]]})288 1344 y(FROM)g(<table_name_1>)f([t_alias_1])437
1404 y([,)i(...)f([,)h(<table_name_n>)e([t_alias_n]]])288
1464 y([WHERE)h(condition])288 1524 y([GROUP)g(BY)h(<name_of_attr_i>)
587 1583 y([,...)f([,)h(<name_of_attr_j>]])d([HAVING)j(condition]])288
1643 y([{UNION)f(|)h(INTERSECT)e(|)i(EXCEPT})f(SELECT)h(...])288
1703 y([ORDER)f(BY)h(<name_of_attr_i>)e([ASC|DESC])587
1763 y([,)h(...)h([,)f(<name_of_attr_j>)g([ASC|DESC]]]];)198
1861 y Ft(No)o(w)15 b(we)g(will)g(illustrate)g(the)g(comple)o(x)g
(syntax)g(of)g(the)g(SELECT)i(statement)f(with)f(v)o(arious)f(e)o(xam-)
198 1921 y(ples.)28 b(The)17 b(tables)g(used)f(for)g(the)g(e)o(xamples)
h(are)f(de\002ned)g(in)g(\002gure)g(1.1)h Fp(The)f(suppliers)g(and)h
(parts)198 1981 y(database)p Ft(.)198 2113 y Fn(Simple)12
b(Selects)198 2207 y(Example)h(1.5)25 b Ft(Here)12 b(are)g(some)h
(simple)f(e)o(xamples)h(using)f(a)h(SELECT)h(statement:)198
2326 y(T)l(o)23 b(retrie)o(v)o(e)f(all)h(tuples)g(from)f(table)g(P)-5
b(AR)m(T)24 b(where)f(the)f(attrib)o(ute)g(PRICE)h(is)g(greater)g(than)
f(10)198 2386 y(we)13 b(formulate)e(the)h(follo)o(wing)f(query)288
2485 y Fr(SELECT)29 b(*)288 2545 y(FROM)g(PART)288 2604
y(WHERE)g(PRICE)g(>)h(10;)198 2703 y Ft(and)12 b(get)h(the)f(table:)766
2802 y Fr(PNO)29 b(|)60 b(PNAME)f(|)h(PRICE)736 2862
y(-----+---------+--------)796 2921 y(3)f(|)h(Bolt)89
b(|)h(15)796 2981 y(4)59 b(|)h(Cam)119 b(|)90 b(25)198
3080 y Ft(Using)12 b(\224)p Fo(\003)p Ft(\224)g(in)g(the)g(SELECT)i
(statement)e(will)g(deli)o(v)o(er)f(all)h(attrib)o(utes)g(from)f(the)h
(table.)j(If)d(we)g(want)f(to)198 3140 y(retrie)o(v)o(e)h(only)g(the)g
(attrib)o(utes)g(PN)n(AME)h(and)f(PRICE)h(from)e(table)h(P)-5
b(AR)m(T)14 b(we)e(use)h(the)f(statement:)288 3238 y
Fr(SELECT)29 b(PNAME,)g(PRICE)288 3298 y(FROM)g(PART)288
3358 y(WHERE)g(PRICE)g(>)h(10;)p eop
%%Page: 16 16
16 15 bop 270 60 a Ft(16)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)270 234 y Ft(In)12 b(this)g(case)i(the)e(result)g(is:)928
339 y Fr(PNAME)59 b(|)g(PRICE)898 399 y(--------+--------)928
459 y(Bolt)89 b(|)g(15)928 519 y(Cam)119 b(|)89 b(25)270
622 y Ft(Note)12 b(that)f(the)h(SQL)g(SELECT)i(corresponds)e(to)f(the)h
(\224projection\224)f(in)h(relational)f(algebra)h(not)f(to)h(the)270
682 y(\224selection\224)h(\(see)f(section)h(1.2.1)g Fp(Relational)f
(Algebr)o(a)p Ft(\).)270 802 y(The)26 b(quali\002cations)g(in)g(the)f
(WHERE)i(clause)g(can)f(also)g(be)g(logically)f(connected)h(using)g
(the)270 862 y(ke)o(ywords)11 b(OR,)i(AND)g(and)f(NO)n(T)n(:)360
967 y Fr(SELECT)29 b(PNAME,)g(PRICE)360 1027 y(FROM)g(PART)360
1086 y(WHERE)g(PNAME)g(=)h('Bolt')f(AND)539 1146 y(\(PRICE)g(=)h(0)g
(OR)f(PRICE)h(<)g(15\);)270 1250 y Ft(will)12 b(lead)g(to)h(the)f
(result:)928 1355 y Fr(PNAME)59 b(|)g(PRICE)898 1415
y(--------+--------)928 1475 y(Bolt)89 b(|)g(15)270 1578
y Ft(Arithmetic)10 b(operations)g(may)h(be)g(used)g(in)g(the)f
Fp(selectlist)i Ft(and)e(in)h(the)g(WHERE)h(clause.)k(F)o(or)10
b(e)o(xample)270 1638 y(if)k(we)h(want)f(to)g(kno)o(w)h(ho)o(w)f(much)g
(it)g(would)g(cost)h(if)f(we)h(take)f(two)g(pieces)h(of)f(a)h(part)f
(we)h(could)g(use)270 1698 y(the)d(follo)o(wing)f(query:)360
1803 y Fr(SELECT)29 b(PNAME,)g(PRICE)g(*)h(2)g(AS)g(DOUBLE)360
1863 y(FROM)f(PART)360 1923 y(WHERE)g(PRICE)g(*)h(2)g(<)g(50;)270
2027 y Ft(and)12 b(we)h(get:)928 2132 y Fr(PNAME)59 b(|)g(DOUBLE)898
2191 y(--------+---------)928 2251 y(Screw)g(|)119 b(20)928
2311 y(Nut)g(|)g(16)928 2371 y(Bolt)89 b(|)119 b(30)270
2475 y Ft(Note)14 b(that)f(the)h(word)e(DOUBLE)j(after)e(the)g(ke)o
(yword)g(AS)g(is)h(the)g(ne)o(w)f(title)g(of)g(the)h(second)g(column.)
270 2534 y(This)i(technique)f(can)h(be)g(used)g(for)e(e)o(v)o(ery)h
(element)h(of)f(the)g Fp(selectlist)h Ft(to)g(assign)g(a)f(ne)o(w)h
(title)f(to)g(the)270 2594 y(resulting)i(column.)32 b(This)19
b(ne)o(w)f(title)f(is)i(often)e(referred)g(to)g(as)i(alias.)33
b(The)18 b(alias)h(cannot)f(be)g(used)270 2654 y(throughout)11
b(the)h(rest)h(of)f(the)g(query)m(.)270 2794 y Fn(J)o(oins)270
2890 y(Example)h(1.6)25 b Ft(The)13 b(follo)o(wing)e(e)o(xample)h(sho)o
(ws)h(ho)o(w)f Fp(joins)g Ft(are)g(realized)h(in)f(SQL:)270
3010 y(T)l(o)23 b(join)g(the)g(three)g(tables)g(SUPPLIER,)g(P)-5
b(AR)m(T)24 b(and)f(SELLS)h(o)o(v)o(er)f(their)f(common)h(attrib)o
(utes)270 3070 y(we)13 b(formulate)e(the)h(follo)o(wing)f(statement:)
360 3175 y Fr(SELECT)29 b(S.SNAME,)g(P.PNAME)360 3235
y(FROM)g(SUPPLIER)g(S,)h(PART)f(P,)h(SELLS)f(SE)360 3294
y(WHERE)g(S.SNO)g(=)h(SE.SNO)f(AND)539 3354 y(P.PNO)g(=)h(SE.PNO;)p
eop
%%Page: 17 17
17 16 bop 198 60 a Fm(1.3.)29 b(THE)13 b(SQL)f(LANGU)n(A)n(GE)1160
b Ft(17)198 234 y(and)12 b(get)h(the)f(follo)o(wing)f(table)h(as)h(a)g
(result:)885 330 y Fr(SNAME)30 b(|)g(PNAME)856 390 y(-------+-------)
885 450 y(Smith)g(|)g(Screw)885 510 y(Smith)g(|)g(Nut)885
570 y(Jones)g(|)g(Cam)885 629 y(Adams)g(|)g(Screw)885
689 y(Adams)g(|)g(Bolt)885 749 y(Blake)g(|)g(Nut)885
809 y(Blake)g(|)g(Bolt)885 868 y(Blake)g(|)g(Cam)198
965 y Ft(In)11 b(the)h(FR)n(OM)g(clause)g(we)g(introduced)f(an)h(alias)
g(name)g(for)f(e)o(v)o(ery)g(relation)g(because)i(there)e(are)h(com-)
198 1025 y(mon)j(named)g(attrib)o(utes)f(\(SNO)g(and)h(PNO\))g(among)f
(the)h(relations.)24 b(No)o(w)14 b(we)h(can)h(distinguish)e(be-)198
1084 y(tween)g(the)h(common)f(named)g(attrib)o(utes)g(by)g(simply)g
(pre\002xing)g(the)g(attrib)o(ute)g(name)g(with)g(the)h(alias)198
1144 y(name)f(follo)o(wed)e(by)i(a)g(dot.)20 b(The)14
b(join)g(is)g(calculated)g(in)f(the)h(same)g(way)g(as)g(sho)o(wn)g(in)f
(e)o(xample)h(1.1.)198 1204 y(First)d(the)g(Cartesian)h(product)e
Fk(S)s(U)5 b(P)i(P)g(LI)t(E)s(R)g Fo(\002)g Fk(P)g(ART)14
b Fo(\002)7 b Fk(S)s(E)s(LLS)12 b Ft(is)g(deri)o(v)o(ed.)j(No)o(w)c
(only)g(those)198 1264 y(tuples)i(satisfying)h(the)f(conditions)g(gi)o
(v)o(en)g(in)g(the)h(WHERE)g(clause)g(are)f(selected)h(\(i.e.)g(the)g
(common)198 1323 y(named)g(attrib)o(utes)f(ha)o(v)o(e)h(to)g(be)g
(equal\).)20 b(Finally)13 b(we)h(project)f(out)g(all)h(columns)g(b)o
(ut)f(S.SN)n(AME)i(and)198 1383 y(P)-6 b(.PN)n(AME.)198
1515 y Fn(Aggr)o(egate)12 b(Operators)198 1608 y Ft(SQL)k(pro)o(vides)f
(aggre)o(gate)g(operators)g(\(e.g.)25 b(A)-7 b(V)o(G,)16
b(COUNT)l(,)h(SUM,)f(MIN,)g(MAX\))f(that)g(take)g(the)198
1668 y(name)d(of)f(an)h(attrib)o(ute)f(as)i(an)f(ar)o(gument.)j(The)d
(v)o(alue)g(of)f(the)h(aggre)o(gate)g(operator)f(is)h(calculated)g(o)o
(v)o(er)198 1728 y(all)i(v)o(alues)g(of)g(the)g(speci\002ed)g(attrib)o
(ute)f(\(column\))g(of)g(the)h(whole)g(table.)21 b(If)13
b(groups)h(are)g(speci\002ed)g(in)198 1788 y(the)e(query)g(the)h
(calculation)f(is)g(done)h(only)f(o)o(v)o(er)g(the)g(v)o(alues)h(of)f
(a)g(group)g(\(see)h(ne)o(xt)f(section\).)198 1905 y
Fn(Example)h(1.7)25 b Ft(If)15 b(we)h(want)f(to)g(kno)o(w)h(the)f(a)o
(v)o(erage)h(cost)h(of)e(all)g(parts)h(in)g(table)f(P)-5
b(AR)m(T)17 b(we)f(use)g(the)198 1965 y(follo)o(wing)11
b(query:)288 2061 y Fr(SELECT)29 b(AVG\(PRICE\))g(AS)g(AVG_PRICE)288
2121 y(FROM)g(PART;)198 2217 y Ft(The)13 b(result)f(is:)945
2313 y Fr(AVG_PRICE)915 2373 y(-----------)1005 2433
y(14.5)198 2529 y Ft(If)g(we)g(want)g(to)g(kno)o(w)g(ho)o(w)g(man)o(y)g
(parts)h(are)f(stored)g(in)g(table)h(P)-5 b(AR)m(T)13
b(we)f(use)h(the)g(statement:)288 2626 y Fr(SELECT)29
b(COUNT\(PNO\))288 2685 y(FROM)g(PART;)198 2782 y Ft(and)12
b(get:)1005 2878 y Fr(COUNT)975 2938 y(-------)1065 2998
y(4)198 3130 y Fn(Aggr)o(egation)f(by)h(Gr)o(oups)198
3223 y Ft(SQL)18 b(allo)o(ws)f(to)h(partition)f(the)g(tuples)h(of)f(a)h
(table)g(into)f(groups.)31 b(Then)19 b(the)e(aggre)o(gate)h(operators)
198 3283 y(described)12 b(abo)o(v)o(e)i(can)e(be)h(applied)f(to)g(the)h
(groups)f(\(i.e.)k(the)d(v)o(alue)f(of)g(the)h(aggre)o(gate)f(operator)
f(is)i(no)198 3342 y(longer)f(calculated)g(o)o(v)o(er)h(all)f(the)h(v)o
(alues)f(of)g(the)g(speci\002ed)h(column)f(b)o(ut)g(o)o(v)o(er)h(all)f
(v)o(alues)h(of)f(a)g(group.)198 3402 y(Thus)h(the)f(aggre)o(gate)g
(operator)g(is)h(e)o(v)o(aluated)e(indi)o(vidually)g(for)h(e)o(v)o(ery)
g(group.\))p eop
%%Page: 18 18
18 17 bop 270 60 a Ft(18)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)270 294 y Ft(The)21 b(partitioning)e(of)h(the)g(tuples)h(into)f
(groups)g(is)h(done)f(by)g(using)h(the)f(ke)o(ywords)g(GR)n(OUP)12
b(BY)270 354 y(follo)o(wed)g(by)h(a)g(list)g(of)g(attrib)o(utes)f(that)
h(de\002ne)g(the)g(groups.)18 b(If)12 b(we)h(ha)o(v)o(e)h
Fr(GROUP)29 b(BY)h Fk(A)1875 361 y Fg(1)1897 354 y Fk(;)8
b(:)g(:)g(:)h(;)f(A)2045 361 y Ff(k)270 413 y Ft(we)k(partition)f(the)h
(relation)f(into)h(groups,)g(such)g(that)g(two)f(tuples)i(are)e(in)h
(the)g(same)h(group)e(if)g(and)h(only)270 473 y(if)g(the)o(y)g(agree)h
(on)f(all)g(the)h(attrib)o(utes)e Fk(A)962 480 y Fg(1)985
473 y Fk(;)d(:)g(:)g(:)h(;)f(A)1133 480 y Ff(k)1158 473
y Ft(.)270 600 y Fn(Example)13 b(1.8)25 b Ft(If)11 b(we)h(want)g(to)g
(kno)o(w)g(ho)o(w)f(man)o(y)h(parts)g(are)g(sold)h(by)f(e)o(v)o(ery)f
(supplier)h(we)g(formulate)270 660 y(the)g(query:)360
764 y Fr(SELECT)29 b(S.SNO,)g(S.SNAME,)g(COUNT\(SE.PNO\))360
824 y(FROM)g(SUPPLIER)g(S,)h(SELLS)f(SE)360 883 y(WHERE)g(S.SNO)g(=)h
(SE.SNO)360 943 y(GROUP)f(BY)h(S.SNO,)f(S.SNAME;)270
1046 y Ft(and)12 b(get:)898 1151 y Fr(SNO)29 b(|)h(SNAME)f(|)h(COUNT)
868 1210 y(-----+-------+-------)928 1270 y(1)59 b(|)30
b(Smith)f(|)90 b(2)928 1330 y(2)59 b(|)30 b(Jones)f(|)90
b(1)928 1390 y(3)59 b(|)30 b(Adams)f(|)90 b(2)928 1450
y(4)59 b(|)30 b(Blake)f(|)90 b(3)270 1553 y Ft(No)o(w)12
b(let')m(s)h(ha)o(v)o(e)f(a)h(look)f(of)g(what)g(is)h(happening)f
(here:)270 1612 y(First)g(the)g(join)g(of)g(the)g(tables)h(SUPPLIER)f
(and)h(SELLS)g(is)f(deri)o(v)o(ed:)808 1717 y Fr(S.SNO)29
b(|)h(S.SNAME)f(|)h(SE.PNO)778 1777 y(-------+---------+--------)868
1836 y(1)89 b(|)60 b(Smith)f(|)90 b(1)868 1896 y(1)f(|)60
b(Smith)f(|)90 b(2)868 1956 y(2)f(|)60 b(Jones)f(|)90
b(4)868 2016 y(3)f(|)60 b(Adams)f(|)90 b(1)868 2075 y(3)f(|)60
b(Adams)f(|)90 b(3)868 2135 y(4)f(|)60 b(Blake)f(|)90
b(2)868 2195 y(4)f(|)60 b(Blake)f(|)90 b(3)868 2255 y(4)f(|)60
b(Blake)f(|)90 b(4)270 2358 y Ft(Ne)o(xt)16 b(we)g(partition)f(the)h
(tuples)g(into)f(groups)h(by)g(putting)f(all)h(tuples)g(together)f
(that)h(agree)g(on)f(both)270 2418 y(attrib)o(utes)d(S.SNO)g(and)g
(S.SN)n(AME:)808 2522 y Fr(S.SNO)29 b(|)h(S.SNAME)f(|)h(SE.PNO)778
2582 y(-------+---------+--------)868 2642 y(1)89 b(|)60
b(Smith)f(|)90 b(1)1286 2701 y(|)g(2)778 2761 y
(--------------------------)868 2821 y(2)f(|)60 b(Jones)f(|)90
b(4)778 2881 y(--------------------------)868 2940 y(3)f(|)60
b(Adams)f(|)90 b(1)1286 3000 y(|)g(3)778 3060 y
(--------------------------)868 3120 y(4)f(|)60 b(Blake)f(|)90
b(2)1286 3180 y(|)g(3)1286 3239 y(|)g(4)270 3342 y Ft(In)13
b(our)f(e)o(xample)i(we)f(got)g(four)f(groups)h(and)g(no)o(w)g(we)g
(can)g(apply)g(the)g(aggre)o(gate)g(operator)f(COUNT)270
3402 y(to)g(e)o(v)o(ery)g(group)g(leading)g(to)g(the)h(total)f(result)g
(of)g(the)g(query)g(gi)o(v)o(en)g(abo)o(v)o(e.)p eop
%%Page: 19 19
19 18 bop 198 60 a Fm(1.3.)29 b(THE)13 b(SQL)f(LANGU)n(A)n(GE)1160
b Ft(19)198 234 y(Note)11 b(that)f(for)g(the)h(result)g(of)f(a)h(query)
f(using)h(GR)n(OUP)g(BY)g(and)g(aggre)o(gate)f(operators)g(to)h(make)f
(sense)198 294 y(the)16 b(attrib)o(utes)f(grouped)h(by)f(must)h(also)h
(appear)e(in)h(the)g Fp(selectlist)p Ft(.)27 b(All)16
b(further)e(attrib)o(utes)i(not)f(ap-)198 354 y(pearing)d(in)g(the)g
(GR)n(OUP)g(BY)h(clause)g(can)f(only)g(be)h(selected)f(by)h(using)f(an)
g(aggre)o(gate)g(function.)j(On)198 413 y(the)f(other)f(hand)g(you)g
(can)h(not)f(use)h(aggre)o(gate)g(functions)f(on)g(attrib)o(utes)g
(appearing)g(in)h(the)f(GR)n(OUP)198 473 y(BY)g(clause.)198
606 y Fn(Ha)o(ving)198 699 y Ft(The)18 b(HA)-7 b(VING)17
b(clause)i(works)e(much)g(like)g(the)g(WHERE)i(clause)f(and)g(is)g
(used)g(to)f(consider)g(only)198 759 y(those)h(groups)g(satisfying)f
(the)h(quali\002cation)f(gi)o(v)o(en)h(in)g(the)f(HA)-7
b(VING)18 b(clause.)33 b(The)18 b(e)o(xpressions)198
818 y(allo)o(wed)13 b(in)h(the)g(HA)-7 b(VING)13 b(clause)i(must)e(in)n
(v)o(olv)o(e)h(aggre)o(gate)f(functions.)20 b(Ev)o(ery)14
b(e)o(xpression)g(using)198 878 y(only)h(plain)h(attrib)o(utes)f
(belongs)h(to)g(the)g(WHERE)h(clause.)27 b(On)15 b(the)h(other)f(hand)h
(e)o(v)o(ery)g(e)o(xpression)198 938 y(in)n(v)o(olving)11
b(an)i(aggre)o(gate)f(function)f(must)i(be)f(put)g(to)h(the)f(HA)-7
b(VING)12 b(clause.)198 1056 y Fn(Example)h(1.9)25 b
Ft(If)11 b(we)h(want)f(only)h(those)g(suppliers)g(selling)g(more)f
(than)h(one)g(part)f(we)h(use)h(the)f(query:)288 1155
y Fr(SELECT)29 b(S.SNO,)g(S.SNAME,)g(COUNT\(SE.PNO\))288
1214 y(FROM)g(SUPPLIER)g(S,)h(SELLS)f(SE)288 1274 y(WHERE)g(S.SNO)g(=)h
(SE.SNO)288 1334 y(GROUP)f(BY)h(S.SNO,)f(S.SNAME)288
1394 y(HAVING)g(COUNT\(SE.PNO\))f(>)i(1;)198 1492 y Ft(and)12
b(get:)826 1590 y Fr(SNO)29 b(|)h(SNAME)f(|)h(COUNT)796
1650 y(-----+-------+-------)856 1709 y(1)59 b(|)30 b(Smith)f(|)90
b(2)856 1769 y(3)59 b(|)30 b(Adams)f(|)90 b(2)856 1829
y(4)59 b(|)30 b(Blake)f(|)90 b(3)198 1961 y Fn(Subqueries)198
2055 y Ft(In)11 b(the)g(WHERE)i(and)e(HA)-7 b(VING)12
b(clauses)g(the)f(use)h(of)f(subqueries)h(\(subselects\))f(is)h(allo)o
(wed)f(in)g(e)o(v)o(ery)198 2114 y(place)k(where)g(a)g(v)o(alue)g(is)g
(e)o(xpected.)24 b(In)14 b(this)h(case)h(the)f(v)o(alue)g(must)g(be)g
(deri)o(v)o(ed)f(by)h(e)o(v)o(aluating)f(the)198 2174
y(subquery)e(\002rst.)j(The)e(usage)g(of)f(subqueries)h(e)o(xtends)g
(the)f(e)o(xpressi)o(v)o(e)h(po)o(wer)f(of)g(SQL.)198
2293 y Fn(Example)h(1.10)25 b Ft(If)17 b(we)h(want)g(to)f(kno)o(w)h
(all)g(parts)g(ha)o(ving)g(a)g(greater)f(price)h(than)g(the)g(part)f
(named)198 2352 y('Scre)o(w')11 b(we)h(use)h(the)g(query:)288
2450 y Fr(SELECT)29 b(*)288 2510 y(FROM)g(PART)288 2570
y(WHERE)g(PRICE)g(>)h(\(SELECT)f(PRICE)h(FROM)f(PART)736
2630 y(WHERE)g(PNAME='Screw'\);)198 2728 y Ft(The)13
b(result)f(is:)766 2826 y Fr(PNO)29 b(|)60 b(PNAME)f(|)h(PRICE)736
2886 y(-----+---------+--------)796 2945 y(3)f(|)h(Bolt)89
b(|)h(15)796 3005 y(4)59 b(|)h(Cam)119 b(|)90 b(25)198
3103 y Ft(When)15 b(we)g(look)g(at)g(the)g(abo)o(v)o(e)h(query)e(we)h
(can)h(see)f(the)g(ke)o(yword)f(SELECT)j(two)d(times.)24
b(The)15 b(\002rst)198 3163 y(one)h(at)g(the)f(be)o(ginning)h(of)f(the)
h(query)f(-)h(we)g(will)f(refer)g(to)h(it)f(as)i(outer)e(SELECT)i(-)f
(and)g(the)f(one)h(in)198 3223 y(the)h(WHERE)h(clause)g(which)f(be)o
(gins)h(a)f(nested)h(query)e(-)h(we)g(will)g(refer)f(to)h(it)g(as)h
(inner)f(SELECT)l(.)198 3283 y(F)o(or)d(e)o(v)o(ery)g(tuple)g(of)g(the)
g(outer)g(SELECT)i(the)e(inner)g(SELECT)i(has)f(to)f(be)h(e)o(v)o
(aluated.)21 b(After)13 b(e)o(v)o(ery)198 3342 y(e)o(v)o(aluation)f(we)
i(kno)o(w)f(the)g(price)g(of)g(the)g(tuple)g(named)h('Scre)o(w')d(and)j
(we)f(can)h(check)f(if)g(the)h(price)f(of)198 3402 y(the)f(actual)h
(tuple)f(is)g(greater)m(.)p eop
%%Page: 20 20
20 19 bop 270 60 a Ft(20)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)270 294 y Ft(If)19 b(we)i(want)f(to)g(kno)o(w)f(all)i(suppliers)f
(that)g(do)g(not)g(sell)g(an)o(y)h(part)f(\(e.g.)39 b(to)20
b(be)h(able)f(to)g(remo)o(v)o(e)270 354 y(these)13 b(suppliers)f(from)f
(the)i(database\))f(we)h(use:)360 471 y Fr(SELECT)29
b(*)360 531 y(FROM)g(SUPPLIER)g(S)360 590 y(WHERE)g(NOT)h(EXISTS)659
650 y(\(SELECT)f(*)g(FROM)h(SELLS)f(SE)688 710 y(WHERE)h(SE.SNO)f(=)h
(S.SNO\);)270 823 y Ft(In)19 b(our)h(e)o(xample)g(the)g(result)f(will)h
(be)g(empty)f(because)i(e)o(v)o(ery)e(supplier)h(sells)g(at)g(least)g
(one)g(part.)270 883 y(Note)15 b(that)g(we)g(use)h(S.SNO)e(from)g(the)h
(outer)g(SELECT)i(within)d(the)h(WHERE)h(clause)g(of)f(the)g(inner)270
942 y(SELECT)l(.)d(As)f(described)f(abo)o(v)o(e)g(the)g(subquery)g(is)g
(e)o(v)o(aluated)f(for)g(e)o(v)o(ery)h(tuple)g(from)e(the)i(outer)g
(query)270 1002 y(i.e.)16 b(the)d(v)o(alue)f(for)f(S.SNO)i(is)f(always)
g(taken)g(from)f(the)h(actual)h(tuple)f(of)g(the)g(outer)g(SELECT)l(.)
270 1159 y Fn(Union,)g(Intersect,)h(Except)270 1261 y
Ft(These)19 b(operations)e(calculate)h(the)g(union,)i(intersect)d(and)h
(set)h(theoretic)e(dif)o(ference)g(of)g(the)h(tuples)270
1320 y(deri)o(v)o(ed)12 b(by)g(two)g(subqueries:)270
1466 y Fn(Example)h(1.11)25 b Ft(The)13 b(follo)o(wing)e(query)g(is)i
(an)g(e)o(xample)f(for)g(UNION:)360 1583 y Fr(SELECT)29
b(S.SNO,)g(S.SNAME,)g(S.CITY)360 1643 y(FROM)g(SUPPLIER)g(S)360
1703 y(WHERE)g(S.SNAME)g(=)h('Jones')360 1763 y(UNION)360
1822 y(SELECT)f(S.SNO,)g(S.SNAME,)g(S.CITY)360 1882 y(FROM)g(SUPPLIER)g
(S)360 1942 y(WHERE)g(S.SNAME)g(=)h('Adams';)270 2055
y Ft(gi)o(v)o(es)13 b(the)f(result:)898 2172 y Fr(SNO)29
b(|)h(SNAME)f(|)60 b(CITY)868 2232 y(-----+-------+--------)928
2292 y(2)f(|)30 b(Jones)f(|)h(Paris)928 2351 y(3)59 b(|)30
b(Adams)f(|)h(Vienna)270 2464 y Ft(Here)12 b(an)h(e)o(xample)f(for)g
(INTERSECT)n(:)360 2581 y Fr(SELECT)29 b(S.SNO,)g(S.SNAME,)g(S.CITY)360
2641 y(FROM)g(SUPPLIER)g(S)360 2701 y(WHERE)g(S.SNO)g(>)h(1)360
2761 y(INTERSECT)360 2820 y(SELECT)f(S.SNO,)g(S.SNAME,)g(S.CITY)360
2880 y(FROM)g(SUPPLIER)g(S)360 2940 y(WHERE)g(S.SNO)g(>)h(2;)270
3053 y Ft(gi)o(v)o(es)13 b(the)f(result:)898 3170 y Fr(SNO)29
b(|)h(SNAME)f(|)60 b(CITY)868 3230 y(-----+-------+--------)928
3289 y(2)f(|)30 b(Jones)f(|)h(Paris)270 3402 y Ft(The)13
b(only)f(tuple)g(returned)f(by)i(both)f(parts)g(of)g(the)g(query)g(is)h
(the)f(one)h(ha)o(ving)f Fk(S)s(N)5 b(O)15 b Fl(=)e(2)p
Ft(.)p eop
%%Page: 21 21
21 20 bop 198 60 a Fm(1.3.)29 b(THE)13 b(SQL)f(LANGU)n(A)n(GE)1160
b Ft(21)198 234 y(Finally)12 b(an)g(e)o(xample)h(for)e(EXCEPT)n(:)288
342 y Fr(SELECT)29 b(S.SNO,)g(S.SNAME,)g(S.CITY)288 402
y(FROM)g(SUPPLIER)g(S)288 461 y(WHERE)g(S.SNO)g(>)h(1)288
521 y(EXCEPT)288 581 y(SELECT)f(S.SNO,)g(S.SNAME,)g(S.CITY)288
641 y(FROM)g(SUPPLIER)g(S)288 700 y(WHERE)g(S.SNO)g(>)h(3;)198
806 y Ft(gi)o(v)o(es)13 b(the)f(result:)826 914 y Fr(SNO)29
b(|)h(SNAME)f(|)60 b(CITY)796 974 y(-----+-------+--------)856
1033 y(2)f(|)30 b(Jones)f(|)h(Paris)856 1093 y(3)59 b(|)30
b(Adams)f(|)h(Vienna)198 1247 y Fh(1.3.2)59 b(Data)15
b(De\002nition)198 1344 y Ft(There)e(is)f(a)h(set)g(of)f(commands)g
(used)h(for)e(data)i(de\002nition)e(included)h(in)g(the)h(SQL)f
(language.)198 1488 y Fn(Cr)o(eate)g(T)-5 b(able)198
1585 y Ft(The)12 b(most)g(fundamental)e(command)h(for)g(data)h
(de\002nition)e(is)i(the)g(one)f(that)g(creates)h(a)g(ne)o(w)f
(relation)g(\(a)198 1645 y(ne)o(w)h(table\).)k(The)c(syntax)h(of)f(the)
g(CREA)-6 b(TE)15 b(T)-5 b(ABLE)14 b(command)e(is:)288
1752 y Fr(CREATE)29 b(TABLE)g(<table_name>)676 1812 y
(\(<name_of_attr_1>)f(<type_of_attr_1>)706 1872 y([,)i
(<name_of_attr_2>)e(<type_of_attr_2>)706 1932 y([,)i(...]]\);)198
2063 y Fn(Example)13 b(1.12)25 b Ft(T)l(o)13 b(create)g(the)g(tables)h
(de\002ned)e(in)h(\002gure)g(1.1)g(the)g(follo)o(wing)f(SQL)h
(statements)g(are)198 2123 y(used:)288 2231 y Fr(CREATE)29
b(TABLE)g(SUPPLIER)676 2290 y(\(SNO)89 b(INTEGER,)706
2350 y(SNAME)29 b(VARCHAR\(20\),)706 2410 y(CITY)59 b(VARCHAR\(20\)\);)
288 2530 y(CREATE)29 b(TABLE)g(PART)676 2589 y(\(PNO)89
b(INTEGER,)706 2649 y(PNAME)29 b(VARCHAR\(20\),)706 2709
y(PRICE)g(DECIMAL\(4)g(,)h(2\)\);)288 2828 y(CREATE)f(TABLE)g(SELLS)676
2888 y(\(SNO)h(INTEGER,)706 2948 y(PNO)g(INTEGER\);)198
3092 y Fn(Data)12 b(T)l(ypes)h(in)f(SQL)198 3189 y Ft(The)h(follo)o
(wing)e(is)i(a)f(list)g(of)g(some)h(data)f(types)h(that)f(are)h
(supported)e(by)i(SQL:)273 3295 y Fo(\017)25 b Ft(INTEGER:)13
b(signed)f(fullword)e(binary)i(inte)o(ger)g(\(31)g(bits)g(precision\).)
273 3402 y Fo(\017)25 b Ft(SMALLINT)n(:)12 b(signed)h(halfword)d
(binary)i(inte)o(ger)g(\(15)g(bits)g(precision\).)p eop
%%Page: 22 22
22 21 bop 270 60 a Ft(22)1354 b Fm(CHAPTER)14 b(1.)25
b(SQL)345 234 y Fo(\017)g Ft(DECIMAL)19 b(\()p Fk(p)p
Fl([)p Fk(;)8 b(q)r Fl(])p Ft(\):)27 b(signed)19 b(packed)f(decimal)h
(number)f(of)g Fk(p)h Ft(digits)f(precision)h(with)f(as-)395
294 y(sumed)13 b Fk(q)j Ft(of)e(them)f(right)g(to)h(the)g(decimal)f
(point.)20 b Fl(\(15)d Fo(\025)f Fk(p)g Fo(\025)h Fk(q)h
Fo(\025)e Fl(0\))p Ft(.)21 b(If)13 b Fk(q)j Ft(is)e(omitted)f(it)h(is)
395 354 y(assumed)f(to)f(be)g(0.)345 448 y Fo(\017)25
b Ft(FLO)n(A)-6 b(T)n(:)13 b(signed)f(double)o(word)f(\003oating)g
(point)h(number)m(.)345 543 y Fo(\017)25 b Ft(CHAR\()p
Fk(n)p Ft(\):)14 b(\002x)o(ed)f(length)f(character)g(string)f(of)h
(length)g Fk(n)p Ft(.)345 638 y Fo(\017)25 b Ft(V)-7
b(ARCHAR\()p Fk(n)p Ft(\):)15 b(v)o(arying)c(length)h(character)g
(string)g(of)g(maximum)f(length)h Fk(n)p Ft(.)270 768
y Fn(Cr)o(eate)g(Index)270 862 y Ft(Indices)i(are)g(used)h(to)f(speed)h
(up)f(access)i(to)e(a)g(relation.)21 b(If)14 b(a)g(relation)g
Fk(R)g Ft(has)h(an)f(inde)o(x)h(on)f(attrib)o(ute)270
921 y Fk(A)j Ft(then)f(we)h(can)f(retrie)o(v)o(e)g(all)g(tuples)h
Fk(t)g Ft(ha)o(ving)f Fk(t)p Fl(\()p Fk(A)p Fl(\))22
b(=)f Fk(a)c Ft(in)f(time)h(roughly)e(proportional)g(to)h(the)270
981 y(number)c(of)g(such)g(tuples)h Fk(t)f Ft(rather)g(than)g(in)g
(time)g(proportional)f(to)h(the)h(size)f(of)g Fk(R)p
Ft(.)345 1041 y(T)l(o)h(create)f(an)g(inde)o(x)h(in)f(SQL)h(the)f(CREA)
-6 b(TE)14 b(INDEX)f(command)f(is)g(used.)17 b(The)c(syntax)f(is:)360
1131 y Fr(CREATE)29 b(INDEX)g(<index_name>)360 1190 y(ON)g
(<table_name>)g(\()h(<name_of_attribute>)d(\);)270 1303
y Fn(Example)13 b(1.13)25 b Ft(T)l(o)12 b(create)g(an)f(inde)o(x)h
(named)g(I)f(on)h(attrib)o(ute)f(SN)n(AME)h(of)f(relation)g(SUPPLIER)h
(we)270 1362 y(use)h(the)f(follo)o(wing)f(statement:)360
1452 y Fr(CREATE)29 b(INDEX)g(I)360 1512 y(ON)g(SUPPLIER)g(\(SNAME\);)
270 1602 y Ft(The)11 b(created)f(inde)o(x)h(is)g(maintained)f
(automatically)m(,)g(i.e.)i(whene)o(v)o(er)e(a)g(ne)o(w)h(tuple)f(is)h
(inserted)f(into)g(the)270 1661 y(relation)k(SUPPLIER)g(the)h(inde)o(x)
f(I)h(is)g(adapted.)22 b(Note)15 b(that)f(the)h(only)f(changes)h(a)g
(user)g(can)f(percept)270 1721 y(when)e(an)h(inde)o(x)f(is)h(present)f
(are)g(an)h(increased)g(speed.)270 1852 y Fn(Cr)o(eate)f(V)n(iew)270
1945 y Ft(A)i(vie)o(w)f(may)h(be)g(re)o(garded)f(as)h(a)g
Fp(virtual)g(table)p Ft(,)g(i.e.)h(a)f(table)f(that)h(does)g(not)g
Fp(physically)f Ft(e)o(xist)i(in)e(the)270 2005 y(database)i(b)o(ut)f
(looks)g(to)g(the)g(user)g(as)h(if)e(it)h(did.)21 b(By)14
b(contrast,)h(when)f(we)g(talk)g(of)g(a)g Fp(base)h(table)e
Ft(there)270 2064 y(is)f(really)g(a)g(physically)f(stored)h
(counterpart)e(of)i(each)g(ro)o(w)f(of)h(the)f(table)h(some)o(where)g
(in)f(the)h(physical)270 2124 y(storage.)345 2184 y(V)m(ie)o(ws)h(do)g
(not)g(ha)o(v)o(e)h(their)f(o)o(wn,)h(physically)e(separate,)j
(distinguishable)e(stored)g(data.)19 b(Instead,)270 2244
y(the)d(system)g(stores)g(the)f Fp(de\002nition)g Ft(of)h(the)f(vie)o
(w)h(\(i.e.)g(the)g(rules)f(about)h(ho)o(w)f(to)g(access)i(physically)
270 2304 y(stored)c Fp(base)g(tables)h Ft(in)e(order)h(to)g
(materialize)f(the)h(vie)o(w\))g(some)o(where)f(in)h(the)g
Fp(system)h(catalogs)f Ft(\(see)270 2363 y(section)19
b(1.3.4)h Fp(System)g(Catalogs)p Ft(\).)36 b(F)o(or)18
b(a)i(discussion)g(on)f(dif)o(ferent)e(techniques)j(to)f(implement)270
2423 y(vie)o(ws)12 b(refer)g(to)g(section)h(3.4.1)g Fp(T)-5
b(ec)o(hniques)13 b(T)-5 b(o)12 b(Implement)g(V)l(ie)o(ws)p
Ft(.)345 2483 y(In)g(SQL)g(the)h(CREA)-6 b(TE)14 b(VIEW)f(command)f(is)
g(used)h(to)f(de\002ne)g(a)h(vie)o(w)m(.)i(The)e(syntax)g(is:)360
2573 y Fr(CREATE)29 b(VIEW)g(<view_name>)360 2632 y(AS)g(<select_stmt>)
270 2722 y Ft(where)10 b Fk(<)p Fr(select)p 624 2722
15 2 v 17 w(stmt)p Fk(>)40 b Ft(is)11 b(a)g(v)o(alid)g(select)g
(statement)f(as)i(de\002ned)e(in)h(section)g(1.3.1.)16
b(Note)10 b(that)270 2782 y(the)15 b Fk(<)p Fr(select)p
568 2782 V 17 w(stmt)p Fk(>)44 b Ft(is)15 b(not)g(e)o(x)o(ecuted)g
(when)g(the)g(vie)o(w)f(is)h(created.)23 b(It)15 b(is)g(just)g(stored)f
(in)h(the)270 2842 y Fp(system)e(catalogs)f Ft(and)g(is)h(e)o(x)o
(ecuted)g(whene)o(v)o(er)f(a)h(query)f(against)g(the)g(vie)o(w)g(is)h
(made.)270 2954 y Fn(Example)g(1.14)25 b Ft(Let)16 b(the)g(follo)o
(wing)f(vie)o(w)h(de\002nition)f(be)h(gi)o(v)o(en)g(\(we)g(use)g(the)g
(tables)h(from)e(\002gure)270 3014 y(1.1)e Fp(The)f(suppliers)h(and)f
(parts)h(database)f Ft(again\):)360 3103 y Fr(CREATE)29
b(VIEW)g(London_Suppliers)449 3163 y(AS)h(SELECT)f(S.SNAME,)g(P.PNAME)
539 3223 y(FROM)g(SUPPLIER)g(S,)h(PART)g(P,)f(SELLS)h(SE)539
3283 y(WHERE)f(S.SNO)h(=)f(SE.SNO)h(AND)718 3342 y(P.PNO)g(=)f(SE.PNO)h
(AND)718 3402 y(S.CITY)g(=)f('London';)p eop
%%Page: 23 23
23 22 bop 198 60 a Fm(1.3.)26 b(THE)13 b(SQL)f(LANGU)n(A)n(GE)1163
b Ft(23)198 234 y(No)o(w)10 b(we)g(can)g(use)g(this)g
Fp(virtual)g(r)n(elation)f Fr(London)p 1100 234 15 2
v 18 w(Suppliers)g Ft(as)h(if)f(it)h(were)g(another)f(base)h(table:)288
338 y Fr(SELECT)29 b(*)288 397 y(FROM)g(London_Suppliers)288
457 y(WHERE)g(P.PNAME)g(=)h('Screw';)198 560 y Ft(will)12
b(return)f(the)i(follo)o(wing)e(table:)885 663 y Fr(SNAME)30
b(|)g(PNAME)856 723 y(-------+-------)885 783 y(Smith)g(|)g(Screw)198
885 y Ft(T)l(o)17 b(calculate)h(this)f(result)g(the)g(database)g
(system)h(has)f(to)g(do)g(a)g Fp(hidden)g Ft(access)h(to)f(the)g(base)h
(tables)198 945 y(SUPPLIER,)e(SELLS)g(and)g(P)-5 b(AR)m(T)16
b(\002rst.)25 b(It)15 b(does)h(so)g(by)f(e)o(x)o(ecuting)h(the)f(query)
g(gi)o(v)o(en)h(in)f(the)g(vie)o(w)198 1005 y(de\002nition)h(against)g
(those)h(base)h(tables.)28 b(After)16 b(that)h(the)f(additional)g
(quali\002cations)h(\(gi)o(v)o(en)f(in)g(the)198 1065
y(query)c(against)g(the)h(vie)o(w\))e(can)i(be)f(applied)g(to)h(obtain)
f(the)g(resulting)g(table.)198 1202 y Fn(Dr)o(op)g(T)-5
b(able,)13 b(Dr)o(op)g(Index,)f(Dr)o(op)h(V)n(iew)198
1298 y Ft(T)l(o)g(destroy)e(a)h(table)h(\(including)e(all)h(tuples)g
(stored)g(in)g(that)g(table\))g(the)g(DR)n(OP)g(T)-5
b(ABLE)14 b(command)e(is)198 1357 y(used:)288 1461 y
Fr(DROP)29 b(TABLE)g(<table_name>;)198 1586 y Fn(Example)13
b(1.15)25 b Ft(T)l(o)13 b(destroy)e(the)h(SUPPLIER)h(table)f(use)h(the)
f(follo)o(wing)f(statement:)288 1690 y Fr(DROP)29 b(TABLE)g(SUPPLIER;)
198 1792 y Ft(The)13 b(DR)n(OP)f(INDEX)h(command)f(is)g(used)h(to)f
(destroy)g(an)g(inde)o(x:)288 1896 y Fr(DROP)29 b(INDEX)g
(<index_name>;)198 1998 y Ft(Finally)12 b(to)g(destroy)f(a)i(gi)o(v)o
(en)f(vie)o(w)g(use)h(the)f(command)g(DR)n(OP)h(VIEW)n(:)288
2102 y Fr(DROP)29 b(VIEW)h(<view_name>;)198 2250 y Fh(1.3.3)59
b(Data)15 b(Manipulation)198 2345 y Fn(Insert)e(Into)198
2440 y Ft(Once)h(a)h(table)f(is)h(created)f(\(see)g(section)h(1.3.2\),)
g(it)f(can)h(be)f(\002lled)g(with)g(tuples)g(using)g(the)h(command)198
2500 y(INSER)m(T)e(INT)o(O.)g(The)g(syntax)f(is:)288
2603 y Fr(INSERT)29 b(INTO)g(<table_name>)g(\(<name_of_attr_1>)1065
2663 y([,)g(<name_of_attr_2>)g([,...]]\))288 2723 y(VALUES)g
(\(<val_attr_1>)527 2783 y([,)g(<val_attr_2>)g([,)h(...]]\);)198
2908 y Fn(Example)13 b(1.16)25 b Ft(T)l(o)14 b(insert)g(the)h(\002rst)f
(tuple)f(into)h(the)h(relation)e(SUPPLIER)h(of)g(\002gure)g(1.1)g
Fp(The)g(sup-)198 2968 y(pliers)e(and)h(parts)f(database)h
Ft(we)f(use)h(the)g(follo)o(wing)d(statement:)288 3071
y Fr(INSERT)29 b(INTO)g(SUPPLIER)g(\(SNO,)h(SNAME,)f(CITY\))288
3131 y(VALUES)g(\(1,)g('Smith',)g('London'\);)198 3234
y Ft(T)l(o)13 b(insert)f(the)g(\002rst)g(tuple)g(into)g(the)h(relation)
e(SELLS)i(we)g(use:)288 3337 y Fr(INSERT)29 b(INTO)g(SELLS)h(\(SNO,)f
(PNO\))288 3397 y(VALUES)g(\(1,)g(1\);)p eop
%%Page: 24 24
24 23 bop 270 60 a Ft(24)1351 b Fm(CHAPTER)14 b(1.)28
b(SQL)270 234 y Fn(Update)270 330 y Ft(T)l(o)17 b(change)f(one)h(or)f
(more)g(attrib)o(ute)f(v)o(alues)i(of)f(tuples)g(in)h(a)f(relation)g
(the)g(UPD)n(A)-6 b(TE)18 b(command)e(is)270 389 y(used.)g(The)d
(syntax)g(is:)360 493 y Fr(UPDATE)29 b(<table_name>)360
553 y(SET)g(<name_of_attr_1>)f(=)i(<value_1>)479 613
y([,)g(...)f([,)h(<name_of_attr_k>)e(=)i(<value_k>]])360
672 y(WHERE)f(<condition>;)270 798 y Fn(Example)13 b(1.17)25
b Ft(T)l(o)15 b(change)g(the)f(v)o(alue)h(of)f(attrib)o(ute)g(PRICE)h
(of)f(the)g(part)h('Scre)o(w')e(in)h(the)h(relation)270
858 y(P)-5 b(AR)m(T)13 b(we)g(use:)360 962 y Fr(UPDATE)29
b(PART)360 1022 y(SET)g(PRICE)h(=)f(15)360 1081 y(WHERE)g(PNAME)g(=)h
('Screw';)270 1184 y Ft(The)13 b(ne)o(w)f(v)o(alue)g(of)g(attrib)o(ute)
g(PRICE)g(of)g(the)h(tuple)f(whose)g(name)h(is)f('Scre)o(w')f(is)i(no)o
(w)f(15.)270 1323 y Fn(Delete)270 1418 y Ft(T)l(o)h(delete)f(a)g(tuple)
g(from)f(a)h(particular)f(table)h(use)h(the)f(command)g(DELETE)i(FR)n
(OM.)f(The)g(syntax)f(is:)360 1522 y Fr(DELETE)29 b(FROM)g
(<table_name>)360 1582 y(WHERE)g(<condition>;)270 1708
y Fn(Example)13 b(1.18)25 b Ft(T)l(o)13 b(delete)g(the)g(supplier)f
(called)h('Smith')e(of)i(the)f(table)h(SUPPLIER)g(the)g(follo)o(wing)
270 1767 y(statement)f(is)h(used:)360 1871 y Fr(DELETE)29
b(FROM)g(SUPPLIER)360 1931 y(WHERE)g(SNAME)g(=)h('Smith';)270
2079 y Fh(1.3.4)59 b(System)15 b(Catalogs)270 2175 y
Ft(In)10 b(e)o(v)o(ery)g(SQL)g(database)h(system)f Fp(system)h
(catalogs)f Ft(are)g(used)g(to)g(keep)g(track)g(of)g(which)g(tables,)h
(vie)o(ws)270 2235 y(inde)o(x)o(es)16 b(etc.)24 b(are)15
b(de\002ned)g(in)g(the)g(database.)24 b(These)17 b(system)e(catalogs)h
(can)f(be)g(queried)g(as)g(if)g(the)o(y)270 2294 y(were)g(normal)g
(relations.)23 b(F)o(or)15 b(e)o(xample)h(there)e(is)i(one)f(catalog)g
(used)h(for)e(the)i(de\002nition)e(of)h(vie)o(ws.)270
2354 y(This)h(catalog)f(stores)h(the)f(query)g(from)f(the)h(vie)o(w)g
(de\002nition.)23 b(Whene)o(v)o(er)16 b(a)f(query)g(against)g(a)g(vie)o
(w)270 2414 y(is)f(made,)h(the)e(system)i(\002rst)e(gets)h(the)g
Fp(vie)o(w-de\002nition-query)f Ft(out)h(of)f(the)h(catalog)g(and)f
(materializes)270 2474 y(the)e(vie)o(w)g(before)g(proceeding)g(with)g
(the)g(user)g(query)g(\(see)h(section)f(3.4.1)h Fp(T)-5
b(ec)o(hniques)12 b(T)-5 b(o)12 b(Implement)270 2533
y(V)l(ie)o(ws)k Ft(for)e(a)h(more)f(detailed)g(description\).)21
b(F)o(or)14 b(more)g(information)f(about)i Fp(system)g(catalogs)f
Ft(refer)270 2593 y(to)e([D)n(A)-6 b(TE96)q(].)270 2742
y Fh(1.3.5)59 b(Embedded)15 b(SQL)270 2837 y Ft(In)h(this)h(section)g
(we)g(will)g(sketch)f(ho)o(w)h(SQL)g(can)g(be)g(embedded)f(into)h(a)g
(host)g(language)f(\(e.g.)i(C\).)270 2897 y(There)13
b(are)f(two)g(main)g(reasons)g(why)g(we)h(want)f(to)g(use)h(SQL)f(from)
g(a)g(host)h(language:)345 3000 y Fo(\017)25 b Ft(There)13
b(are)g(queries)f(that)h(cannot)g(be)g(formulated)e(using)i(pure)g(SQL)
g(\(i.e.)18 b(recursi)o(v)o(e)12 b(queries\).)395 3059
y(T)l(o)f(be)g(able)g(to)g(perform)e(such)j(queries)f(we)g(need)g(a)g
(host)g(language)g(with)g(a)g(greater)f(e)o(xpressi)o(v)o(e)395
3119 y(po)o(wer)h(than)h(SQL.)345 3223 y Fo(\017)25 b
Ft(W)l(e)11 b(simply)f(want)g(to)h(access)h(a)f(database)h(from)d(some)
i(application)g(that)f(is)h(written)g(in)f(the)h(host)395
3283 y(language)g(\(e.g.)h(a)g(ticket)e(reserv)o(ation)h(system)h(with)
f(a)h(graphical)f(user)g(interface)g(is)h(written)e(in)395
3342 y(C)h(and)g(the)g(information)f(about)g(which)h(tickets)g(are)g
(still)g(left)g(is)g(stored)g(in)g(a)g(database)h(that)f(can)395
3402 y(be)h(accessed)i(using)e(embedded)g(SQL\).)p eop
%%Page: 25 25
25 24 bop 198 60 a Fm(1.3.)29 b(THE)13 b(SQL)f(LANGU)n(A)n(GE)1160
b Ft(25)198 234 y(A)19 b(program)f(using)h(embedded)g(SQL)h(in)f(a)g
(host)h(language)f(consists)h(of)e(statements)i(of)f(the)g(host)198
294 y(language)c(and)g(of)g(embedded)g(SQL)g(\(ESQL\))g(statements.)25
b(Ev)o(ery)15 b(ESQL)h(statement)f(be)o(gins)g(with)198
354 y(the)d(ke)o(ywords)g(EXEC)h(SQL.)g(The)g(ESQL)g(statements)g(are)f
(transformed)g(to)g(statements)h(of)f(the)g(host)198
413 y(language)j(by)g(a)g Fp(pr)n(ecompiler)h Ft(\(mostly)e(calls)h(to)
g(library)f(routines)g(that)h(perform)f(the)g(v)o(arious)h(SQL)198
473 y(commands\).)273 533 y(When)i(we)g(look)f(at)h(the)g(e)o(xamples)g
(throughout)f(section)h(1.3.1)h(we)f(realize)f(that)h(the)g(result)g
(of)198 593 y(the)e(queries)g(is)g(v)o(ery)g(often)g(a)g(set)g(of)g
(tuples.)24 b(Most)15 b(host)g(languages)h(are)f(not)f(designed)i(to)e
(operate)198 653 y(on)h(sets)g(so)g(we)g(need)g(a)g(mechanism)g(to)g
(access)h(e)o(v)o(ery)e(single)h(tuple)g(of)f(the)h(set)g(of)f(tuples)h
(returned)198 712 y(by)h(a)g(SELECT)i(statement.)27 b(This)16
b(mechanism)g(can)g(be)h(pro)o(vided)e(by)h(declaring)f(a)i
Fp(cursor)p Ft(.)27 b(After)198 772 y(that)11 b(we)g(can)g(use)g(the)g
(FETCH)g(command)g(to)g(retrie)o(v)o(e)f(a)h(tuple)f(and)h(set)g(the)g
(cursor)g(to)f(the)h(ne)o(xt)g(tuple.)198 892 y(F)o(or)h(a)g(detailed)h
(discussion)g(on)f(embedded)g(SQL)h(refer)e(to)h([D)n(A)-6
b(TE96)q(],)12 b([D)n(A)-6 b(TE94)q(])12 b(or)g([ULL88].)p
eop
%%Page: 26 26
26 25 bop 270 609 a Fj(Chapter)26 b(2)270 858 y Fq(P)n(ostgr)n(eSQL)k
(fr)n(om)g(the)g(User')-5 b(s)32 b(P)n(oint)270 1008
y(of)f(V)-5 b(iew)270 1268 y Ft(This)13 b(chapter)f(contains)g
(information)f(that)h(will)f(be)i(useful)f(for)f(people)h(that)g(only)g
(want)g(to)g(use)h(Post-)270 1327 y(greSQL.)g(It)f(gi)o(v)o(es)h(a)g
(listing)f(and)h(description)f(of)g(the)g(a)o(v)o(ailable)h(features)f
(including)g(a)h(lot)f(of)g(e)o(xam-)270 1387 y(ples.)k(The)11
b(users)h(interested)f(in)g(the)g(internals)g(of)g(PostgreSQL)f(should)
h(read)g(chapter)g(3)g Fp(P)l(ostgr)n(eSQL)270 1447 y(fr)n(om)h(the)h
(Pr)n(ogr)o(ammer')n(s)g(P)l(oint)f(of)h(V)l(ie)o(w)p
Ft(.)270 1620 y Fi(2.1)71 b(A)18 b(Short)f(History)g(of)h(P)o(ostgr)o
(eSQL)270 1732 y Ft(PostgreSQL)c(is)h(an)g(enhancement)f(of)g(the)h
(POSTGRES)f(database)i(management)e(system,)i(a)e(ne)o(xt-)270
1792 y(generation)f(relational)g(DBMS)h(research)g(prototype)f(running)
g(on)g(almost)h(an)o(y)g(UNIX)g(based)g(oper)o(-)270
1852 y(ating)f(system.)20 b(The)14 b(original)e(POSTGRES)i(code,)g
(from)f(which)g(PostgreSQL)g(is)h(deri)o(v)o(ed,)g(was)f(the)270
1912 y(ef)o(fort)f(of)i(man)o(y)g(graduate)g(students,)h(under)o
(graduate)e(students,)i(and)f(staf)o(f)g(programmers)e(working)270
1971 y(under)d(the)h(direction)f(of)h(Professor)f(Michael)h
(Stonebraker)e(at)i(the)f(Uni)o(v)o(ersity)h(of)f(California,)h(Berke-)
270 2031 y(le)o(y)m(.)16 b(Originally)11 b(POSTGRES)i(implemented)e
(its)i(o)o(wn)f(query)g(language)g(called)g(POSTQUEL.)345
2092 y(In)18 b(1995)g(Andre)o(w)g(Y)-6 b(u)19 b(and)f(Jolly)h(Chen)g
(adapted)f(the)h(last)f(of)o(\002cial)g(release)h(of)f(POSTGRES)270
2152 y(\(v)o(ersion)d(4.2\))h(to)f(meet)h(their)f(o)o(wn)g
(requirements)g(and)g(made)h(some)g(major)e(changes)j(to)e(the)g(code.)
270 2211 y(The)i(most)g(important)e(change)i(is)f(the)h(replacement)f
(of)g(POSTQUEL)h(by)f(an)h(e)o(xtended)f(subset)i(of)270
2271 y(SQL92.)f(The)c(name)g(was)g(changed)f(to)h(Postgres95)f(and)h
(since)g(that)g(time)f(man)o(y)h(other)f(people)h(ha)o(v)o(e)270
2331 y(contrib)o(uted)h(to)h(the)g(porting,)g(testing,)h(deb)o(ugging)f
(and)g(enhancement)g(of)g(the)g(code.)24 b(In)14 b(late)h(1996)270
2391 y(the)d(name)h(was)f(changed)h(again)f(to)g(the)g(ne)o(w)g(of)o
(\002cial)g(name)g(PostgreSQL.)270 2563 y Fi(2.2)71 b(An)18
b(Ov)o(er)o(view)f(on)h(the)g(F)n(eatur)o(es)e(of)i(P)o(ostgr)o(eSQL)
270 2676 y Ft(As)d(mentioned)f(earlier)g(PostgreSQL)h(is)g(a)g
(relational)f(database)h(management)f(system)h(\(RDBMS\))270
2736 y(b)o(ut)h(in)f(contrast)h(to)f(the)h(most)g(traditional)f(RDBMSs)
h(it)g(is)g(designed)g(to)f(pro)o(vide)h(more)f(\003e)o(xibility)270
2796 y(to)j(the)f(user)m(.)33 b(One)18 b(e)o(xample)g(for)f(the)h
(impro)o(v)o(ed)f(\003e)o(xibility)g(is)h(the)g(support)f(for)g
Fp(user)i(de\002ned)f Ft(or)270 2855 y Fp(abstr)o(act)11
b(data)f(types)h Ft(\(ADTs\).)k(Another)10 b(e)o(xample)h(is)f(the)h
(support)f(of)g(user)g(de\002ned)h(SQL)f(functions.)270
2915 y(\(W)l(e)j(will)g(discuss)h(these)f(features)g(later)g(in)g
(section)g(2.5)h Fp(Some)f(of)g(P)l(ostgr)n(eSQL)n(')n(s)h(Special)e(F)
l(eatur)n(es)270 2975 y(in)g(Detail)p Ft(\))270 3095
y(Here)g(is)h(a)f(list)h(of)f(the)g(features)g(PostgreSQL)g(pro)o
(vides:)345 3197 y Fo(\017)25 b Ft(An)12 b(e)o(xtended)g(subset)h(of)f
(SQL92)h(as)g(query)f(language.)345 3299 y Fo(\017)25
b Ft(A)12 b(commandline)g(interface)f(called)h Fr(psql)g
Ft(using)h(GNU)f(readline.)345 3402 y Fo(\017)25 b Ft(A)12
b(client/serv)o(er)g(architecture)f(allo)o(wing)h(concurrent)f(access)j
(to)e(the)h(databases.)1145 3552 y(26)p eop
%%Page: 27 27
27 26 bop 198 60 a Fm(2.3.)29 b(WHERE)13 b(T)o(O)g(GET)g(POSTGRESQL)956
b Ft(27)273 234 y Fo(\017)25 b Ft(Support)11 b(for)g(btree,)i(hash)g
(or)e(rtree)h(inde)o(x)o(es.)273 331 y Fo(\017)25 b Ft(A)13
b(transaction)f(mechanism)h(based)h(on)f(the)g(two)f(phase)i(commit)e
(protocol)g(is)i(used)f(to)g(ensure)323 391 y(data)f(inte)o(grity)f
(throughout)h(concurrent)f(data)h(access.)273 488 y Fo(\017)25
b Ft(Host)17 b(based,)i(password,)f(crypt,)g(ident)e(\(RFC)h(1413\))f
(or)h(K)o(erberos)f(V4/V5)h(authentication)323 547 y(can)12
b(be)h(used)f(to)h(ensure)f(authorized)g(data)g(access.)273
644 y Fo(\017)25 b Ft(A)12 b(huge)g(amount)g(of)g(prede\002ned)g(data)g
(types.)273 741 y Fo(\017)25 b Ft(Support)11 b(for)g(user)i(de\002ned)f
(data)g(types.)273 838 y Fo(\017)25 b Ft(Support)11 b(for)g(user)i
(de\002ned)f(SQL)g(functions.)273 935 y Fo(\017)25 b
Ft(Support)11 b(for)g(reco)o(v)o(ery)h(after)g(a)h(crash.)273
1032 y Fo(\017)25 b Ft(A)12 b(precompiler)f(for)h(embedded)g(SQL)g(in)h
(C.)273 1129 y Fo(\017)25 b Ft(An)12 b(ODBC)h(interface.)273
1225 y Fo(\017)25 b Ft(A)12 b(JDBC)h(interface.)273 1322
y Fo(\017)25 b Ft(A)12 b(Tcl/Tk)h(interface.)273 1419
y Fo(\017)25 b Ft(A)12 b(Perl)g(interface.)198 1586 y
Fi(2.3)71 b(Wher)o(e)17 b(to)h(Get)f(P)o(ostgr)o(eSQL)198
1697 y Ft(PostgreSQL)26 b(is)h(a)o(v)o(ailable)f(as)i(source)e(distrib)
o(ution)g(\(v6.3.2)g(at)h(the)g(time)f(of)g(writing\))f(from)198
1757 y Fr(ftp://ftp.postgresql.org/pub/)p Ft(.)63 b(There)30
b(is)f(also)h(an)f(of)o(\002cial)f(homepage)h(for)198
1817 y(PostgreSQL)15 b(at)g Fr(http://www.postgresgl.org/)p
Ft(.)21 b(There)15 b(are)g(a)g(lot)g(of)g(hosts)g(mirroring)198
1877 y(the)d(contents)h(of)f(the)g(abo)o(v)o(e)h(mentioned)f(ones)h
(all)f(o)o(v)o(er)g(the)h(world.)198 2008 y Fn(Copyright)e(of)h(P)o
(ostgr)o(eSQL)198 2101 y Ft(PostgreSQL)17 b(is)h(not)f(public)g(domain)
g(software.)30 b(It)17 b(is)h(copyrighted)e(by)h(the)h(Uni)o(v)o
(ersity)e(of)h(Cali-)198 2161 y(fornia)e(b)o(ut)h(may)g(be)g(used)h
(according)f(to)g(the)g(licensing)g(terms)g(of)g(the)g(the)g(copyright)
e(included)i(in)198 2221 y(e)o(v)o(ery)h(distrib)o(ution)g(\(refer)f
(to)h(the)h(\002le)f Fr(COPYRIGHT)g Ft(included)g(in)g(e)o(v)o(ery)h
(distrib)o(ution)e(for)h(more)198 2281 y(information\).)198
2412 y Fn(Support)11 b(f)o(or)h(P)o(ostgr)o(eSQL)198
2506 y Ft(There)g(is)g(no)g(of)o(\002cial)e(support)i(for)f
(PostgreSQL.)g(That)h(means)h(there)e(is)h(no)g(obligation)e(for)h(an)o
(ybody)198 2565 y(to)h(pro)o(vide)g(maintenance,)h(support,)f(updates,)
h(enhancements)g(or)f(modi\002cations)g(to)g(the)g(code.)17
b(The)198 2625 y(whole)c(PostgreSQL)g(project)g(is)h(maintained)e
(through)h(v)o(olunteer)f(ef)o(fort)g(only)m(.)18 b(Ho)o(we)o(v)o(er)13
b(there)g(are)198 2685 y(man)o(y)f(mailing)g(lists)h(which)f(can)h(be)f
(subscribed)h(to)f(in)g(case)h(of)f(problems:)198 2804
y(Support)f(Mailing)h(Lists:)273 2864 y Fr(announce@postgreSQL.org)e
Ft(for)h(announcements.)273 2924 y Fr(ports@postgreSQL.org)f
Ft(for)h(OS-speci\002c)h(b)o(ugs.)273 2984 y Fr(bugs@postgreSQL.org)e
Ft(for)i(other)f(unsolv)o(ed)i(b)o(ugs.)273 3044 y Fr
(questions@postgreSQL.org)c Ft(for)j(general)g(discussion.)198
3163 y(Mailing)g(Lists)i(for)d(De)o(v)o(elopers:)273
3223 y Fr(hackers@postgreSQL.org)f Ft(for)h(serv)o(er)i(internals)f
(discussion.)273 3283 y Fr(docs@postgreSQL.org)e Ft(for)i(the)g
(documentation)f(project.)273 3342 y Fr(patches@postgreSQL.org)f
Ft(for)h(patches)i(and)f(discussion.)273 3402 y Fr
(mirrors@postgreSQL.org)e Ft(for)h(mirror)g(site)i(announcements.)p
eop
%%Page: 28 28
28 27 bop 270 60 a Ft(28)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Ft(T)l(o)i(subscribe)h(to)f(the)g(mailing)f(list)h
Fr(questions@postgreSQL.org)d Ft(for)i(e)o(xample)i(just)f(send)270
294 y(an)e(email)h(to)f Fr(questions-request@postgreSQL.o)o(rg)e
Ft(with)i(the)g(lines)360 401 y Fr(subscribe)360 461
y(end)270 567 y Ft(in)g(the)h(body)f(\(not)f(the)i(subject)f(line\).)
270 746 y Fi(2.4)71 b(Ho)o(w)18 b(to)g(use)f(P)o(ostgr)o(eSQL)270
861 y Ft(Before)11 b(we)h(can)g(use)g(PostgreSQL)g(we)g(ha)o(v)o(e)g
(to)f(get)h(and)g(install)f(it.)16 b(W)l(e)c(won')o(t)e(talk)i(about)g
(installing)270 921 y(PostgreSQL)g(here)h(because)g(the)g(installation)
f(procedure)g(is)h(straight)g(forward)e(and)i(described)f(v)o(ery)270
980 y(detailed)h(in)h(the)f(\002le)g Fr(INSTALL)g Ft(contained)g(in)g
(the)h(distrib)o(ution.)k(W)l(e)13 b(want)g(to)h(concentrate)f(on)g
(the)270 1040 y(basic)g(usage)g(of)f(PostgreSQL)g(after)f(a)i
(successful)g(setup)g(has)g(taken)e(place.)270 1194 y
Fh(2.4.1)59 b(Starting)14 b(The)h(P)o(ostmaster)270 1291
y Ft(As)j(mentioned)g(earlier)f(PostgreSQL)g(uses)i(a)f(traditional)f
(client/serv)o(er)h(architecture)f(to)h(pro)o(vide)270
1351 y(multi)c(user)g(access.)24 b(The)15 b(serv)o(er)g(is)g
(represented)f(by)g(a)h(program)e(called)i Fr(postmaster)e
Ft(which)i(is)270 1410 y(started)c(only)h(once)f(at)h(each)g(host.)j
(This)e(master)e(serv)o(er)h(process)g(listens)g(at)f(a)h(speci\002ed)g
(TCP/IP)f(port)270 1470 y(for)j(incoming)h(connections)g(by)g(a)h
(client.)24 b(F)o(or)15 b(e)o(v)o(ery)g(incoming)f(connection)h(the)g
Fr(postmaster)270 1530 y Ft(spa)o(wns)e(a)e(ne)o(w)h(serv)o(er)g
(process)g(\()p Fr(postgres)p Ft(\))e(and)h(continues)h(listening)f
(for)g(further)g(connections.)270 1590 y(Ev)o(ery)18
b(serv)o(er)f(process)g(spa)o(wned)h(in)f(this)h(way)f(handles)g(e)o
(xactly)g(one)h(connection)f(to)g(one)g(client.)270 1649
y(The)f Fr(postgres)e Ft(serv)o(er)i(processes)g(communicate)f(with)f
(each)i(other)f(using)g(UNIX)g(semaphores)270 1709 y(and)k(shared)h
(memory)e(to)i(ensure)f(data)h(inte)o(grity)e(throughout)g(concurrent)h
(data)g(access.)38 b(\(F)o(or)19 b(a)270 1769 y(more)d(detailed)g
(description)f(on)h(these)h(architectural)e(concepts)h(see)h(chapter)f
(3)g Fp(P)l(ostgr)n(eSQL)h(fr)n(om)270 1829 y(the)12
b(Pr)n(ogr)o(ammer')n(s)i(P)l(oint)e(of)g(V)l(ie)o(w)p
Ft(.\))270 1948 y(T)l(o)h(start)f(the)g(master)h(serv)o(er)f(process)h
(use)g(the)f(follo)o(wing)f(command:)330 2056 y Fr($)30
b(nohup)f(postmaster)g(>)g(server.log)g(2>&1)h(&)270
2161 y Ft(which)11 b(will)g(start)g Fr(postmaster)g Ft(in)g(the)g
(background)g(and)g(e)o(v)o(en)h(if)f(you)g(log)g(out)g(of)g(the)g
(system)h(the)270 2221 y(process)h(remains)f(acti)o(v)o(e.)k(All)c
(errors)g(and)g(messages)i(will)e(be)g(logged)g(to)g(the)h(\002le)f
Fr(server.log)p Ft(.)270 2341 y Fn(Note:)35 b Ft(The)23
b Fr(postmaster)e Ft(process)i(is)g(usually)g(started)f(by)g(a)h
(special)g Fp(database)g(superuser)270 2401 y Ft(called)c
Fr(postgres)f Ft(which)h(is)g(a)g(normal)g(UNIX)f(user)h(b)o(ut)g(has)g
(more)g(rights)f(concerning)h(Post-)270 2460 y(greSQL.)f(F)o(or)g
(security)g(reasons)h(it)f(is)g(strongly)g(recommended)f(not)h(to)g
(run)g(the)g Fr(postmaster)270 2520 y Ft(process)13 b(as)g(the)f
Fp(system)h(super)h(user)f Fr(root)p Ft(.)270 2674 y
Fh(2.4.2)59 b(Cr)o(eating)14 b(a)h(New)g(Database)270
2771 y Ft(Once)c(the)g Fr(postmaster)f Ft(daemon)g(is)i(running)e(we)h
(can)g(create)g(a)g(ne)o(w)f(database)i(using)f(the)g(follo)o(w-)270
2830 y(ing)h(command:)330 2938 y Fr($)30 b(createdb)f(testdb)270
3044 y Ft(which)22 b(will)g(create)g(a)g(database)h(called)f
Fr(testdb)p Ft(.)45 b(The)23 b(user)f(e)o(x)o(ecuting)h(the)f(command)f
(will)270 3103 y(become)12 b(the)f(database)h(administrator)f(and)g
(will)g(therefore)g(be)h(the)f(only)g(user)h(\(e)o(xcept)g(the)f
Fp(database)270 3163 y(superuser)j Fr(postgres)p Ft(\))d(who)h(can)h
(destroy)e(the)i(database)g(again.)270 3283 y Fn(Note:)35
b Ft(T)l(o)22 b(create)h(the)f(database)h(you)f(don')o(t)g(need)g(to)g
(kno)o(w)g(an)o(ything)g(about)g(the)g(tables)h(\(re-)270
3342 y(lations\))16 b(that)h(will)f(be)h(used)h(within)e(the)h
(database.)29 b(The)18 b(tables)f(will)f(be)h(de\002ned)g(later)f
(using)h(the)270 3402 y(SQL)c(statements)f(sho)o(wn)h(in)f(section)g
(2.4.4)h Fp(De\002ning)f(and)h(P)l(opulating)f(T)-5 b(ables)p
Ft(.)p eop
%%Page: 29 29
29 28 bop 198 60 a Fm(2.4.)29 b(HO)n(W)12 b(T)o(O)h(USE)g(POSTGRESQL)
1018 b Ft(29)198 234 y Fh(2.4.3)59 b(Connecting)15 b(T)-5
b(o)14 b(a)h(Database)198 335 y Ft(After)g(ha)o(ving)g(created)h(at)g
(least)g(one)g(database)g(we)g(can)g(make)g(our)f(\002rst)g(client)h
(connection)f(to)h(the)198 395 y(database)g(system)g(to)f(be)g(able)g
(to)g(de\002ne)g(tables,)i(populate)e(them,)h(retrie)o(v)o(e)f(data,)h
(update)f(data)g(etc.)198 455 y(Note)20 b(that)g(most)f(database)i
(manipulation)e(is)h(done)g(this)g(way)f(\(just)h(creating)f(and)h
(destroying)f(a)198 514 y(database)11 b(is)f(done)g(by)g(separate)h
(commands)f(which)g(are)g(in)g(fact)f(just)i(shell)f(scripts)g(also)h
(using)f Fr(psql)p Ft(\))198 634 y(The)j(connection)f(to)g(the)g(DBMS)h
(is)g(established)g(by)f(the)g(follo)o(wing)f(command:)258
749 y Fr($)30 b(psql)f(testdb)198 861 y Ft(which)18 b(will)f(make)g(a)h
(connection)g(to)f(a)h(database)g(called)g Fr(testdb)p
Ft(.)32 b Fr(psql)17 b Ft(is)h(a)g(command)f(line)198
920 y(interface)d(using)h(GNU)g(readline.)23 b(It)15
b(can)g(handle)g(a)g(connection)g(to)f(only)h(one)g(database)h(at)f(a)g
(time.)198 980 y(When)d(the)h(connection)f(is)g(established)h
Fr(psql)f Ft(presents)h(itself)f(as)h(follo)o(ws:)258
1095 y Fr(Welcome)29 b(to)h(the)f(POSTGRESQL)g(interactive)g(sql)g
(monitor:)318 1155 y(Please)g(read)g(the)h(file)f(COPYRIGHT)g(for)h
(copyright)f(terms)g(of)318 1215 y(POSTGRESQL)347 1334
y(type)h(\\?)g(for)f(help)h(on)f(slash)h(commands)347
1394 y(type)g(\\q)g(to)f(quit)347 1454 y(type)h(\\g)g(or)f(terminate)g
(with)h(semicolon)e(to)i(execute)f(query)288 1514 y(You)g(are)h
(currently)f(connected)g(to)g(the)h(database:)f(testdb)258
1633 y(testdb=>)198 1745 y Ft(No)o(w)16 b(you)g(can)g(either)g(enter)g
(an)o(y)g(v)o(alid)g(SQL)g(statement)h(terminated)e(by)h(a)g(';')i(or)d
(use)i(one)f(of)g(the)198 1805 y Fp(slash)d(commands)p
Ft(.)j(A)c(list)h(of)f(all)g(a)o(v)o(ailable)g Fp(slash)h(commands)f
Ft(can)h(be)f(obtained)g(by)h(typing)e Fr(')p Fo(n)p
Fr(?')p Ft(.)198 1924 y(Here)h(is)h(a)f(list)h(of)f(the)g(most)g
(important)g Fp(slash)h(commands)p Ft(:)273 2035 y Fo(\017)25
b(n)p Fr(?)f Ft(lists)13 b(all)f(a)o(v)o(ailable)g Fp(slash)h(commands)
g Ft(and)f(gi)o(v)o(es)h(a)f(short)g(description.)273
2151 y Fo(\017)25 b(n)p Fr(q)f Ft(quits)13 b Fr(psql)p
Ft(.)273 2266 y Fo(\017)25 b(n)p Fr(d)f Ft(lists)13 b(all)f(tables,)h
(vie)o(ws)g(and)f(inde)o(x)o(es)h(e)o(xisting)g(in)f(the)g(current)g
(database.)273 2381 y Fo(\017)25 b(n)p Fr(dt)f Ft(lists)13
b(only)f(tables.)273 2497 y Fo(\017)25 b(n)p Fr(dT)f
Ft(lists)13 b(all)f(a)o(v)o(ailable)g(data)h(types.)273
2612 y Fo(\017)25 b(n)p Fr(i)k Fk(<)p Fr(filename)p Fk(>)24
b Ft(reads)12 b(and)h(e)o(x)o(ecutes)g(the)f(queries)h(contained)f(in)g
Fr(filename)p Ft(.)273 2727 y Fo(\017)25 b(n)p Fr(l)f
Ft(lists)13 b(all)f(a)o(v)o(ailable)g(databases)i(kno)o(wn)d(to)i(the)f
(system.)273 2843 y Fo(\017)25 b(n)p Fr(connect)k Fk(<)p
Fr(database)p Fk(>)37 b Ft(terminates)19 b(the)g(current)g(connection)g
(and)g(opens)h(a)f(ne)o(w)323 2902 y(connection)12 b(to)g
Fr(database)p Ft(.)273 3018 y Fo(\017)25 b(n)p Fr(o)k
Fl([)p Fk(<)p Fr(filename)p Fk(>)p Fl(])23 b Ft(sends)14
b(all)e(query)g(output)f(to)i Fr(file)p Ft(.)198 3182
y Fh(2.4.4)59 b(De\002ning)15 b(and)g(P)o(opulating)f(T)-5
b(ables)198 3283 y Ft(De\002ning)13 b(tables)i(and)f(inserting)f
(tuples)h(is)g(done)g(by)g(the)g(SQL)g(statements)g Fr(CREATE)30
b(TABLE)13 b Ft(and)198 3342 y Fr(INSERT)29 b(INTO)p
Ft(.)14 b(F)o(or)f(a)g(detailed)h(description)e(on)i(the)f(syntax)h(of)
f(these)h(commands)f(refer)g(to)g(sec-)198 3402 y(tion)f(1.3.2)h
Fp(Data)f(De\002nition)p Ft(.)p eop
%%Page: 30 30
30 29 bop 270 60 a Ft(30)310 b Fm(CHAPTER)14 b(2.)25
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Fn(Example)h(2.1)25 b Ft(T)l(o)12 b(create)g(and)g(populate)g
(the)g(table)g(SUPPLIER)g(used)g(in)g(\002gure)g(1.1)g
Fp(The)g(suppliers)270 294 y(and)g(parts)h(database)f
Ft(we)h(could)f(use)h(the)f(follo)o(wing)f(session:)330
403 y Fr($)30 b(psql)f(testdb)330 522 y(Welcome)g(to)h(the)f
(POSTGRESQL)g(interactive)g(sql)g(monitor:)390 582 y(Please)g(read)g
(the)h(file)f(COPYRIGHT)g(for)h(copyright)f(terms)g(of)390
642 y(POSTGRESQL)419 761 y(type)h(\\?)g(for)f(help)h(on)f(slash)h
(commands)419 821 y(type)g(\\q)g(to)f(quit)419 881 y(type)h(\\g)g(or)f
(terminate)g(with)h(semicolon)e(to)i(execute)f(query)360
941 y(You)g(are)h(currently)f(connected)g(to)g(the)h(database:)f
(testdb)330 1060 y(testdb=>)g(create)g(table)g(supplier)g(\(sno)h
(int4,)330 1120 y(testdb->)f(sname)g(varchar\(20\),)330
1180 y(testdb->)g(city)g(varchar\(20\)\);)330 1239 y(CREATE)330
1299 y(testdb=>)g(insert)g(into)g(supplier)g(\(sno,)h(sname,)f(city\))
330 1359 y(testdb->)g(values)g(\(1,'Smith','London'\);)330
1419 y(INSERT)g(26187)g(1)330 1479 y(testdb=>)g(insert)g(into)g
(supplier)g(\(sno,)h(sname,)f(city\))330 1538 y(testdb->)g(values)g
(\(2,'Jones','Paris'\);)330 1598 y(INSERT)g(26188)g(1)330
1658 y(testdb=>)g(insert)g(into)g(supplier)g(\(sno,)h(sname,)f(city\))
330 1718 y(testdb->)g(values)g(\(3,'Adams','Vienna'\);)330
1777 y(INSERT)g(26189)g(1)330 1837 y(testdb=>)g(insert)g(into)g
(supplier)g(\(sno,)h(sname,)f(city\))330 1897 y(testdb->)g(values)g
(\(4,'Blake','Rome'\);)330 1957 y(INSERT)g(26190)g(1)330
2017 y(testdb=>)270 2123 y Ft(If)12 b(you)g(\002rst)g(put)g(all)g(the)h
(abo)o(v)o(e)f(commands)h(into)f(a)g(\002le)g(you)h(can)f(easily)h(e)o
(x)o(ecute)g(the)f(statements)h(by)270 2183 y(the)f Fp(slash)h(command)
25 b Fo(n)p Fr(i)k Fk(<)p Fr(file)p Fk(>)p Ft(.)270 2302
y(Note:)34 b(The)22 b(data)g(type)f Fr(int4)h Ft(is)g(not)f(part)g(of)h
(the)f(SQL92)h(standard.)44 b(It)21 b(is)h(a)g(b)o(uilt)f(in)h(Post-)
270 2362 y(greSQL)13 b(type)g(denoting)g(a)g(four)f(byte)h(signed)g
(inte)o(ger)m(.)18 b(F)o(or)13 b(information)f(on)h(which)g(data)g
(types)g(are)270 2422 y(a)o(v)o(ailable)g(you)h(can)g(use)g(the)f
Fo(n)p Fr(dT)h Ft(command)f(which)h(will)f(gi)o(v)o(e)g(a)h(list)g(and)
f(short)h(description)f(of)g(all)270 2482 y(datatypes)g(currently)e
(kno)o(wn)h(to)g(PostgreSQL.)270 2637 y Fh(2.4.5)59 b(Retrie)o(ving)13
b(Data)i(Fr)o(om)f(The)g(Database)270 2734 y Ft(After)19
b(ha)o(ving)g(de\002ned)h(and)f(populated)h(the)f(tables)h(in)g(the)g
(database)g Fr(testdb)f Ft(we)h(are)f(able)h(to)270 2794
y(retrie)o(v)o(e)10 b(data)h(by)g(formulating)e(queries)i(using)g
Fr(psql)p Ft(.)k(Ev)o(ery)d(query)e(has)h(to)g(be)g(terminated)f(by)h
(a)h(';'.)270 2927 y Fn(Example)h(2.2)25 b Ft(W)l(e)f(assume)h(that)f
(all)g(the)g(tables)g(form)f(\002gure)g(1.1)i Fp(The)e(suppliers)i(and)
f(parts)270 2987 y(database)19 b Ft(e)o(xist)h(in)f(the)g(database)g
Fr(testdb)p Ft(.)36 b(If)18 b(we)i(want)e(to)h(kno)o(w)g(all)g(parts)g
(that)g(are)g(sold)g(in)270 3047 y(London)12 b(we)h(use)g(the)f(follo)o
(wing)f(session:)330 3155 y Fr(testdb=>)29 b(select)g(p.pname)330
3215 y(testdb->)g(from)g(supplier)g(s,)h(sells)f(se,)h(part)f(p)330
3275 y(testdb->)g(where)g(s.sno=se.sno)g(and)330 3335
y(testdb->)208 b(p.pno=se.pno)29 b(and)330 3395 y(testdb->)208
b(s.city='London';)p eop
%%Page: 31 31
31 30 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(31)258 234 y Fr(pname)258 294 y(-----)258 354 y(Screw)258
413 y(Nut)258 473 y(\(2)29 b(rows\))258 593 y(testdb=>)198
729 y Fn(Example)13 b(2.3)25 b Ft(W)l(e)18 b(use)h(again)f(the)g
(tables)g(gi)o(v)o(en)g(in)g(\002gure)f(1.1.)33 b(No)o(w)18
b(we)g(want)g(to)g(retrie)o(v)o(e)f(all)198 789 y(suppliers)12
b(selling)h(no)f(parts)g(at)h(all)f(\(to)g(remo)o(v)o(e)g(them)g(from)f
(the)i(suppliers)f(table)g(for)g(e)o(xample\):)258 900
y Fr(testdb=>)29 b(select)g(*)h(from)f(supplier)g(s)258
960 y(testdb->)g(where)g(not)h(exists)258 1020 y(testdb->)507
b(\(select)29 b(sno)h(from)f(sells)g(se)258 1080 y(testdb->)537
b(where)29 b(se.sno)g(=)h(s.sno\);)258 1139 y(sno|sname|city)258
1199 y(---+-----+----)258 1259 y(\(0)f(rows\))258 1378
y(testdb=>)198 1487 y Ft(The)15 b(result)f(relation)g(is)h(empty)f(in)h
(our)f(e)o(xample)h(telling)f(us)h(that)f(e)o(v)o(ery)g(supplier)g
(contained)h(in)f(the)198 1546 y(database)e(sells)f(at)g(least)h(one)f
(part.)k(Note)c(that)g(we)g(used)g(a)h(nested)f(subselect)h(to)f
(formulate)e(the)i(query)m(.)198 1730 y Fi(2.5)71 b(Some)18
b(of)f(P)o(ostgr)o(eSQL)-8 b(')m(s)16 b(Special)i(F)n(eatur)o(es)e(in)i
(Detail)198 1847 y Ft(T)n(raditional)23 b(relational)g(database)h
(management)g(systems)g(\(RDMSs\))g(pro)o(vide)f(only)g(v)o(ery)h(fe)o
(w)198 1907 y(datatypes)16 b(including)e(\003oating)h(point)g(numbers,)
h(inte)o(gers,)g(character)f(strings,)i(mone)o(y)m(,)f(and)f(dates.)198
1967 y(This)j(makes)f(the)g(implementation)f(of)h(man)o(y)g
(applications)g(v)o(ery)g(dif)o(\002cult)e(and)j(that')m(s)f(why)g
(Post-)198 2026 y(greSQL)12 b(of)o(fers)e(substantial)i(additional)f
(po)o(wer)h(by)f(incorporating)f(the)i(follo)o(wing)f(additional)g
(basic)198 2086 y(concepts)i(in)f(such)h(a)f(way)g(that)g(users)h(can)g
(easily)f(e)o(xtend)h(the)f(system:)273 2194 y Fo(\017)25
b Ft(inheritance)273 2305 y Fo(\017)g Ft(user)12 b(de\002ned)g
(functions)273 2416 y Fo(\017)25 b Ft(user)12 b(de\002ned)g(types)273
2527 y Fo(\017)25 b Ft(rules)198 2636 y(Some)11 b(other)g(features,)h
(implemented)e(in)h(most)h(modern)e(RDBMSs)j(pro)o(vide)e(additional)f
(po)o(wer)h(and)198 2695 y(\003e)o(xibility:)273 2804
y Fo(\017)25 b Ft(constraints)12 b(\(gi)o(v)o(en)g(in)g(the)g
Fr(create)29 b(table)12 b Ft(command\))273 2915 y Fo(\017)25
b Ft(triggers)273 3026 y Fo(\017)g Ft(transaction)12
b(inte)o(grity)198 3184 y Fh(2.5.1)59 b(Inheritance)198
3283 y Ft(Inheritance)14 b(is)h(a)g(feature)f(well)g(kno)o(wn)g(from)g
(object)h(oriented)f(programming)e(languages)j(such)h(as)198
3342 y(Smalltalk)c(or)g(C++.)18 b(PostgreSQL)13 b(refers)f(to)h(tables)
g(as)g Fp(classes)h Ft(and)f(the)g(de\002nition)f(of)h(a)g
Fp(class)g Ft(may)198 3402 y(inherit)f(the)g(contents)g(of)g(another)g
Fp(class)p Ft(:)p eop
%%Page: 32 32
32 31 bop 270 60 a Ft(32)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Fn(Example)h(2.4)25 b Ft(First)12 b(we)g(de\002ne)g(a)h(table)f
(\(class\))h Fr(city)p Ft(:)330 320 y Fr(testdb=>)29
b(create)g(table)g(city)h(\()330 380 y(testdb->)f(name)g
(varchar\(20\),)330 440 y(testdb->)g(population)g(int4,)330
500 y(testdb->)g(altitude)g(int4\);)330 560 y(CREATE)330
619 y(testdb=>)270 706 y Ft(No)o(w)17 b(we)g(de\002ne)f(a)i(ne)o(w)e
(table)h(\(class\))g Fr(capital)f Ft(that)h(inherits)f(all)h(attrib)o
(utes)g(from)f Fr(city)g Ft(and)270 765 y(adds)d(a)f(ne)o(w)h(attrib)o
(ute)e Fr(country)h Ft(storing)g(the)g(country)f(which)i(it)f(is)g(the)
h(capital)f(of.)330 852 y Fr(testdb=>)29 b(create)g(table)g(capital)g
(\()330 912 y(testdb->)g(country)g(varchar\(20\))330
971 y(testdb->)g(\))h(inherits)f(\(city\);)330 1031 y(CREATE)330
1091 y(testdb=>)270 1177 y Fn(Note)p Ft(:)23 b(The)17
b(class)g Fr(capital)f Ft(inherits)g(only)g(the)g(attrib)o(utes)g(of)g
Fr(city)g Ft(\(not)g(the)g(tuples)h(stored)f(in)270 1237
y Fr(city)p Ft(\).)f(The)e(ne)o(w)f(table)g(can)h(be)g(used)f(as)h(if)f
(it)g(were)g(de\002ned)h(without)e(using)i(inheritance:)330
1323 y Fr(testdb=>)29 b(insert)g(into)g(capital)h(\(name,)f
(population,)330 1383 y(testdb->)656 b(altitude,)29 b(state\))330
1443 y(testdb->)g(values)g(\('Vienna',)g(1500000,)g(200,)g
('Austria'\);)330 1503 y(INSERT)g(26191)g(1)330 1562
y(testdb=>)270 1649 y Ft(Let')m(s)18 b(assume)g(that)f(the)g(tables)h
Fr(city)f Ft(and)g Fr(capital)g Ft(ha)o(v)o(e)h(been)f(populated)g(in)g
(the)h(follo)o(wing)270 1709 y(way:)330 1795 y Fr(city)179
b(name)149 b(|)29 b(population)g(|)h(altitude)629 1855
y(---------+------------+------)o(---)629 1914 y(Linz)149
b(|)g(200000)29 b(|)179 b(270)629 1974 y(Graz)149 b(|)g(250000)29
b(|)179 b(350)629 2034 y(Villach)59 b(|)179 b(50000)29
b(|)179 b(500)629 2094 y(Salzburg)29 b(|)149 b(150000)29
b(|)179 b(420)330 2273 y(capital)89 b(name)149 b(|)29
b(population)g(|)h(altitude)f(|)60 b(country)629 2333
y(---------+------------+------)o(----+----)o(-----)629
2393 y(Vienna)89 b(|)119 b(1500000)29 b(|)179 b(200)30
b(|)60 b(Austria)270 2479 y Ft(Standard)12 b(SQL92)g(queries)g(against)
h(the)f(abo)o(v)o(e)h(tables)f(beha)o(v)o(e)h(e)o(xactly)g(as)g(e)o
(xpected:)330 2565 y Fr(testdb=>)29 b(select)g(*)h(from)f(city)330
2625 y(testdb->)g(where)g(altitude)g(>)h(400;)330 2685
y(name)149 b(|)30 b(population)e(|)i(altitude)330 2745
y(---------+------------+-------)o(--)330 2804 y(Villach)59
b(|)179 b(50000)29 b(|)180 b(500)330 2864 y(Salzburg)29
b(|)149 b(150000)29 b(|)180 b(420)330 2924 y(\(2)29 b(rows\))330
3044 y(testdb=>)g(select)g(*)h(from)f(capital;)330 3103
y(name)149 b(|)30 b(population)e(|)i(altitude)f(|)60
b(country)330 3163 y(---------+------------+-------)o(---+-----)o(----)
330 3223 y(Vienna)89 b(|)119 b(1500000)29 b(|)180 b(200)29
b(|)60 b(Austria)330 3283 y(\(1)29 b(row\))330 3402 y(testdb=>)p
eop
%%Page: 33 33
33 32 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(33)198 234 y(If)11 b(we)g(want)g(to)g(kno)o(w)g(the)g(names)h(of)f
(all)g(cities)h(\(including)e(capitals\))h(that)g(are)g(located)h(at)f
(an)h(altitude)198 294 y(o)o(v)o(er)g(100)h(meters)f(the)g(query)g(is:)
258 376 y Fr(testdb=>)29 b(select)g(*)h(from)f(city*)258
436 y(testdb->)g(where)g(altitude)g(>)h(100;)258 495
y(name)149 b(|)30 b(population)e(|)i(altitude)258 555
y(---------+------------+-------)o(--)258 615 y(Linz)149
b(|)g(200000)29 b(|)180 b(270)258 675 y(Graz)149 b(|)g(250000)29
b(|)180 b(350)258 734 y(Villach)59 b(|)179 b(50000)29
b(|)180 b(500)258 794 y(Salzburg)29 b(|)149 b(150000)29
b(|)180 b(420)258 854 y(Vienna)89 b(|)119 b(1500000)29
b(|)180 b(200)258 914 y(\(5)29 b(rows\))258 1033 y(testdb=>)198
1115 y Ft(Here)14 b(the)h('*')f(after)g Fr(city)g Ft(indicates)h(that)f
(the)g(query)h(should)f(be)h(run)f(o)o(v)o(er)g Fr(city)h
Ft(and)f(all)h(classes)198 1175 y(belo)o(w)i Fr(city)g
Ft(in)g(the)g(inheritance)f(hierarchy)m(.)29 b(Man)o(y)18
b(of)e(the)i(commands)f(that)g(we)g(ha)o(v)o(e)g(already)198
1235 y(discussed)c(\(SELECT)l(,)i(UPD)n(A)-6 b(TE,)14
b(DELETE,)h(etc\))d(support)g(this)g('*')g(notation.)198
1373 y Fh(2.5.2)59 b(User)15 b(De\002ned)g(Functions)198
1467 y Ft(PostgreSQL)i(allo)o(ws)g(the)g(de\002nition)f(and)h(usage)h
(of)e Fp(user)i(de\002ned)f(functions)p Ft(.)30 b(The)17
b(ne)o(w)g(de\002ned)198 1527 y(functions)12 b(can)g(be)h(used)g
(within)e(e)o(v)o(ery)i(query)m(.)i(PostgreSQL)d(pro)o(vides)g(two)g
(types)g(of)g(functions:)273 1608 y Fo(\017)25 b Ft(Query)11
b(Language)i(\(SQL\))f(Functions:)j(functions)d(written)f(in)h(SQL.)273
1699 y Fo(\017)25 b Ft(Programming)14 b(Language)j(Functions:)22
b(functions)16 b(written)f(in)h(a)h Fp(compiled)f Ft(language)g(such)
323 1759 y(as)c(C.)198 1888 y Fn(Query)g(Language)g(\(SQL\))f
(Functions)198 1981 y Ft(These)k(functions)d(are)i(de\002ned)f(using)h
(SQL.)g(Note)f(that)g Fp(query)h(language)e(functions)h
Ft(do)h(not)f(e)o(xtend)198 2041 y(the)k Fp(e)o(xpr)n(essive)h(power)g
Ft(of)e(the)h(SQL92)g(standard.)29 b(Ev)o(ery)17 b Fp(query)g(language)
f(function)g Ft(can)h(be)g(re-)198 2100 y(placed)10 b(by)g(an)g
(appropriate)f(nested)h(query)f(\()p Fp(subselect)p Ft(\))h(without)f
(changing)h(the)f(semantical)h(meaning)198 2160 y(of)j(the)g(whole)g
(query)m(.)k(Ho)o(we)o(v)o(er)n(,)d(since)f(PostgreSQL)g(does)h(not)f
(allo)o(w)f Fp(subselects)j Ft(in)e(the)g Fp(selectlist)198
2220 y Ft(at)g(the)f(moment)g(b)o(ut)h(does)g(allo)o(w)f(the)g(usage)h
(of)g Fp(query)g(language)e(functions)p Ft(,)i(the)f
Fp(e)o(xpr)n(essive)i(power)198 2280 y Ft(of)e(PostgreSQL)-5
b(')m(s)13 b(current)e(SQL)i(implementation)e(is)i(e)o(xtended.)273
2340 y(The)44 b(de\002nition)f(of)h Fp(query)g(language)e(functions)i
Ft(is)g(done)g(using)g(the)g(command)198 2399 y Fr(create)29
b(function)g Fk(<)p Fr(function)p 958 2399 15 2 v 17
w(name)p Fk(>)o Ft(.)d(Ev)o(ery)16 b(function)f(can)h(take)f(zero)g(or)
h(more)f(ar)o(-)198 2459 y(guments.)23 b(The)16 b(type)f(of)f(e)o(v)o
(ery)h(ar)o(gument)f(is)h(speci\002ed)h(in)e(the)h(list)g(of)g(ar)o
(guments)f(in)h(the)g(function)198 2519 y(de\002nition.)28
b(The)17 b(type)f(of)h(the)f(function')m(s)g(result)h(is)f(gi)o(v)o(en)
h(after)f(the)g(ke)o(yword)g Fr(returns)g Ft(in)g(the)198
2579 y(function)d(de\002nition.)20 b(The)15 b(types)f(used)g(for)g(the)
g(ar)o(guments)f(and)h(the)g(return)g(v)o(alue)f(of)h(the)g(function)
198 2638 y(can)i(either)f(be)g Fp(base)h(types)g Ft(\(e.g.)25
b(int4,)17 b(v)o(archar)n(,)f(.)7 b(.)g(.)g(\))27 b(or)15
b Fp(composite)g(types)p Ft(.)26 b(\(F)o(or)15 b(each)g(class)i(\(ta-)
198 2698 y(ble\))c(that)g(is)h(created,)g(a)g(corresponding)f
Fp(composite)g(type)h Ft(is)g(de\002ned.)19 b Fr(supplier)12
b Ft(and)i Fr(part)f Ft(are)198 2758 y(e)o(xamples)g(for)e
Fp(composite)i(types)g Ft(after)e(the)i(tables)f Fr(supplier)g
Ft(and)g Fr(part)g Ft(ha)o(v)o(e)h(been)g(created.\))198
2864 y Fn(Example)g(2.5)25 b Ft(This)13 b(is)g(an)f(e)o(xample)g(using)
h(only)f Fp(base)h(types)p Ft(.)198 2984 y(Before)29
b(PostgreSQL)g(was)g(e)o(xtended)g(to)h(support)e(nested)i(subqueries)f
(user)h(de\002ned)f(query)198 3044 y(language)11 b(\(SQL\))f(functions)
h(could)g(be)g(used)g(to)g(simulate)g(them.)k(Consider)c(e)o(xample)h
(2.3)f(where)g(we)198 3103 y(ha)o(v)o(e)k(wanted)g(to)f(kno)o(w)h(the)f
(names)i(of)e(all)h(suppliers)f(that)h(do)g(not)f(sell)i(an)o(y)f(part)
f(at)h(all.)23 b(Normally)198 3163 y(we)13 b(would)f(formulate)g(the)h
(query)f(as)i(we)f(did)g(in)f(e)o(xample)i(2.3.)j(Here)c(we)g(want)g
(to)g(sho)o(w)g(a)g(possible)198 3223 y(way)h(of)g(formulating)f(the)h
(query)g(without)g(using)g(a)h(subquery)m(.)21 b(This)15
b(is)g(done)f(in)h(two)e(steps.)23 b(In)14 b(the)198
3283 y(\002rst)j(step)h(we)f(de\002ne)h(the)f(function)f
Fr(my)p 930 3283 V 18 w(exists)p Ft(.)30 b(In)17 b(the)h(second)g(step)
f(we)h(formulate)e(a)i(query)198 3342 y(using)12 b(the)h(ne)o(w)f
(function.)p eop
%%Page: 34 34
34 33 bop 270 60 a Ft(34)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Ft(In)f(the)h(\002rst)f(step)h(we)g(de\002ne)g(the)f(ne)o(w)h
(function)f Fr(my)p 1188 234 15 2 v 18 w(exists\(int4\))f
Ft(which)i(takes)f(an)h(inte)o(ger)g(as)270 294 y(ar)o(gument:)330
374 y Fr(testdb=>)29 b(create)g(function)g(my_exists\(int4\))f(returns)
h(int4)330 434 y(testdb->)g(as)g('select)h(count\(pno\))e(from)i(sells)
330 494 y(testdb->)148 b(where)30 b(sno)f(=)h($1;')f(language)g('sql';)
330 554 y(CREATE)330 613 y(testdb=>)270 694 y Ft(Here)12
b(is)h(the)f(second)h(step)g(which)f(performs)f(the)i(intended)f
(retrie)o(v)o(e:)330 774 y Fr(testdb=>)29 b(select)g(s.sname)g(from)h
(supplier)f(s)330 834 y(testdb->)g(where)g(my_exists\(s.sno\))f(=)i(0;)
330 894 y(sname)330 953 y(-----)330 1013 y(\(0)f(rows\))330
1133 y(testdb=>)270 1213 y Ft(No)o(w)12 b(let')m(s)h(ha)o(v)o(e)f(a)h
(look)f(at)g(what)h(is)f(happening)g(here.)k(The)d(function)e
Fr(my)p 1582 1213 V 18 w(exists\(int4\))g Ft(takes)270
1273 y(one)j(ar)o(gument)f(which)h(must)g(be)g(of)f(type)h(inte)o(ger)m
(.)20 b(W)n(ithin)13 b(the)h(function)f(de\002nition)g(this)h(ar)o
(gument)270 1332 y(can)20 b(be)f(refered)g(to)g(using)h(the)f($1)h
(notation)f(\(if)f(there)h(were)h(furhter)e(ar)o(guments)h(the)o(y)h
(could)f(be)270 1392 y(referred)13 b(to)i(by)f($2,)h($3,)h(.)7
b(.)g(.)g(\).)25 b Fr(my)p 889 1392 V 17 w(exists\(int4\))14
b Ft(returns)g(the)g(number)g(of)g(tuples)h(from)e(table)270
1452 y Fr(sells)19 b Ft(where)f(the)h(attrib)o(ute)f
Fr(sno)h Ft(is)h(equal)f(to)f(the)h(gi)o(v)o(en)g(ar)o(gument)g($1)f
(\()p Fr(sno)30 b(=)f($1)p Ft(\).)36 b(The)270 1512 y(ke)o(yword)12
b Fr(language)29 b('sql')13 b Ft(tells)h(PostgreSQL)f(that)h(the)f(ne)o
(w)h(function)e(is)i(a)g(query)f(language)270 1572 y(function.)345
1631 y(The)e(query)f(in)g(the)h(second)g(step)g(e)o(xamines)g(e)o(v)o
(ery)f(tuple)h(from)e(table)i Fr(supplier)f Ft(and)g(checks)i(if)270
1691 y(it)f(sati\002es)g(the)g(gi)o(v)o(en)g(quali\002cation.)j(It)d
(does)g(so)g(by)g(taking)g(the)f(supplier)h(id)g Fr(sno)f
Ft(of)h(e)o(v)o(ery)f(tuple)h(and)270 1751 y(gi)o(ving)g(it)i(as)f(an)h
(ar)o(gument)e(to)i(the)f(function)f Fr(my)p 1127 1751
V 18 w(exists\(int4\))p Ft(.)j(In)e(other)g(words)g(the)g(function)270
1811 y Fr(my)p 333 1811 V 18 w(exists\(int4\))17 b Ft(is)h(called)h
(once)f(for)g(e)o(v)o(ery)g(tuple)g(of)g(table)g Fr(supplier)p
Ft(.)33 b(The)19 b(function)270 1870 y(returns)10 b(the)h(number)f(of)h
(tuples)g(ha)o(ving)f(the)h(gi)o(v)o(en)f(supplier)h(id)g
Fr(sno)f Ft(contained)h(in)f(table)h Fr(sells)p Ft(.)k(A)270
1930 y(result)c(of)f(zero)h(means)h(that)f(no)g(such)g(tuple)g(is)g(a)o
(v)o(ailable)g(meaning)g(that)f(the)h(corresponding)g(supplier)270
1990 y(does)i(not)g(sell)g(a)g(single)g(part.)k(W)l(e)c(can)h(see)f
(that)g(this)g(query)f(is)i(semantically)e(equi)o(v)o(alent)g(to)h(the)
g(one)270 2050 y(gi)o(v)o(en)f(in)g(e)o(xample)h(2.3.)270
2155 y Fn(Example)g(2.6)25 b Ft(This)13 b(e)o(xample)f(sho)o(ws)h(ho)o
(w)f(to)g(use)h(a)g Fp(composite)f(type)h Ft(in)f(a)g(function)g
(de\002nition.)270 2274 y(Imagine)21 b(that)g(the)h(price)f(of)g(e)o(v)
o(ery)g(part)g(was)h(doubled)f(o)o(v)o(er)h(night.)42
b(If)21 b(you)h(want)e(to)i(look)f(at)270 2334 y(the)d(part)f(table)h
(with)f(the)h(ne)o(w)g(v)o(alues)f(you)h(could)g(use)g(the)g(follo)o
(wing)e(function)h(which)g(uses)i(the)270 2394 y Fp(composite)12
b(type)h Fr(part)f Ft(for)f(its)i(ar)o(gument:)330 2474
y Fr(testdb=>)29 b(create)g(function)g(new_price\(part\))f(returns)h
(float)330 2534 y(testdb->)g(as)g('select)h($1.price)f(*)g(2;')h
(language)f('sql';)330 2594 y(CREATE)330 2654 y(testdb=>)g(select)g
(pno,)g(pname,)h(new_price\(price\))e(as)h(new_price)330
2713 y(testdb->)g(from)g(part;)330 2773 y(pno)g(|)60
b(pname)f(|)h(new_price)330 2833 y(----+---------+-----------)360
2893 y(1)f(|)h(Screw)f(|)269 b(20)360 2952 y(2)59 b(|)h(Nut)119
b(|)269 b(16)360 3012 y(3)59 b(|)h(Bolt)89 b(|)269 b(30)360
3072 y(4)59 b(|)h(Cam)119 b(|)269 b(50)330 3132 y(\(4)29
b(rows\))330 3251 y(testdb=>)270 3332 y Ft(Note)12 b(that)h(this)g
(could)f(ha)o(v)o(e)h(been)g(done)f(by)g(a)h(normal)f(query)g
(\(without)g(using)g(a)h(user)g(de\002ned)f(func-)270
3391 y(tion\))g(as)g(well)h(b)o(ut)f(it')m(s)g(an)h(easy)g(to)f
(understand)g(e)o(xample)g(for)g(the)g(usage)h(of)f(functions.)p
eop
%%Page: 35 35
35 34 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(35)198 234 y Fn(Pr)o(ogramming)13 b(Language)f(Functions)198
328 y Ft(PostgreSQL)h(also)g(supports)g Fp(user)g(de\002ned)g
(functions)g Ft(written)f(in)h(C.)g(This)h(is)f(a)g(v)o(ery)g(po)o
(werful)f(fea-)198 387 y(ture)18 b(because)h(you)g(can)f(add)h(an)o(y)g
(function)e(that)i(can)f(be)h(formulated)e(in)i(C.)g(F)o(or)f(e)o
(xample)h(Post-)198 447 y(greSQL)c(lacks)h(the)f(function)f
Fr(sqrt\(\))g Ft(b)o(ut)h(it)g(can)h(be)f(easily)g(added)h(using)f(a)g
(programming)f(lan-)198 507 y(guage)e(function.)198 626
y Fn(Example)h(2.7)25 b Ft(W)l(e)18 b(sho)o(w)g(ho)o(w)g(to)g(realize)g
(the)g(user)g(de\002ned)g(function)f Fr(pg)p 1594 626
15 2 v 18 w(my)p 1672 626 V 18 w(sqrt\(int4\))p Ft(.)198
686 y(The)c(implementation)e(can)i(be)f(di)o(vided)g(into)g(three)g
(steps:)273 785 y Fo(\017)25 b Ft(formulating)10 b(the)j(ne)o(w)f
(function)f(in)h(C)273 885 y Fo(\017)25 b Ft(compiling)11
b(and)h(linking)g(it)g(to)g(a)h(shared)f(library)273
984 y Fo(\017)25 b Ft(making)11 b(the)i(ne)o(w)f(function)f(kno)o(wn)h
(to)g(PostgreSQL)198 1093 y Fn(F)o(ormulating)g(the)g(New)g(Function)f
(in)h(C:)25 b Ft(W)l(e)16 b(create)g(a)h(ne)o(w)e(\002le)h(called)g
Fr(sqrt.c)g Ft(and)g(add)g(the)323 1153 y(follo)o(wing)10
b(lines:)382 1272 y Fr(#include)29 b(<postgres.h>)382
1332 y(#include)g(<utils/palloc.h>)382 1392 y(#include)g(<math.h>)382
1511 y(int4)h(pg_my_sqrt\(int4)e(arg1\))382 1571 y({)442
1631 y(return)h(\(ceil\(sqrt\(arg1\)\)\);)382 1691 y(})323
1810 y Ft(The)17 b(function)g Fr(pg)p 664 1810 V 18 w(my)p
742 1810 V 17 w(sqrt\(\))g Ft(takes)h(one)f(ar)o(gument)g(of)g(type)g
Fr(int4)g Ft(which)g(is)h(a)g(Post-)323 1870 y(greSQL)i(type)g
(de\002ned)h(in)f Fr(postgres.h)f Ft(and)i(returns)f(the)h(inte)o(ger)f
(v)o(alue)g(ne)o(xt)h(to)f(the)323 1929 y(square)c(root)g(of)g(the)g
(ar)o(gument.)27 b(As)17 b(with)f Fp(query)h(language)d(functions)i
Ft(\(see)h(pre)o(vious)f(sec-)323 1989 y(tion\))c(the)h(ar)o(guments)g
(can)g(be)h(of)e Fp(base)i Ft(or)f(of)f Fp(composite)i(type)p
Ft(.)k(Special)13 b(care)g(must)g(be)h(taken)323 2049
y(when)d(using)g Fp(base)h(types)g Ft(that)f(are)h(lar)o(ger)e(than)i
(four)e(bytes)i(in)f(length.)k(PostgreSQL)c(supports)323
2109 y(three)h(types)g(of)g(passing)h(a)g(v)o(alue)f(to)g(the)g(user)h
(de\002ned)f(function:)382 2208 y Fo(\017)25 b Ft(pass)13
b(by)g(v)o(alue,)f(\002x)o(ed)h(length)382 2288 y Fo(\017)25
b Ft(pass)13 b(by)g(reference,)f(\002x)o(ed)g(length)382
2367 y Fo(\017)25 b Ft(pass)13 b(by)g(reference,)f(v)o(ariable)f
(length)323 2467 y(Only)k(data)h(types)g(that)g(are)g(1,)h(2)f(or)f(4)h
(bytes)g(in)g(length)g(can)g(be)g Fp(passed)g(by)g(value)p
Ft(.)27 b(W)l(e)16 b(just)323 2527 y(gi)o(v)o(e)d(an)g(e)o(xample)g
(for)g(the)g(usage)h(of)f Fp(base)g(types)h Ft(that)f(can)h(be)f(used)h
(for)e Fp(pass)i(by)g(value)f Ft(here.)323 2586 y(F)o(or)j(information)
g(on)h(ho)o(w)g(to)g(use)h(types)f(that)g(require)g Fp(pass)h(by)f(r)n
(efer)n(ence)i Ft(or)e(ho)o(w)g(to)g(use)323 2646 y Fp(composite)12
b(types)h Ft(refer)e(to)h([LOCK98].)198 2746 y Fn(Compiling)g(and)f
(Linking)h(It)g(to)g(a)h(Shar)o(ed)e(Library:)25 b Ft(PostgreSQL)14
b(binds)i(the)f(ne)o(w)g(function)f(to)323 2805 y(the)f(runtime)g
(system)i(by)f(using)g(a)g(shared)g(library)f(containing)g(the)h
(function.)20 b(Therefore)13 b(we)323 2865 y(ha)o(v)o(e)i(to)g(create)g
(a)g(shared)g(library)f(out)g(of)h(the)g(object\002le\(s\))f
(containing)g(the)h(function\(s\).)23 b(It)323 2925 y(depends)18
b(on)f(the)h(system)g(and)g(the)f(compiler)g(ho)o(w)h(this)f(can)h(be)g
(done.)32 b(On)18 b(a)g(Linux)f(ELF)323 2985 y(system)12
b(using)h Fr(gcc)f Ft(it)g(can)h(be)f(done)g(by)h(using)f(the)g(follo)o
(wing)f(commands:)382 3104 y Fr($)30 b(gcc)g(-I$PGROOT/include)e(-fpic)
h(-c)59 b(sqrt.c)30 b(-o)f(sqrt.o)382 3164 y($)h(gcc)g(-shared)f
(sqrt.o)g(-o)h(sqrt.so)323 3283 y Ft(where)17 b Fr($PGROOT)g
Ft(is)g(the)h(path)f(PostgreSQL)g(was)h(installed)f(to.)31
b(The)18 b(important)e(options)323 3342 y(gi)o(v)o(en)11
b(to)g Fr(gcc)g Ft(here)g(are)g Fr(-fpic)g Ft(in)g(the)g(\002rst)g
(line)g(which)g(tells)g Fr(gcc)g Ft(to)g(produce)g Fp(position)g(in-)
323 3402 y(dependent)e(code)h Ft(that)g(can)g(be)g(loaded)g(to)f(an)o
(y)h(address)h(of)e(the)h(process)g(image)g(and)g Fr(-shared)p
eop
%%Page: 36 36
36 35 bop 270 60 a Ft(36)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)395
234 y Ft(in)g(the)g(second)h(line)g(telling)f Fr(gcc)g
Ft(to)g(produce)h(a)f(shared)h(library)m(.)i(If)d(you)g(got)h(another)f
(system)395 294 y(where)k(the)g(abo)o(v)o(e)h(described)f(steps)h(do)f
(not)g(work)g(you)g(will)g(ha)o(v)o(e)g(to)h(refer)e(to)h(the)g(manual)
395 354 y(pages)i(of)g(your)g(c-compiler)f(\(often)g
Fr(man)30 b(cc)p Ft(\))18 b(and)g(your)f(linker)h(\()p
Fr(man)29 b(ld)p Ft(\))17 b(to)i(see)f(ho)o(w)395 413
y(shared)12 b(libraries)g(can)g(be)h(b)o(uilt.)270 599
y Fn(Making)f(the)f(New)i(Function)e(Known)g(to)h(P)o(ostgr)o(eSQL:)25
b Ft(No)o(w)f(we)g(ha)o(v)o(e)g(to)g(tell)f(PostgreSQL)395
659 y(about)18 b(the)g(ne)o(w)h(function.)34 b(W)l(e)18
b(do)h(so)g(by)f(using)h(the)g Fr(create)29 b(function)18
b Ft(command)395 719 y(within)11 b Fr(psql)h Ft(as)h(we)g(did)f(for)f
Fp(query)i(language)e(functions)p Ft(:)454 924 y Fr(testdb=>)29
b(create)h(function)f(pg_my_sqrt\(int4\))f(returns)h(int4)454
984 y(testdb->)g(as)h('/<where_ever_you_put_it>/sqrt.)o(so')454
1044 y(testdb->)f(language)g('c';)454 1103 y(CREATE)454
1163 y(testdb=>)395 1369 y Ft(From)13 b(no)o(w)h(on)g(the)g(function)f
Fr(pg)p 998 1369 15 2 v 18 w(my)p 1076 1369 V 17 w(sqrt\(int4\))h
Ft(can)g(be)g(used)h(in)f(e)o(v)o(ery)g(query)m(.)20
b(Here)395 1429 y(is)12 b(a)h(query)f(against)g(table)g
Fr(part)g Ft(using)h(the)f(ne)o(w)g(function:)454 1634
y Fr(testdb=>)29 b(select)h(pname,)f(price,)g(pg_my_sqrt\(price\))454
1694 y(testdb->)g(from)h(part)454 1754 y(testdb->)f(where)h
(pg_my_sqrt\(price\))e(<)h(10;)454 1813 y(pname)149 b
(|price|pg_my_sqrt)454 1873 y(----------+-----+----------)454
1933 y(Screw)g(|)60 b(10)30 b(|)239 b(4)454 1993 y(Nut)209
b(|)90 b(8)30 b(|)239 b(3)454 2053 y(Bolt)179 b(|)60
b(15)30 b(|)239 b(4)454 2112 y(Cam)209 b(|)60 b(25)30
b(|)239 b(5)454 2172 y(\(4)30 b(rows\))454 2292 y(testdb=>)270
2552 y Fh(2.5.3)59 b(User)15 b(De\002ned)g(T)l(ypes)270
2687 y Ft(Adding)10 b(a)g(ne)o(w)g(data)h(type)f(to)g(PostgreSQL)g
(also)h(requires)e(the)i(de\002nition)e(of)h(an)g Fp(input)g
Ft(and)g(an)h Fp(output)270 2746 y(function)p Ft(.)19
b(These)c(functions)e(are)g(implemented)g(using)h(the)f(techniques)h
(presented)g(in)f(the)h(pre)o(vious)270 2806 y(section)f
Fp(Pr)n(ogr)o(amming)f(Language)f(Functions)p Ft(.)16
b(The)d(functions)f(determine)f(ho)o(w)h(the)h(type)f(appears)270
2866 y(in)19 b(strings)g(\(for)f(input)h(by)g(the)g(user)g(and)g
(output)g(to)g(the)g(user\))g(and)g(ho)o(w)g(the)g(type)g(is)h(or)o
(ganized)270 2926 y(in)g(memory)m(.)36 b(The)20 b(input)g(function)f
(takes)g(a)h(null-delimited)e(character)h(string)h(as)g(its)g(input)f
(and)270 2986 y(returns)14 b(the)g(internal)g(\(in)f(memory\))g
(representation)h(of)g(the)g(type.)22 b(The)15 b(output)e(function)h
(takes)g(the)270 3045 y(internal)d(representation)g(of)g(the)g(type)h
(and)f(returns)g(a)h(null)f(delimited)g(character)g(string.)k(Besides)e
(the)270 3105 y(de\002nition)c(of)g Fp(input)h Ft(and)f
Fp(output)h(functions)f Ft(it)h(is)g(often)f(necessary)i(to)e(enhance)i
(operators)e(\(e.g.)16 b Fr('+')p Ft(\))270 3165 y(and)10
b(aggre)o(gate)g(functions)f(for)h(the)g(ne)o(w)g(data)g(type.)15
b(Ho)o(w)9 b(this)h(is)h(done)f(is)g(described)g(in)g(section)g(2.5.4)
270 3225 y Fp(Extending)i(Oper)o(ators)h Ft(and)g(section)f(2.5.5)h
Fp(Extending)g(Aggr)n(e)n(gates)p Ft(.)p eop
%%Page: 37 37
37 36 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(37)198 234 y Fn(Example)13 b(2.8)25 b Ft(Suppose)13
b(we)h(want)f(to)g(de\002ne)h(a)g(comple)o(x)f(type)g(which)h
(represents)f(comple)o(x)h(num-)198 294 y(bers.)i(Therefore)c(we)g
(create)h(a)f(ne)o(w)g(\002le)g(called)h Fr(complex.c)e
Ft(with)h(the)h(follo)o(wing)e(contents:)258 381 y Fr(#include)29
b(<postgres.h>)258 441 y(#include)g(<utils/palloc.h>)258
500 y(#include)g(<math.h>)258 620 y(/*)g(Type)h(definition)f(of)g
(Complex)g(*/)258 680 y(typedef)g(struct)g(Complex)g({)377
739 y(double)179 b(x;)377 799 y(double)g(y;)258 859 y(})30
b(Complex;)258 979 y(/*)f(Input)h(function:)f(takes)g(a)h(char)f
(string)g(of)h(the)g(from)288 1038 y(*)f('x,y')h(as)f(argument)g(where)
h(x)g(and)f(y)h(must)f(be)h(string)288 1098 y(*)f(representations)g(of)
g(double)h(numbers.)f(It)g(returns)g(a)288 1158 y(*)g(pointer)h(to)f
(an)h(instance)f(of)h(structure)e(Complex)i(that)288
1218 y(*)f(is)h(setup)f(with)h(the)f(given)h(x)g(and)f(y)h(values.)f
(*/)258 1277 y(Complex)g(*)258 1337 y(complex_in\(char)f(*str\))258
1397 y({)318 1457 y(double)h(x,)g(y;)318 1517 y(Complex)g(*result;)318
1636 y(/*)g(scan)h(the)f(input)h(string)f(and)g(set)h(x)g(and)f(y)h(to)
g(the)347 1696 y(*)g(corresponding)f(double)g(numbers)g(*/)318
1756 y(if)g(\(sscanf\(str,)g(")h(\()f(\045lf)h(,)g(\045lf)f(\)",)h(&x,)
f(&y\))h(!=)g(2\))f({)377 1815 y(elog\(ERROR,)g("complex_in:)g(error)g
(in)h(parsing"\);)377 1875 y(return)g(NULL;)318 1935
y(})318 1995 y(/*)f(reserve)g(memory)h(for)f(the)h(Complex)f(data)g
(structure)347 2055 y(*)h(Note:)g(we)f(use)h(palloc)f(here)g(because)h
(the)f(memory)347 2114 y(*)h(allocated)f(using)g(palloc)h(is)f(freed)h
(automatically)347 2174 y(*)g(by)g(PostgreSQL)f(when)g(it)h(is)f(not)h
(used)f(any)h(more)f(*/)318 2234 y(result)g(=)h(\(Complex)f
(*\)palloc\(sizeof\(Complex\)\);)318 2294 y(result->x)f(=)i(x;)318
2353 y(result->y)e(=)i(y;)318 2413 y(return)f(\(result\);)258
2473 y(})258 2593 y(/*)g(Output)h(Function)f(*/)258 2652
y(/*)g(Takes)h(a)g(pointer)f(to)g(an)h(instance)f(of)h(structure)f
(Complex)288 2712 y(*)g(as)h(argument)f(and)h(returns)f(a)h(character)e
(pointer)i(to)f(a)288 2772 y(*)g(string)h(representation)e(of)i(the)f
(given)h(argument)f(*/)258 2832 y(char)g(*)258 2891 y
(complex_out\(Complex)f(*complex\))258 2951 y({)318 3011
y(char)h(*result;)318 3131 y(if)g(\(complex)g(==)h(NULL\))f
(return\(NULL\);)318 3190 y(result)g(=)h(\(char)f(*\))h(palloc\(60\);)
318 3250 y(sprintf\(result,)e("\(\045g,\045g\)",)h(complex->x,)f
(complex->y\);)318 3310 y(return\(result\);)258 3370
y(})p eop
%%Page: 38 38
38 37 bop 270 60 a Ft(38)310 b Fm(CHAPTER)14 b(2.)25
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Ft(Note)h(that)g(the)g(functions)g(de\002ned)g(abo)o(v)o(e)h
(operate)f(on)g(types)g(that)g(require)g Fp(pass)g(by)h(r)n(efer)n
(ence)p Ft(.)20 b(The)270 294 y(functions)c(take)h(a)g(pointer)f(to)h
(the)g(data)g(as)h(ar)o(gument)e(and)h(return)f(a)i(pointer)e(to)h(the)
g(deri)o(v)o(ed)f(data)270 354 y(instead)h(of)g(passing)g(and)g
(returning)e(the)i(data)g(itself.)29 b(That')m(s)18 b(why)e(we)h(ha)o
(v)o(e)g(to)g(reserv)o(e)g(memory)270 413 y(using)f Fr(palloc)f
Ft(within)g(the)h(functions.)26 b(\(If)14 b(we)i(would)f(just)h
(de\002ne)f(a)h(local)g(v)o(ariable)f(and)h(return)270
473 y(the)e(addresses)h(of)f(these)h(v)o(ariables)f(the)g(system)h
(would)e(fail,)i(because)g(the)f(memory)f(used)i(by)f(local)270
533 y(v)o(ariables)e(is)h(freed)e(when)i(the)f(function)g(de\002ning)f
(these)i(v)o(ariables)f(completes.\))345 593 y(The)e(ne)o(xt)g(step)g
(is)g(to)g(compile)f(the)h(C-functions)f(and)h(create)f(the)h(shared)g
(library)f Fr(complex.so)p Ft(.)270 653 y(This)h(is)g(done)f(in)g(the)h
(way)f(described)g(in)h(the)f(pre)o(vious)g(section)g
Fp(Pr)n(ogr)o(amming)h(Language)e(Functions)270 712 y
Ft(and)j(depends)g(on)g(the)g(system)h(you)f(are)g(using.)k(On)c(a)g
(Linux)g(ELF)h(system)g(using)f Fr(gcc)f Ft(it)h(would)f(look)270
772 y(like)i(this:)330 868 y Fr($)30 b(gcc)f(-I$PGROOT/include)f(-fpic)
h(-c)60 b(complex.c)29 b(-o)h(complex.o)330 928 y($)g(gcc)f(-shared)g
(-o)h(complex.so)f(complex.o)270 1023 y Ft(No)o(w)11
b(we)h(are)f(ready)g(to)g(de\002ne)h(the)f(ne)o(w)g(datatype)g(b)o(ut)g
(before)g(that)g(we)h(ha)o(v)o(e)g(to)f(make)g(the)g
Fp(input)g Ft(and)270 1083 y Fp(output)h(function)g Ft(kno)o(wn)f(to)i
(PostgreSQL:)330 1179 y Fr(testdb=>)29 b(create)g(function)g
(complex_in\(opaque\))330 1238 y(testdb->)g(returns)g(complex)330
1298 y(testdb->)g(as)g('/<where_ever_you_put_it>/complex.so)o(')330
1358 y(testdb->)g(language)g('c';)330 1418 y(NOTICE:)59
b(ProcedureCreate:)28 b(type)h('complex')g(is)h(not)599
1477 y(yet)f(defined)330 1537 y(CREATE)330 1597 y(testdb=>)g(create)g
(function)g(complex_out\(opaque\))330 1657 y(testdb->)g(returns)g
(opaque)330 1717 y(testdb->)g(as)g
('/<where_ever_you_put_it>/complex.so)o(')330 1776 y(testdb->)g
(language)g('c';)330 1836 y(CREATE)330 1896 y(testdb=>)g(create)g(type)
g(complex)h(\()330 1956 y(testdb->)f(internallength)f(=)i(16,)330
2015 y(testdb->)f(input)g(=)h(complex_in,)330 2075 y(testdb->)f(output)
g(=)h(complex_out)330 2135 y(testdb->)f(\);)330 2195
y(CREATE)330 2255 y(testdb=>)270 2350 y Ft(Note)37 b(that)f(the)h(ar)o
(gument)f(type)h(gi)o(v)o(en)f(in)h(the)f(de\002nition)g(of)h
Fr(complex)p 1798 2350 15 2 v 17 w(out\(\))f Ft(and)270
2410 y Fr(complex)p 483 2410 V 17 w(in\(\))28 b Ft(-)g
Fr(opaque)f Ft(-)h(is)h(needed)f(by)g(PostgreSQL)g(to)g(be)g(able)g(to)
g(pro)o(vide)g(an)270 2470 y(uniform)14 b(mechanism)i(for)f(the)h
(de\002nition)e(of)i(the)f Fp(input)h Ft(and)f Fp(output)g(functions)h
Ft(needed)g(by)f(a)h(ne)o(w)270 2530 y(data)k(type.)40
b(It)20 b(is)h(not)f(necessary)h(to)f(specify)h(the)f(e)o(xact)h(type)f
(of)g(the)h(ar)o(guments)f(gi)o(v)o(en)g(to)g(the)270
2589 y(functions.)34 b(The)19 b Fp(input)f(function)g
Ft(is)h(ne)o(v)o(er)f(called)g(e)o(xplicitly)g(and)h(when)g(it)f(is)h
(called)f(implicitly)270 2649 y(\(e.g.)24 b(by)15 b(a)g(statement)h
(like)e Fr(insert)29 b(into)p Ft(\))15 b(it)f(is)i(clear)f(that)g(a)g
(character)g(string)f(\(i.e.)25 b(a)15 b(part)g(of)270
2709 y(the)h Fp(insert)h Ft(query\))e(will)g(be)i(passed)g(to)f(it.)26
b(The)17 b Fp(output)e(function)h Ft(is)g(only)g(called)g(\()g(by)g(an)
g(internal)270 2769 y(mechanism)h(of)g(PostgreSQL\))g(when)g(data)g(of)
g(the)g(corresponding)g(user)g(de\002ned)g(type)g(has)h(to)f(be)270
2828 y(displayed.)32 b(In)18 b(this)g(case)h(it)e(is)h(also)h(clear)e
(that)h(the)g(input)f(is)i(of)e(the)h(type)g(used)g(for)f(the)h
(internal)270 2888 y(representation)12 b(\(e.g.)k Fr(complex)p
Ft(\).)e(The)f(output)f(is)h(of)f(type)g(character)g(string.)270
3008 y(The)h(ne)o(w)f(type)g(can)h(no)o(w)f(be)g(used)h(as)g(if)f(it)g
(were)g(another)g(base)h(type:)330 3103 y Fr(testdb=>)29
b(create)g(table)g(complex_test)330 3163 y(testdb->)g(\(val)g
(complex\);)330 3223 y(CREATE)330 3283 y(testdb=>)g(insert)g(into)g
(complex_test)330 3342 y(testdb->)g(\(val\))g(values)g(\('\(1,2\)'\);)
330 3402 y(INSERT)59 b(155872)29 b(1)p eop
%%Page: 39 39
39 38 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(39)258 234 y Fr(testdb=>)29 b(insert)g(into)g(complex_test)258
294 y(testdb->)g(\(val\))g(values)g(\('\(3,4\)'\);)258
354 y(INSERT)59 b(155873)29 b(1)258 413 y(testdb=>)g(insert)g(into)g
(complex_test)258 473 y(testdb->)g(\(val\))g(values)g(\('\(5,6\)'\);)
258 533 y(INSERT)59 b(155874)29 b(1)258 653 y(testdb=>)g(select)g(*)h
(from)f(complex_test;)318 712 y(val)258 772 y(-----)258
832 y(\(1,2\))258 892 y(\(3,4\))258 951 y(\(5,6\))258
1011 y(\(3)g(rows\))258 1131 y(testdb=>)198 1272 y Fh(2.5.4)59
b(Extending)15 b(Operators)198 1365 y Ft(So)i(far)g(we)g(are)h(able)f
(to)h(de\002ne)f(a)h(ne)o(w)f(type,)i(create)f(tables)f(that)h(use)g
(the)f(ne)o(w)g(type)h(for)e(one)i(\(or)198 1425 y(more\))13
b(attrib)o(ute\(s\))g(and)g(populate)h(the)g(ne)o(w)g(tables)g(with)f
(data.)21 b(W)l(e)14 b(are)g(also)g(able)g(to)g(retrie)o(v)o(e)f(data)
198 1485 y(from)d(those)h(tables)h(as)g(long)e(as)i(we)f(do)g(not)g
(use)h(the)f(ne)o(w)g(data)g(types)h(within)e(the)h(quali\002cation)f
(of)h(the)198 1544 y(query)m(.)23 b(If)14 b(we)h(want)f(to)h(use)g(the)
g(ne)o(w)g(data)g(types)g(in)g(the)g Fr(where)f Ft(clause)i(we)f(ha)o
(v)o(e)g(to)g(adapt)g(some)198 1604 y(\(or)d(all\))f(of)h(the)h
(operators.)198 1718 y Fn(Example)g(2.9)25 b Ft(W)l(e)10
b(sho)o(w)h(ho)o(w)f(the)g(operator)g('=')g(can)g(be)h(adapted)f(for)g
(the)g(usage)h(on)f(the)h Fr(complex)198 1778 y Ft(data)17
b(type)g(de\002ned)g(in)f(section)i(2.5.3)f Fp(User)h(De\002ned)f(T)l
(ypes)p Ft(.)31 b(W)l(e)17 b(need)g(a)g(user)g(de\002ned)g(function)198
1838 y Fr(complex)p 411 1838 15 2 v 17 w(cmp\(complex,complex\))10
b Ft(that)j(returns)f Fr(true)g Ft(if)g(the)g(comple)o(x)g(numbers)g
(gi)o(v)o(en)198 1898 y(as)g(ar)o(guments)g(are)g(equal)f(and)h
Fr(false)g Ft(otherwise.)j(This)d(function)f(is)h(de\002ned)g(as)g
(described)g(in)g(sec-)198 1957 y(tion)h(2.5.2)i Fp(User)f(De\002ned)g
(Functions)p Ft(.)20 b(In)13 b(our)g(case)h(there)g(are)f(already)g
(two)g(functions)g(present)h(for)198 2017 y(the)f(usage)h(of)f(type)h
Fr(complex)e Ft(-the)h Fp(input)g Ft(and)h Fp(output)f(function)f
Ft(de\002ned)i(in)f(e)o(xample)g(2.8.)20 b(So)13 b(we)198
2077 y(can)k(add)f(the)h(ne)o(w)f(function)f Fr(complex)p
943 2077 V 18 w(cmp\(complex,complex\))f Ft(by)i(simply)g(appending)198
2137 y(the)c(follo)o(wing)f(lines)i(to)f(the)g(\002le)g
Fr(complex.c)g Ft(gi)o(v)o(en)g(in)g(e)o(xample)h(2.8:)258
2229 y Fr(/*)29 b(Comparison)g(Function)g(*/)258 2289
y(/*)g(returns)h(true)f(if)h(arg1)f(and)h(arg2)f(are)h(equal)f(*/)258
2348 y(bool)g(complex_cmp\(Complex)f(*arg1,)h(Complex)g(*arg2\))258
2408 y({)318 2468 y(if\(\(arg1->x)f(==)i(arg2->x\))f(&&)407
2528 y(\(arg1->y)g(==)h(arg2->y\)\))318 2588 y({)377
2647 y(return)g(true;)318 2707 y(})318 2767 y(else)318
2827 y({)377 2886 y(return)g(false;)318 2946 y(})258
3006 y(})198 3098 y Ft(No)o(w)12 b(we)h(create)f(the)g(shared)h
(library)e(again:)258 3190 y Fr($)30 b(gcc)f(-I$PGROOT/include)f(-fpic)
h(-c)60 b(complex.c)29 b(-o)h(complex.o)258 3250 y($)g(gcc)f(-shared)g
(-o)h(complex.so)f(complex.o)198 3342 y Ft(Note)10 b(that)f(all)h(the)f
(functions)h(de\002ned)f(in)h Fr(complex.c)e Ft(\()p
Fr(complex)p 1428 3342 V 17 w(in\(\),)29 b(complex)p
1834 3342 V 18 w(out\(\))198 3402 y Ft(and)12 b Fr(complex)p
495 3402 V 18 w(cmp\(\))p Ft(\))f(are)h(no)o(w)g(contained)g(in)h(the)f
(shared)g(library)g Fr(complex.so)p Ft(.)p eop
%%Page: 40 40
40 39 bop 270 60 a Ft(40)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Ft(No)o(w)k(we)h(make)g(the)f(ne)o(w)h(function)f(kno)o(wn)g(to)h
(PostgreSQL)f(and)h(after)f(that)h(we)g(de\002ne)f(the)h(ne)o(w)270
294 y(operator)11 b('=')h(for)g(the)g Fr(complex)g Ft(type:)330
394 y Fr(testdb=>)29 b(create)g(function)g
(complex_cmp\(complex,complex\))330 454 y(testdb->)g(returns)g(complex)
330 513 y(testdb->)g(as)g('/<where_ever_you_put_it>/complex.so)o(')330
573 y(testdb->)g(language)g('c';)330 633 y(CREATE)330
693 y(testdb=>)g(create)g(operator)g(=)h(\()330 753 y(testdb->)f
(leftarg)g(=)h(complex,)330 812 y(testdb->)f(rightarg)g(=)h(complex,)
330 872 y(testdb->)f(procedure)g(=)g(complex_cmp,)330
932 y(testdb->)g(commutator)g(=)g(=)330 992 y(testdb->)g(\);)330
1051 y(CREATE)330 1111 y(testdb=>)270 1211 y Ft(From)12
b(no)o(w)h(on)h(we)f(are)h(able)f(to)g(perform)f(comparisons)i(between)
f(comple)o(x)g(numbers)g(in)h(a)f(query')m(s)270 1271
y(quali\002cation)f(\(W)l(e)g(use)h(the)f(table)g Fr(complex)p
1100 1271 15 2 v 17 w(test)g Ft(as)h(de\002ned)f(in)h(e)o(xample)f
(2.8\):)330 1371 y Fr(testdb=>)29 b(select)g(*)h(from)f(complex_test)
330 1431 y(testdb->)g(where)g(val)h(=)f('\(1,2\)';)390
1491 y(val)330 1550 y(-----)330 1610 y(\(1,2\))330 1670
y(\(1)g(row\))330 1789 y(testdb=>)g(select)g(*)h(from)f(complex_test)
330 1849 y(testdb->)g(where)g(val)h(=)f('\(7,8\)';)390
1909 y(val)330 1969 y(-----)330 2029 y(\(0)g(rows\))330
2148 y(testdb=>)270 2291 y Fh(2.5.5)59 b(Extending)15
b(Aggr)o(egates)270 2385 y Ft(If)e(we)i(want)e(to)h(use)h(aggre)o(gate)
f(functions)f(on)h(attrib)o(utes)g(of)g(a)g(user)g(de\002ned)g(type,)h
(we)g(ha)o(v)o(e)f(to)g(add)270 2445 y(aggre)o(gate)19
b(functions)f(designed)h(to)g(work)f(on)h(the)g(ne)o(w)f(type.)36
b(Aggre)o(gates)19 b(in)g(PostgreSQL)f(are)270 2504 y(realized)12
b(using)h(three)f(functions:)345 2604 y Fo(\017)25 b
Fr(sfunc1)13 b Ft(\(state)i(function)e(one\):)19 b(is)c(called)g(for)e
(e)o(v)o(ery)i(tuple)f(of)g(the)g(current)g(group)g(and)g(the)395
2664 y(appropriate)d(attrib)o(ute')m(s)h(v)o(alue)h(of)f(the)h(current)
f(tuple)g(is)h(passed)h(to)e(the)h(function.)j(The)d(gi)o(v)o(en)395
2724 y(ar)o(gument)f(is)h(used)h(to)e(change)i(the)f(internal)f(state)h
(of)g(the)g(function)f(in)h(the)g(way)f(gi)o(v)o(en)h(by)g(the)395
2784 y(body)f(of)h(the)g(function.)k(F)o(or)c(e)o(xample)g
Fr(sfunc1)g Ft(of)g(the)g(aggre)o(gate)f(function)h Fr(sum)g
Ft(is)g(called)395 2843 y(for)f(e)o(v)o(ery)h(tuple)g(of)g(the)h
(current)e(group.)19 b(The)14 b(v)o(alue)f(of)g(the)g(attrib)o(ute)g
(the)g(sum)h(is)g(b)o(uilt)e(on)i(is)395 2903 y(taken)d(from)h(the)g
(current)g(tuple)g(and)g(added)g(to)h(the)f(internal)g(sum)g(state)h
(of)f Fr(sfunc1)p Ft(.)345 3003 y Fo(\017)25 b Fr(sfunc2)12
b Ft(is)h(also)g(called)g(for)g(e)o(v)o(ery)f(tuple)h(of)f(the)h(group)
g(b)o(ut)f(it)h(does)g(not)g(use)h(an)o(y)f(ar)o(gument)395
3063 y(from)g(outside)h(to)g(manipulate)g(its)h(state.)22
b(It)13 b(just)i(keeps)f(track)g(of)g(the)g(o)o(wn)g(internal)g(state.)
22 b(A)395 3123 y(typical)10 b(application)g(for)g Fr(sfunc2)h
Ft(is)g(a)g(counter)f(that)h(is)g(incremented)f(for)g(e)o(v)o(ery)h
(tuple)g(of)f(the)395 3183 y(group)h(that)h(has)h(been)g(processed.)345
3283 y Fo(\017)25 b Fr(finalfunc)14 b Ft(is)i(called)f(after)g(all)g
(tuples)g(of)g(the)g(current)g(group)f(ha)o(v)o(e)i(been)f(processed.)
26 b(It)395 3342 y(takes)10 b(the)f(internal)h(state)g(of)g
Fr(sfunc1)f Ft(and)h(the)g(state)h(of)e Fr(sfunc2)h Ft(as)g(ar)o
(guments)g(and)g(deri)o(v)o(es)395 3402 y(the)h(result)h(of)f(the)h
(aggre)o(gate)g(function)f(from)f(the)i(two)f(gi)o(v)o(en)h(ar)o
(guments.)j(F)o(or)d(e)o(xample)f(with)p eop
%%Page: 41 41
41 40 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(41)323 234 y(the)9 b(aggre)o(gate)h(function)f Fr(average)p
Ft(,)h Fr(sfunc1)f Ft(sums)h(up)g(the)f(attrib)o(ute)g(v)o(alues)h(of)f
(each)h(tuple)323 294 y(in)j(the)g(group,)g Fr(sfunc2)f
Ft(counts)i(the)f(tuples)g(in)g(the)g(group.)18 b Fr(finalfunc)12
b Ft(di)o(vides)h(the)g Fp(sum)323 354 y Ft(by)f(the)g
Fp(count)g Ft(to)g(deri)o(v)o(e)g(the)h(a)o(v)o(erage.)198
462 y(If)e(we)g(de\002ne)g(an)g(aggre)o(gate)g(using)h(only)f
Fr(sfunc1)f Ft(we)i(get)f(an)g(aggre)o(gate)g(that)g(computes)h(a)f
(running)198 522 y(function)h(of)h(the)g(attrib)o(ute)f(v)o(alues)h
(from)f(each)i(tuple.)j Fr(sum)c Ft(is)h(an)f(e)o(xample)g(for)f(this)h
(kind)g(of)g(aggre-)198 582 y(gate.)18 b(On)13 b(the)g(other)g(hand,)h
(if)e(we)h(create)h(an)f(aggre)o(gate)g(function)f(using)h(only)g
Fr(sfunc2)g Ft(we)g(get)g(an)198 642 y(aggre)o(gate)i(that)g(is)g
(independent)g(of)g(the)g(attrib)o(ute)f(v)o(alues)h(from)g(each)g
(tuple.)24 b Fr(count)15 b Ft(is)g(a)g(typical)198 702
y(e)o(xample)d(of)g(this)h(kind)f(of)g(aggre)o(gate.)198
840 y Fn(Example)h(2.10)25 b Ft(Here)h(we)g(want)g(to)g(realize)g(the)g
(aggre)o(gate)g(functions)g Fr(complex)p 1796 840 15
2 v 17 w(sum)g Ft(and)198 899 y Fr(complex)p 411 899
V 17 w(avg)12 b Ft(for)g(the)g(user)h(de\002ned)f(type)g
Fr(complex)g Ft(\(see)g(e)o(xample)h(2.8\).)198 1019
y(First)53 b(we)h(ha)o(v)o(e)g(to)f(create)g(the)h(user)f(de\002ned)h
(functions)f Fr(complex)p 1769 1019 V 17 w(add)g Ft(and)198
1079 y Fr(complex)p 411 1079 V 17 w(scalar)p 608 1079
V 17 w(div)p Ft(.)34 b(W)l(e)19 b(can)g(append)f(these)h(two)f
(functions)g(to)g(the)h(\002le)f Fr(complex.c)198 1138
y Ft(from)11 b(e)o(xample)i(2.8)f(again)h(\(as)f(we)h(did)f(with)g
Fr(complex)p 1214 1138 V 17 w(cmp)p Ft(\):)258 1250 y
Fr(/*)29 b(Add)h(Complex)f(numbers)g(*/)258 1310 y(Complex)g(*)258
1370 y(complex_add\(Complex)f(*arg1,)h(Complex)g(*arg2\))258
1430 y({)318 1489 y(Complex)g(*result;)318 1609 y(result)g(=)h
(\(Complex)f(*\)palloc\(sizeof\(Complex\)\);)318 1669
y(result->x)f(=)i(arg1->x)f(+)h(arg2->x;)318 1729 y(result->y)e(=)i
(arg1->y)f(+)h(arg2->y;)318 1788 y(return\(result\);)258
1848 y(})258 1968 y(/*)f(Final)h(function)f(for)g(complex)g(average)h
(*/)258 2027 y(/*)f(Transform)g(arg1)h(to)f(polar)h(coordinate)f(form)
288 2087 y(*)g(R)h(*)g(e\210\(j*phi\))f(and)g(divide)h(R)f(by)h(arg2.)
288 2147 y(*)f(Transform)g(the)h(new)f(result)h(back)f(to)h(cartesian)
288 2207 y(*)f(coordinates)g(*/)258 2267 y(Complex)g(*)258
2326 y(complex_scalar_div\(Complex)e(*sum,)i(int)h(count\))258
2386 y({)318 2446 y(Complex)f(*result;)318 2506 y(double)g(R,)g(phi;)
318 2625 y(result)g(=)h(\(Complex)f(*\)palloc\(sizeof\(Complex\)\);)318
2745 y(/*)g(transform)g(to)h(polar)f(coordinates)g(*/)318
2804 y(R)g(=)h(hypot\(sum->x,sum->y\);)318 2864 y(phi)f(=)h
(atan\(sum->y)f(/)g(sum->x\);)318 2984 y(/*)g(divide)g(by)h(the)g
(scalar)f(count)g(*/)318 3044 y(R)g(=)h(R)g(/)g(count;)318
3163 y(/*)f(transform)g(back)h(to)f(cartesian)g(coordinates)g(*/)318
3223 y(result->x)f(=)i(R)g(*)g(cos\(phi\);)318 3283 y(result->y)e(=)i
(R)g(*)g(sin\(phi\);)318 3342 y(return\(result\);)258
3402 y(})p eop
%%Page: 42 42
42 41 bop 270 60 a Ft(42)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Ft(Ne)o(xt)23 b(we)h(create)f(the)h(shared)f(library)f
Fr(complex.so)g Ft(again,)27 b(which)c(will)g(contain)g(all)g(func-)270
294 y(tions)16 b(de\002ned)g(in)h(the)f(pre)o(vious)g(e)o(xamples)g(as)
h(well)g(as)g(the)f(ne)o(w)g(functions)g Fr(complex)p
1878 294 15 2 v 17 w(add)g Ft(and)270 354 y Fr(complex)p
483 354 V 17 w(scalar)p 680 354 V 17 w(div)p Ft(:)330
538 y Fr($)30 b(gcc)f(-I$PGROOT/include)f(-fpic)h(-c)60
b(complex.c)29 b(-o)h(complex.o)330 598 y($)g(gcc)f(-shared)g(-o)h
(complex.so)f(complex.o)270 761 y Ft(No)o(w)13 b(we)g(ha)o(v)o(e)h(to)f
(make)g(the)g(functions)g(needed)g(by)h(the)f(ne)o(w)g(aggre)o(gates)g
(kno)o(wn)g(to)g(PostgreSQL.)270 821 y(After)f(that)g(we)h(de\002ne)g
(the)f(two)g(ne)o(w)h(aggre)o(gate)f(functions)g Fr(complex)p
1552 821 V 17 w(sum)h Ft(and)f Fr(complex)p 1966 821
V 17 w(avg)270 881 y Ft(that)g(make)g(use)h(of)f(the)g(functions)g
Fr(complex)p 1094 881 V 17 w(add)g Ft(and)h Fr(complex)p
1508 881 V 17 w(scalar)p 1705 881 V 17 w(div)p Ft(:)330
1066 y Fr(testdb=>)29 b(create)g(function)g
(complex_add\(complex,complex\))330 1125 y(testdb->)g(returns)g
(complex)330 1185 y(testdb->)g(as)g
('/<where_ever_you_put_it>/complex.so)o(')330 1245 y(testdb->)g
(language)g('c';)330 1305 y(CREATE)330 1365 y(testdb=>)g(create)g
(function)g(complex_scalar_div\(complex,int\))330 1424
y(testdb->)g(returns)g(complex)330 1484 y(testdb->)g(as)g
('/<where_ever_you_put_it>/complex.so)o(')330 1544 y(testdb->)g
(language)g('c';)330 1604 y(CREATE)330 1663 y(testdb=>)g(create)g
(aggregate)g(complex_sum)g(\()330 1723 y(testdb->)g(sfunc1)g(=)h
(complex_add,)330 1783 y(testdb->)f(basetype)g(=)h(complex,)330
1843 y(testdb->)f(stype1)g(=)h(complex,)330 1903 y(testdb->)f
(initcond1)g(=)g('\(0,0\)')330 1962 y(testdb->)g(\);)330
2022 y(CREATE)330 2082 y(testdb=>)g(create)g(aggregate)g(complex_avg)g
(\()330 2142 y(testdb->)g(sfunc1)g(=)h(complex_add,)330
2201 y(testdb->)f(basetype)g(=)h(complex,)330 2261 y(testdb->)f(stype1)
g(=)h(complex,)330 2321 y(testdb->)f(sfunc2)g(=)h(int4inc,)330
2381 y(testdb->)f(stype2)g(=)h(int4,)330 2441 y(testdb->)f(finalfunc)g
(=)g(complex_scalar_div,)330 2500 y(testdb->)g(initcond1)g(=)g
('\(0,0\)',)330 2560 y(testdb->)g(initcond2)g(=)g('0')330
2620 y(testdb->)g(\);)330 2680 y(CREATE)270 2843 y Ft(The)20
b(aggre)o(gate)e(function)g Fr(complex)p 976 2843 V 17
w(sum)h Ft(is)g(de\002ned)g(using)g(only)g Fr(sfunc1)p
Ft(.)35 b Fr(basetype)18 b Ft(is)270 2903 y(the)e(type)g(of)g(the)h
(result)f(of)g(the)g(aggre)o(gate)g(function.)27 b(The)17
b(function)e Fr(complex)p 1751 2903 V 17 w(add)h Ft(is)h(used)g(as)270
2963 y Fr(sfunc1)d Ft(and)h Fr(stype1)e Ft(de\002nes)i(the)g(type)f
Fr(sfunc1)g Ft(will)g(operate)g(on.)23 b Fr(initcond1)13
b Ft(gi)o(v)o(es)i(the)270 3022 y(initial)d(v)o(alue)g(of)g(the)g
(internal)g(state)g(of)g Fr(sfunc1)p Ft(.)270 3103 y(If)20
b(we)h(look)f(at)g(the)h(de\002nition)e(of)i(the)f(aggre)o(gate)g
(function)g Fr(complex)p 1618 3103 V 17 w(avg)h Ft(we)f(can)h(see)g
(that)270 3163 y(the)k(part)f(concerning)h Fr(sfunc1)f
Ft(is)i(identical)e(to)h(the)g(corresponding)f(part)h(of)f(the)h
(de\002nition)270 3223 y(of)e Fr(complex)p 548 3223 V
17 w(sum)p Ft(.)49 b(The)25 b(only)e(dif)o(ference)f(is)i(the)f
(additional)g(de\002nition)g(of)g Fr(sfunc2)g Ft(and)270
3283 y Fr(finalfunc)p Ft(.)34 b(The)19 b(b)o(uilt)f(in)g(function)g
Fr(int4inc)g Ft(is)h(used)g(as)g Fr(sfunc2)f Ft(and)h(increments)f(the)
270 3342 y(internal)c(state)i(of)e Fr(sfunc2)g Ft(for)h(e)o(v)o(ery)f
(tuple)h(processed.)24 b(After)14 b(all)h(tuples)g(ha)o(v)o(e)g(been)h
(processed)270 3402 y Fr(complex)p 483 3402 V 17 w(scalar)p
680 3402 V 17 w(div)d Ft(is)f(used)h(as)g Fr(finalfunc)e
Ft(to)i(create)f(the)g(a)o(v)o(erage.)p eop
%%Page: 43 43
43 42 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(43)198 234 y(From)11 b(no)o(w)h(on)h(we)f(can)h(use)g(the)f(ne)o
(w)g(aggre)o(gate)g(functions:)258 334 y Fr(testdb=>)29
b(select)g(*)h(from)f(complex_test;)318 394 y(val)258
454 y(-----)258 514 y(\(1,2\))258 573 y(\(3,4\))258 633
y(\(5,6\))258 693 y(\(3)g(rows\))258 813 y(testdb=>)g(select)g
(complex_sum\(val\))f(from)i(complex_test;)347 872 y(val)258
932 y(------)258 992 y(\(9,12\))258 1052 y(\(1)f(row\))258
1171 y(testdb=>)g(select)g(complex_avg\(val\))f(from)i(complex_test;)
318 1231 y(val)258 1291 y(-----)258 1351 y(\(3,4\))258
1410 y(\(1)f(row\))258 1530 y(testdb=>)198 1673 y Fh(2.5.6)59
b(T)l(riggers)198 1767 y Ft(PostgreSQL)14 b(supports)h(the)f(calling)g
(of)g(C)h(functions)f(as)h(trigger)f(actions.)22 b(T)n(riggers)15
b(are)g(not)f(a)h(fea-)198 1827 y(ture)d(that)h(is)g(only)f(present)h
(in)f(PostgreSQL.)h(In)f(fact)g(most)h(modern)f(RDMSs)h(support)g
(triggers.)j(W)l(e)198 1887 y(describe)g(them)g(here)g(because)i(the)e
(pre)o(vious)f(sections)i(are)g(necessary)g(to)f(understand)g(the)g
(imple-)198 1946 y(mentation)c(chosen.)273 2006 y(At)g(the)h(moment)f
(it)g(is)h(possible)g(to)f(de\002ne)h(trigger)e(actions)i(that)f(are)h
(e)o(x)o(ecuted)g Fp(befor)n(e)g Ft(and)g Fp(after)198
2066 y Ft(the)k(SQL)h(commands)f Fr(insert,)29 b(update)17
b Ft(or)g Fr(delete)g Ft(for)g(a)g(tuple.)31 b(T)n(riggers)18
b(can)f(be)h(used)198 2126 y(to)e(ensure)g(data)g(inte)o(grity)m(.)26
b(F)o(or)15 b(e)o(xample)h(we)h(can)f(de\002ne)g(a)g(trigger)f(action)h
(that)g(returns)f(an)h(error)198 2186 y(whene)o(v)o(er)11
b(somebody)g(wants)f(to)h(insert)g(\(or)f(update\))h(a)g(tuple)g(with)f
(a)h(ne)o(gati)o(v)o(e)g(supplier)g(id)g Fr(sno)f Ft(into)198
2245 y(table)i Fr(supplier)g Ft(de\002ned)g(in)g(\002gure)g(1.1.)273
2305 y(The)36 b(system)g(stores)h(information)d(about)h(when)h(a)g
(trigger)f(action)h(has)g(to)g(be)g(per)o(-)198 2365
y(formed.)75 b(Whene)o(v)o(er)33 b(a)g(command)f(triggering)f(an)i
(action)f(is)h(detected,)38 b(the)33 b Fr(trigger)198
2425 y(manager)g Ft(is)h(called)f(within)g(PostgreSQL,)h(which)f
(initializes)g(a)h(global)f(data)h(structure)198 2485
y Fr(TriggerData)29 b(*CurrentTriggerData)10 b Ft(and)i(calls)h(the)f
(appropriate)g(trigger)f(function.)198 2604 y(A)44 b(central)f(role)h
(in)f(the)h(de\002nition)f(of)h(trigger)e(functions)i(plays)g(the)g
(global)f(data)198 2664 y(structure)84 b Fr(TriggerData)29
b(*CurrentTriggerData)83 b Ft(\(The)h(global)h(pointer)198
2724 y Fr(CurrentTriggerData)10 b Ft(can)j(be)g(accessed)g(from)e
(within)h(e)o(v)o(ery)g(trigger)g(function\):)258 2824
y Fr(typedef)29 b(struct)g(TriggerData)258 2884 y({)318
2944 y(TriggerEvent)118 b(tg_event;)318 3003 y(Relation)238
b(tg_relation;)318 3063 y(HeapTuple)208 b(tg_trigtuple;)318
3123 y(HeapTuple)g(tg_newtuple;)318 3183 y(Trigger)268
b(*tg_trigger;)258 3242 y(})30 b(TriggerData;)198 3342
y Ft(No)o(w)12 b(we)g(gi)o(v)o(e)g(a)g(short)g(description)f(of)h(the)f
(structure')m(s)h(contents)g(rele)o(v)o(ant)f(for)g(the)h(e)o(xample)g
(belo)o(w)m(.)198 3402 y(F)o(or)g(a)g(detailed)h(description)e(of)h
(this)h(and)f(other)g(structures)g(and)h(functions)e(refer)h(to)g
([LOCK98]:)p eop
%%Page: 44 44
44 43 bop 270 60 a Ft(44)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)345
234 y Fo(\017)25 b Fr(tg)p 458 234 15 2 v 17 w(event)p
Ft(:)j(Describes)19 b(the)f(e)o(v)o(ent)h(the)f(function)g(is)h(called)
g(for)m(.)34 b(Contains)19 b(information)395 294 y(about)11
b(when)g(the)g(function)g(was)g(called)h(\()p Fp(befor)n(e)f
Ft(or)g Fp(after)23 b Ft(the)11 b(command)g(e)o(x)o(ecution\))h(and)f
(for)395 354 y(which)h(command)g(it)g(was)g(called)h(\()p
Fr(insert,)28 b(update)12 b Ft(or)g Fr(delete)p Ft(\).)345
450 y Fo(\017)25 b Fr(tg)p 458 450 V 17 w(relation)p
Ft(:)87 b(Is)49 b(a)g(pointer)e(to)i(a)g(structure)f(describing)g(the)g
(relation.)395 510 y Fr(tg)p 458 510 V 17 w(relation-)p
Fk(>)p Fr(rd)p 844 510 V 17 w(att)12 b Ft(is)g(of)g(special)h(interest)
f(for)g(us)h(because)g(it)f(can)g(be)h(gi)o(v)o(en)f(as)h(an)395
570 y(ar)o(gument)e(to)h(the)h(function)e Fr(SPI)p 990
570 V 18 w(getbinval\(\))g Ft(described)h(later)m(.)345
667 y Fo(\017)25 b Fr(tg)p 458 667 V 17 w(trigtuple)p
Ft(:)16 b(Is)e(a)f(pointer)g(to)g(the)g(tuple)g(for)g(which)g(the)g
(trigger)f(is)i(\002red.)k(If)12 b(the)i(com-)395 726
y(mand)e(is)g Fr(insert)g Ft(or)g Fr(delete)g Ft(this)g(is)h(the)f
(tuple)g(to)h(be)f(returned)f(by)i(the)f(trigger)f(function.)345
823 y Fo(\017)25 b Fr(tg)p 458 823 V 17 w(newtuple)p
Ft(:)18 b(If)c(the)g(command)g(is)g Fr(update)g Ft(this)g(is)g(a)h
(pointer)e(to)h(the)g(ne)o(w)g(v)o(ersion)h(of)395 883
y(tuple)d(and)g(NULL)h(otherwise.)i(This)e(is)g(what)f(has)h(to)f(be)g
(returned)g(by)g(the)g(trigger)f(function)h(if)395 942
y(the)g(command)g(is)g Fr(update)p Ft(.)270 1058 y Fn(Example)h(2.11)25
b Ft(W)l(e)16 b(de\002ne)g(a)h(trigger)e(function)g(called)i
Fr(trigf\(\))e Ft(that)h(is)h(designed)f(to)h(pre)o(v)o(ent)270
1117 y(inserting)12 b(\(updating\))f(tuples)h(with)g(a)h(ne)o(gati)o(v)
o(e)f(supplier)g(id)g Fr(sno)g Ft(into)g(table)h Fr(supplier)p
Ft(.)270 1237 y(First)26 b(we)g(ha)o(v)o(e)h(to)f(de\002ne)g(the)h
(function)e Fr(trigf\(\))h Ft(using)g(C)h(and)f(therefore)f(we)i
(create)f(a)270 1297 y(ne)o(w)14 b(\002le)g Fr(trigger.c)p
Ft(.)20 b(The)15 b(function)e(de\002nition)h(is)g(done)g(in)g(e)o
(xactly)h(the)f(same)g(way)g(as)h(for)e(the)270 1356
y(de\002nition)e(of)h(user)h(de\002ned)f(functions)g(\(see)g(section)h
(2.5.2\).)270 1476 y(Here)f(are)h(the)f(contents)g(of)g
Fr(trigger.c)p Ft(:)270 1570 y Fr(#include)29 b(<executor/spi.h>)270
1629 y(#include)g(<commands/trigger.h>)270 1749 y(HeapTuple)270
1809 y(trigf\(\))270 1868 y({)h(TupleDesc)208 b(tupdesc;)330
1928 y(HeapTuple)g(rettuple;)330 1988 y(bool)358 b(isnull;)330
2048 y(int)388 b(val;)330 2167 y(if)29 b(\(!CurrentTriggerData\))390
2227 y(elog\(ERROR,)f("trigf:)h(triggers)g(are)h(not)f(initialized"\);)
330 2347 y(/*)g(tuple)h(to)f(return)h(to)f(Executor)g(*/)330
2406 y(if)g(\(TRIGGER_FIRED_BY_UPDATE\(CurrentTrig)o(gerData->)o
(tg_event)o(\)\))390 2466 y(rettuple)g(=)g
(CurrentTriggerData->tg_newtuple;)330 2526 y(else)390
2586 y(rettuple)g(=)g(CurrentTriggerData->tg_trigtuple;)330
2705 y(tupdesc)g(=)h(CurrentTriggerData->tg_relati)o(on->rd_at)o(t;)330
2765 y(CurrentTriggerData)e(=)h(NULL;)330 2885 y(/*)g(get)h(the)g
(value)f(of)h(attribute)e(1)i(of)g(the)f(current)h(tuple)f(*/)330
2944 y(val)g(=)h(SPI_getbinval\(rettuple,)d(tupdesc,)i(1,)h(&isnull\);)
330 3064 y(/*)f(if)h(the)g(value)f(is)h(NULL)f(or)h(<)g(0)f(return)h
(an)f(error)h(*/)330 3124 y(if)f(\(isnull)h(||)f(val)h(<)g(0\))f({)419
3184 y(elog\(ERROR,"insert/update:)e(sno)j(must)f(be)h(a)g(value)f(>)h
(0"\);)330 3243 y(})330 3303 y(return)f(\(rettuple\);)270
3363 y(})p eop
%%Page: 45 45
45 44 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(45)198 234 y(The)20 b(function)e Fr(SPI)p 573 234
15 2 v 18 w(getbinval)g Ft(is)i(part)e(of)h(the)g Fp(Server)i(Pr)n(ogr)
o(amming)e(Interface)g(\(SPI\))f Ft(de-)198 294 y(scribed)13
b(in)g(section)g(2.5.7.)19 b(It)13 b(takes)g(the)g(current)f(tuple,)h
(the)g(description)g(of)g(the)g(relation,)g(the)g(num-)198
354 y(ber)k(of)g(the)h(attrib)o(ute)f(and)g(the)h(address)g(of)f(a)h(v)
o(ariable)f Fr(isnull)g Ft(as)h(ar)o(guments)f(and)h(returns)f(the)198
413 y(binary)c(v)o(alue)h(of)f(the)h(gi)o(v)o(en)f(attrib)o(ute)g(from)
g(the)h(current)f(tuple.)20 b(If)13 b(the)g(attrib)o(ute')m(s)h(v)o
(alue)f(is)h(NULL)198 473 y Fr(isnull)e Ft(is)g(set)h(to)f
Fr(true)g Ft(otherwise)h(to)f Fr(false)p Ft(.)273 533
y Fr(trigf\(\))23 b Ft(\002rst)g(checks)h(whether)f(it)h(was)f(called)h
(by)f(an)h Fr(update)f Ft(command)g(or)g(by)h(an)198
593 y Fr(insert)19 b Ft(and)g(sets)h Fr(rettuple)e Ft(accordingly)m(.)
36 b(Then)19 b(it)g(gets)h(the)f(v)o(alue)g(of)g(the)g(\002rst)g
(attrib)o(ute)198 653 y(of)e(the)g(current)g(tuple)g(\(remember)f
Fr(sno)i Ft(is)f(the)h(\002rst)f(attrib)o(ute)f(in)i(the)f(relation)g
Fr(supplier)p Ft(\).)30 b(If)198 712 y(the)14 b(v)o(alue)h(is)f
(greater)g(than)g(zero)h(the)f(current)g(tuple)g(is)h(returned)e(\(and)
h(inserted)h(or)f(updated)g(by)g(the)198 772 y(e)o(x)o(ecutor)e(of)f
(PostgreSQL\))g(otherwise)h(an)g(error)f(is)h(returned)f(\()p
Fr(elog\(ERROR,)p Fk(:)d(:)g(:)n Fr(\))k Ft(logs)g(an)g(error)198
832 y(and)g(aborts)h(processing\))f(and)g(the)g(table)h
Fr(supplier)e Ft(won')o(t)g(be)i(af)o(fected.)198 951
y(T)l(o)g(create)f(a)h(shared)f(library)f(out)i(of)f
Fr(trigger.c)f Ft(we)h(use)h(the)g(commands:)258 1035
y Fr($)30 b(gcc)f(-I$PGROOT/include)f(-I$PGSRC/include/)g(-fpic)h(\\)
258 1095 y(>)h(-c)f(trigger.c)g(-o)h(trigger.o)258 1155
y($)g(gcc)f(-shared)g(-o)h(trigger.so)f(trigger.o)198
1238 y Ft(Note)24 b(that)f(for)g(the)g(compilation)g(of)g(trigger)g
(functions)g(the)h(source)f(code)h(of)g(PostgreSQL)f(is)198
1298 y(necessary)m(.)16 b Fr($PGSRC)c Ft(points)g(to)h(the)f(place)g
(where)h(the)f(sources)h(are)f(installed.)198 1418 y(Ne)o(xt)20
b(we)h(ha)o(v)o(e)g(to)f(make)f(the)i(function)e Fr(trigf\(\))h
Ft(kno)o(wn)f(to)h(PostgreSQL)g(by)g(the)h Fr(create)198
1477 y(function)13 b Ft(command)h(in)f(the)h(same)h(way)e(we)h(did)g
(for)f(the)h(functions)g(in)f(the)h(pre)o(vious)g(e)o(xamples)198
1537 y(\(e.g.)19 b(e)o(xample)14 b(2.8\).)k(After)13
b(that)g(we)h(can)f(de\002ne)g(the)h(trigger)e Fr(tbefore)p
Ft(.)18 b(The)c(de\002nition)f(ensures)198 1597 y(that)e(function)g
Fr(trigf\(\))g Ft(gi)o(v)o(en)g(as)i(the)e(trigger)g(action)g(will)g
(be)h(e)o(x)o(ecuted)g Fr(before)f Ft(the)h(e)o(x)o(ecution)198
1657 y(of)24 b(the)g(commands)g Fr(insert)g Ft(and)g
Fr(update)g Ft(af)o(fecting)f(the)h(table)g Fr(supplier)p
Ft(.)51 b(Note)24 b(that)198 1717 y Fr(insert)17 b Ft(and)h
Fr(update)f Ft(commands)h(e)o(x)o(ecuted)g(against)g(tables)g(other)g
(than)f Fr(supplier)g Ft(won')o(t)198 1776 y(cause)c(the)f(e)o(x)o
(ecution)h(of)f(function)f Fr(trigf\(\))p Ft(.)258 1860
y Fr(testdb=>)29 b(create)g(function)g(trigf\(\))g(returns)g(opaque)258
1920 y(testdb->)g(as)g('/<where_ever_you_put_it/trigger.so')258
1980 y(testdb->)g(language)g('c';)258 2039 y(CREATE)258
2099 y(testdb=>)g(create)g(trigger)g(tbefore)258 2159
y(testdb->)g(before)g(insert)g(or)h(update)f(on)h(supplier)258
2219 y(testdb->)f(for)g(each)h(row)f(execute)g(procedure)g(trigf\(\);)
258 2278 y(CREATE)258 2338 y(testdb=>)198 2422 y Ft(No)o(w)14
b(we)g(can)g(check)g(if)g(the)g(trigger)f(is)h(working)f(correctly)m(.)
20 b(If)13 b(the)h(v)o(alue)g(for)f Fr(sno)g Ft(is)i(greater)e(than)198
2482 y(zero)f(the)h Fr(insert)e Ft(and)i Fr(update)e
Ft(commands)i(against)f(table)g Fr(supplier)g Ft(are)g(not)g(af)o
(fected.)258 2565 y Fr(testdb=>)29 b(insert)g(into)g(supplier)258
2625 y(testdb->)g(\(sno,)g(sname,)g(city\))258 2685 y(testdb->)g
(values\(5,)g('Miles',)g('Berlin'\);)258 2745 y(INSERT)g(156064)g(1)258
2864 y(testdb=>)g(insert)g(into)g(supplier)258 2924 y(testdb->)g
(\(sno,)g(sname,)g(city\))258 2984 y(testdb->)g(values\(-2,)g('Huber',)
g('Munich'\);)258 3044 y(ERROR:)59 b(insert/update:)28
b(sno)i(must)f(be)h(a)g(value)f(>)h(0)258 3163 y(testdb=>)f(update)g
(supplier)258 3223 y(testdb->)g(set)g(sno)h(=)g(-2)258
3283 y(testdb->)f(where)g(sname)g(=)h('Adams';)258 3342
y(ERROR:)59 b(insert/update:)28 b(sno)i(must)f(be)h(a)g(value)f(>)h(0)
258 3402 y(testdb=>)p eop
%%Page: 46 46
46 45 bop 270 60 a Ft(46)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Fh(2.5.7)59 b(Ser)o(v)o(er)14 b(Pr)o(ogramming)f(Interface)g
(\(SPI\))270 328 y Ft(The)20 b Fp(Server)g(Pr)n(ogr)o(amming)g
(Interface)f(\(SPI\))g Ft(gi)o(v)o(es)g(the)h(user)f(the)h(ability)e
(to)i(run)f(SQL)g(queries)270 387 y(from)10 b(inside)i(user)f
(de\002ned)h(functions.)j(SPI)10 b(is)i(just)f(a)h(set)g(of)f(nati)o(v)
o(e)g(interface)g(functions)g(to)g(simplify)270 447 y(the)29
b(access)h(to)f(the)g Fr(query)g(parser,)g(planner,)g(optimizer)f
Ft(and)h Fr(executor)g Ft(of)270 507 y(PostgreSQL)12
b(\(refer)f(to)h(chapter)g(3)h Fp(P)l(ostgr)n(eSQL)g(fr)n(om)f(the)g
(Pr)n(ogr)o(ammer')n(s)i(P)l(oint)e(of)g(V)l(ie)o(w)p
Ft(\).)270 626 y(The)h(set)g(of)f(functions)g(of)f(SPI)h(can)g(be)h(di)
o(vided)f(into)g(the)g(follo)o(wing)f(parts:)345 724
y Fo(\017)25 b Ft(Interface)11 b(Functions:)17 b(These)d(functions)e
(are)h(used)h(to)f(establish)h(a)f(connection)g(to)g(a)g(running)395
784 y(backend.)i(Whene)o(v)o(er)c(you)h(want)g(to)f(e)o(x)o(ecute)i(a)f
(SQL)g(query)g(within)f(a)h(user)g(de\002ned)g(function)395
844 y(you)g(will)g(ha)o(v)o(e)g(to)h(connect)f(to)g(a)h(backend)f(by)g
Fr(SPI)p 1314 844 15 2 v 18 w(connect\(\))p Ft(.)454
943 y Fn(\226)25 b Fr(SPI)p 597 943 V 18 w(connect\(\))11
b Ft(opens)i(a)f(connection)g(to)h(the)f(PostgreSQL)g(backend.)454
1022 y Fn(\226)25 b Fr(SPI)p 597 1022 V 18 w(finish\(\))11
b Ft(closes)i(a)g(connection)f(to)g(the)h(PostgreSQL)f(backend.)454
1101 y Fn(\226)25 b Fr(SPI)p 597 1101 V 18 w(exec\(\))15
b Ft(takes)g(a)h(character)f(string)h(containing)f(a)g(SQL)h(query)f
(and)h(a)g(number)504 1160 y Fr(tcount)11 b Ft(as)h(ar)o(guments)f(and)
g(e)o(x)o(ecutes)h(the)g(query)m(.)i(The)e(result)f(can)h(be)f
(obtained)g(from)504 1220 y(the)17 b(global)g(data)g(structure)f
Fr(SPI)p 1108 1220 V 18 w(tuptable)g Ft(which)h(is)g(set)h(by)f
Fr(SPI)p 1801 1220 V 18 w(exec\(\))p Ft(.)29 b(If)504
1280 y Fr(tcount)12 b Ft(is)i(zero)e(then)h(the)g(query)f(is)i(e)o(x)o
(ecuted)f(for)f(all)h(tuples)g(returned)f(by)h(the)g(query)504
1340 y(scan.)27 b(Using)16 b Fr(tcount)f Fk(>)h Ft(0)g(restricts)g(the)
f(number)h(of)f(tuples)h(for)f(which)h(the)g(query)504
1399 y(will)d(be)h(e)o(x)o(ecuted.)21 b(This)14 b(function)f(should)g
(only)h(be)g(called)f(after)g Fr(SPI)p 1786 1399 V 18
w(connect\(\))504 1459 y Ft(has)g(been)f(processed)h(and)g(a)f
(connection)g(has)h(been)g(established.)454 1538 y Fn(\226)25
b Fr(SPI)p 597 1538 V 18 w(prepare\(\))85 b Ft(creates)h(and)g(returns)
f(an)h(e)o(x)o(ecution)g(plan)504 1598 y(\(parser+planner+optimizer\))
23 b(b)o(ut)j(doesn')o(t)g(e)o(x)o(ecute)g(the)g(query)m(.)56
b(\(The)26 b(function)504 1658 y(performs)15 b(the)i(same)f(steps)h(as)
g Fr(SPI)p 1163 1658 V 18 w(exec\(\))f Ft(e)o(xcept)g(that)g(it)g(does)
h(not)f(e)o(x)o(ecute)h(the)504 1717 y(plan.)f(Should)11
b(only)h(be)h(called)f(after)g(a)h(connection)f(has)g(been)h
(established.)454 1796 y Fn(\226)25 b Fr(SPI)p 597 1796
V 18 w(saveplan\(\))10 b Ft(stores)h(a)g(plan)g(prepared)f(by)h
Fr(SPI)p 1518 1796 V 18 w(prepare\(\))f Ft(in)h(safe)g(mem-)504
1856 y(ory)h(protected)g(from)f(freeing)h(by)g Fr(SPI)p
1199 1856 V 17 w(finish\(\))p Ft(.)454 1935 y Fn(\226)25
b Fr(SPI)p 597 1935 V 18 w(execp\(\))12 b Ft(e)o(x)o(ecutes)h(a)g(plan)
f(prepared)g(by)g Fr(SPI)p 1491 1935 V 18 w(prepare\(\))g
Ft(or)g(returned)f(by)504 1995 y Fr(SPI)p 597 1995 V
18 w(saveplan\(\))p Ft(.)345 2094 y Fo(\017)25 b Ft(Interface)8
b(Support)i(Functions:)j(These)f(functions)e(can)g(be)h(used)g(from)e
(within)h(a)g(connected)h(or)395 2153 y(within)g(an)g(unconnected)h
(user)f(de\002ned)h(function.)j(An)c(e)o(xample)h(for)f(the)g(use)h
(from)f(within)g(an)395 2213 y(unconnected)k(function)g(was)h(gi)o(v)o
(en)g(in)f(e)o(xample)h(2.11)g(where)g Fr(SPI)p 1634
2213 V 17 w(getbinval\(\))f Ft(was)395 2273 y(used)h(to)g(deli)o(v)o
(er)g(the)g(v)o(alue)g(of)g(attrib)o(ute)g Fr(sno)g Ft(from)f(the)h(ne)
o(w)g(\(to)g(be)g(inserted\))g(tuple.)27 b(An)395 2333
y(e)o(xample)12 b(for)f(the)h(use)g(from)f(within)g(a)h(connected)g
(function)f(will)h(be)g(gi)o(v)o(en)g(in)f(e)o(xample)h(2.12.)454
2432 y Fn(\226)25 b Fr(SPI)p 597 2432 V 18 w(copytuple\(\))11
b Ft(makes)h(a)h(copy)f(of)f(the)i(tuple)f(gi)o(v)o(en)g(as)h(ar)o
(gument.)454 2510 y Fn(\226)25 b Fr(SPI)p 597 2510 V
18 w(modifytuple\(\))j Ft(modi\002es)i(one)g(or)f(more)h(attrib)o(utes)
f(of)h(a)g(gi)o(v)o(en)g(tu-)504 2570 y(ple.)73 b(The)32
b(ne)o(w)g(v)o(alues)f(for)g(the)g(attrib)o(utes)g(to)g(be)h(changed)g
(are)f(passed)h(to)504 2630 y Fr(SPI)p 597 2630 V 18
w(modifytuple\(\))11 b Ft(as)i(ar)o(guments.)454 2709
y Fn(\226)25 b Fr(SPI)p 597 2709 V 18 w(fnumber\(\))11
b Ft(takes)h(the)g(description)g(of)g(a)g(tuple)g(and)g(the)h
Fp(name)f Ft(of)g(an)g(attrib)o(ute)504 2769 y(as)h(ar)o(guments)f(and)
h(returns)e(the)i Fp(number)f Ft(of)g(the)h(attrib)o(ute.)454
2848 y Fn(\226)25 b Fr(SPI)p 597 2848 V 18 w(fname\(\))13
b Ft(takes)g(the)g(description)g(of)h(a)f(tuple)g(and)h(the)f
Fp(number)h Ft(of)f(an)h(attrib)o(ute)504 2907 y(as)f(ar)o(guments)f
(and)h(returns)e(the)i Fp(name)f Ft(of)g(the)g(attrib)o(ute.)454
2986 y Fn(\226)25 b Fr(SPI)p 597 2986 V 18 w(getvalue\(\))13
b Ft(takes)g(the)h(description)g(of)f(a)h(tuple,)h(the)e(tuple)h(and)g
(the)g(number)504 3046 y(of)k(an)g(attrib)o(ute)f(as)i(ar)o(guments)e
(and)i(returns)e(a)h Fp(string)h(r)n(epr)n(esentation)g
Ft(of)e(the)h(gi)o(v)o(en)504 3106 y(attrib)o(ute')m(s)12
b(v)o(alue.)454 3185 y Fn(\226)25 b Fr(SPI)p 597 3185
V 18 w(getbinval\(\))10 b Ft(takes)h(the)g(description)g(of)f(a)i
(tuple,)f(the)h(tuple)e(and)i(the)f(number)504 3244 y(of)h(an)h(attrib)
o(ute)e(as)i(ar)o(guments)f(and)g(returns)g(the)h(binary)e(v)o(alue)h
(of)g(the)h(gi)o(v)o(en)f(attrib)o(ute.)454 3323 y Fn(\226)25
b Fr(SPI)p 597 3323 V 18 w(gettype\(\))11 b Ft(returns)h(a)h(copy)e(of)
h(the)h(type)f(name)g(for)g(the)g(speci\002ed)h(attrib)o(ute.)454
3402 y Fn(\226)25 b Fr(SPI)p 597 3402 V 18 w(gettypeid\(\))11
b Ft(returns)h(the)g(type)g(OID)g(for)g(the)g(speci\002ed)h(attrib)o
(ute.)p eop
%%Page: 47 47
47 46 bop 198 60 a Fm(2.5.)26 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)343
b Ft(47)382 234 y Fn(\226)25 b Fr(SPI)p 525 234 15 2
v 18 w(getrelname\(\))11 b Ft(returns)h(the)g(name)g(of)g(the)h
(speci\002ed)f(relation.)382 315 y Fn(\226)25 b Fr(SPI)p
525 315 V 18 w(palloc\(\))e Ft(allocates)i(memory)m(.)50
b(In)23 b(contrast)h(to)g Fr(malloc\(\))g Ft(\(normally)432
375 y(used\))15 b(it)g(allocates)h(memory)e(in)h(such)h(a)f(way)g(that)
g(it)g(can)g(be)g(freed)g(automatically)f(by)432 434
y Fr(SPI)p 525 434 V 18 w(finish\(\))p Ft(.)382 515 y
Fn(\226)25 b Fr(SPI)p 525 515 V 18 w(repalloc\(\))12
b Ft(reallocates)i(memory)f(that)h(has)g(originally)f(been)g(allocated)
h(us-)432 575 y(ing)e Fr(SPI)p 601 575 V 18 w(palloc\(\))p
Ft(.)382 656 y Fn(\226)25 b Fr(SPI)p 525 656 V 18 w(pfree\(\))11
b Ft(frees)i(memory)e(allocated)h(by)h Fr(SPI)p 1397
656 V 17 w(palloc\(\))p Ft(.)198 778 y Fn(Example)g(2.12)25
b Ft(W)l(e)14 b(want)g(PostgreSQL)f(to)h(automatically)g(generate)g(a)g
(v)o(alue)g(for)f(the)i(supplier)e(id)198 838 y Fr(sno)e
Ft(whene)o(v)o(er)g(a)g(ne)o(w)h(tuple)f(is)g(inserted)g(into)g(table)g
Fr(supplier)p Ft(.)k(Therefore)c(we)g(de\002ne)g(a)h
Fp(trigger)198 898 y(function)k Fr(trigf)p 531 898 V
17 w(sno\(\))g Ft(that)g(is)g(called)h(before)e(the)i(e)o(x)o(ecution)f
(of)g(e)o(v)o(ery)g Fr(insert)g Ft(statement.)198 958
y Fr(trigf)p 351 958 V 17 w(sno\(\))c Ft(has)h(to)f(perform)f(the)i
(follo)o(wing)d(steps:)273 1059 y Fo(\017)25 b Ft(establish)12
b(a)h(connection)f(to)g(the)g(PostgreSQL)g(backend)g(using)h
Fr(SPI)p 1547 1059 V 17 w(connect\(\))273 1161 y Fo(\017)25
b Ft(get)12 b(the)g(greatest)h(supplier)f(id)g Fr(sno)g
Ft(contained)g(in)g(table)g Fr(supplier)g Ft(using)g
Fr(SPI)p 1794 1161 V 18 w(exec\(\))273 1262 y Fo(\017)25
b Ft(modify)13 b(attrib)o(ute)h Fr(sno)h Ft(of)g(the)f(tuple)h(to)g(be)
g(inserted)f(to)h(contain)g(the)g(ne)o(xt)g(greater)f(number)323
1322 y(using)e Fr(SPI)p 536 1322 V 18 w(modifytuple\(\))273
1424 y Fo(\017)25 b Ft(disconnect)12 b(from)f(the)i(backend)f(using)g
Fr(SPI)p 1122 1424 V 18 w(finish\(\))273 1526 y Fo(\017)25
b Ft(return)11 b(the)h(modi\002ed)g(tuple)198 1627 y(Here)26
b(are)h(the)f(contents)h(of)f(function)g Fr(trigf)p 1103
1627 V 17 w(sno\(\))g Ft(that)h(can)f(be)h(appended)f(to)h(the)f
(\002le)198 1687 y Fr(trigger.c)11 b Ft(from)h(e)o(xample)g(2.11:)258
1788 y Fr(HeapTuple)258 1848 y(trigf_sno\(\))258 1908
y({)30 b(HeapTuple)208 b(rettuple;)318 1968 y(bool)358
b(isnull;)318 2027 y(int)388 b(ret,)29 b(max;)318 2087
y(int)388 b(atts_to_be_changed[1];)318 2147 y(Datum)328
b(new_value[1];)318 2207 y(char)358 b(nulls;)318 2326
y(if)29 b(\(!CurrentTriggerData\))377 2386 y(elog\(ERROR,)527
2446 y("trigf:)g(triggers)g(are)g(not)h(initialized"\);)318
2565 y(/*)f(This)h(is)f(the)h(tuple)f(to)h(be)g(inserted)f(*/)318
2625 y(rettuple)g(=)g(CurrentTriggerData->tg_trigtuple;)318
2745 y(/*)g(Connect)g(to)h(backend)f(*/)318 2804 y(if)g(\(\(ret)h(=)f
(SPI_connect\(\)\))g(<)g(0\))377 2864 y(elog\(ERROR,)527
2924 y("trigf_sno:)f(SPI_connect)h(returned)g(\045d",ret\);)318
3044 y(/*)g(Get)h(greatest)f(sno)g(in)h(relation)f(supplier)g(*/)318
3103 y(/*)g(Execute)g(the)h(query)f(*/)318 3163 y(ret)g(=)h
(SPI_exec\("select)e(max\(sno\))h(from)g(supplier",0\);)318
3223 y(if)g(\(ret)h(<)f(0\))407 3283 y(elog\(ERROR,)557
3342 y("trigf_sno:)f(SPI_exec)h(returned)g(\045d",ret\);)p
eop
%%Page: 48 48
48 47 bop 270 60 a Ft(48)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)390
234 y Fr(/*)29 b(extract)g(the)h(number)f(from)h(the)f(result)419
294 y(*)h(returned)f(by)h(the)f(query.)h(SPI_exec\(\))e(puts)419
354 y(*)i(the)g(result)f(into)g(the)h(global)f(structure)419
413 y(*)h(SPI_tuptable)f(*/)390 473 y(max)g(=)h
(SPI_getbinval\(SPI_tuptable->val)o(s[0],)987 533 y
(SPI_tuptable->tupdesc,)e(1,)987 593 y(&isnull\);)390
712 y(/*)h(disconnect)g(from)g(backend)h(*/)390 772 y(SPI_finish\(\);)
390 892 y(/*)f(array)h(containing)e(the)i(numbers)f(of)h(attributes)419
951 y(*)g(to)g(be)g(changed:)f(sno)g(has)h(attno)f(1)h(*/)390
1011 y(atts_to_be_changed[0])d(=)j(1;)390 1131 y(/*)f(new)h(values)f
(for)h(attributes)e(to)i(be)g(changed:)419 1191 y(*)g(the)g(next)f
(number)g(for)h(sno)g(is)f(max+1)h(*/)390 1250 y(new_value[0])e(=)i
(\(max+1\);)390 1370 y(/*)f(modify)g(the)h(tuple)f(to)h(be)g(inserted)f
(to)g(contain)419 1430 y(*)h(max+1)g(as)f(sno)h(*/)390
1489 y(rettuple)f(=)449 1549 y(SPI_modifytuple\(CurrentTriggerData-)o
(>tg_relat)o(ion,)928 1609 y(rettuple,)928 1669 y(1,)928
1729 y(atts_to_be_changed,)928 1788 y(new_value,)928
1848 y(&nulls\);)390 1968 y(if)g(\(rettuple)g(==)h(NULL\))479
2027 y(elog\(ERROR,)629 2087 y("trigf_sno:)e(SPI_modifytuple)h
(failed"\);)390 2207 y(CurrentTriggerData)e(=)j(NULL;)390
2267 y(return)f(\(rettuple\);)330 2326 y(})270 2456 y
Ft(W)l(e)13 b(again)f(create)g(the)g(shared)h(library)e
Fr(trigger.so)g Ft(out)i(of)e Fr(trigger.c)p Ft(:)330
2595 y Fr($)30 b(gcc)f(-I$PGROOT/include)f(-I$PGSRC/include/)g(-fpic)h
(\\)330 2655 y(>)h(-c)f(trigger.c)g(-o)h(trigger.o)330
2714 y($)g(gcc)f(-shared)g(-o)h(trigger.so)f(trigger.o)270
2844 y Ft(Ne)o(xt)16 b(we)g(ha)o(v)o(e)h(to)f(make)f(the)h(function)f
Fr(trigf)p 1155 2844 15 2 v 18 w(sno\(\))g Ft(kno)o(wn)g(to)h
(PostgreSQL)g(and)g(after)f(that)270 2904 y(we)j(can)f(de\002ne)h(the)f
(trigger)g Fr(sno)p 894 2904 V 17 w(before)g Ft(which)h(is)f(called)h
(before)f(an)g Fr(insert)g Ft(to)h(the)f(table)270 2963
y Fr(supplier)p Ft(.)30 b(The)18 b(trigger)e(function)g(ensures)i(that)
f(the)h(ne)o(xt)f(greater)g(number)f(for)h Fr(sno)g Ft(will)g(be)270
3023 y(used.)330 3162 y Fr(testdb=>)29 b(create)g(function)g
(trigf_sno\(\))g(returns)g(opaque)330 3222 y(testdb->)g(as)g
('/<where_ever_you_put_it>/trigger.so)o(')330 3282 y(testdb->)g
(language)g('c';)330 3342 y(CREATE)p eop
%%Page: 49 49
49 48 bop 198 60 a Fm(2.5.)29 b(SOME)12 b(OF)h(POSTGRESQL)-5
b('S)12 b(SPECIAL)h(FEA)-6 b(TURES)14 b(IN)e(DET)-5 b(AIL)340
b Ft(49)258 234 y Fr(testdb=>)29 b(create)g(trigger)g(sno_before)258
294 y(testdb->)g(before)g(insert)g(on)h(supplier)258
354 y(testdb->)f(for)g(each)h(row)f(execute)g(procedure)g
(trigf_sno\(\);)258 413 y(CREATE)258 473 y(testdb=>)198
585 y Ft(Ev)o(ery)12 b(time)f(a)h(ne)o(w)g(tuple)f(is)h(inserted)f(to)h
(the)f(table)h Fr(supplier)f Ft(a)h(ne)o(w)f Fr(sno)h
Ft(is)g(assigned)g(automat-)198 645 y(ically)g(re)o(gardless)h(of)e
(the)i(v)o(alue)f(gi)o(v)o(en)g(in)g(the)h Fr(insert)e
Ft(statement:)258 747 y Fr(testdb=>)29 b(select)g(*)h(from)f(supplier;)
258 806 y(sno|sname)g(|city)258 866 y(---+------+------)318
926 y(1|Smith)g(|London)318 986 y(2|Jones)g(|Paris)318
1046 y(3|Adams)g(|Vienna)318 1105 y(4|Blake)g(|Rome)258
1165 y(\(4)g(rows\))258 1285 y(testdb=>)g(insert)g(into)g(supplier)258
1344 y(testdb->)g(\(sno,)g(sname,)g(city\))258 1404 y(testdb->)g
(values)g(\(200,'Cook',)g('Boston'\);)258 1464 y(INSERT)g(15606)g(1)258
1584 y(testdb=>)g(select)g(*)h(from)f(supplier;)258 1643
y(sno|sname)g(|city)258 1703 y(---+------+------)318
1763 y(1|Smith)g(|London)318 1823 y(2|Jones)g(|Paris)318
1882 y(3|Adams)g(|Vienna)318 1942 y(4|Blake)g(|Rome)318
2002 y(5|Cook)59 b(|Boston)258 2062 y(\(5)29 b(rows\))258
2181 y(testdb=>)198 2327 y Fh(2.5.8)59 b(Rules)15 b(in)g(P)o(ostgr)o
(eSQL)198 2421 y Ft(PostgreSQL)f(supports)f(a)i(po)o(werful)d
Fp(rule)j(system)p Ft(.)21 b(The)15 b(user)f(can)g(de\002ne)g(a)g(rule)
f(and)h(connect)g(it)g(to)198 2481 y(an)g(e)o(v)o(ent.)19
b(Whene)o(v)o(er)13 b(the)h(e)o(v)o(ent)f(occurs)h(the)g(rule)f(body)g
(is)h(e)o(x)o(ecuted)g(in)f(addition)g(to)h(or)f(instead)h(of)198
2541 y(the)e(commands)h(of)f(the)g(e)o(v)o(ent.)198 2661
y(A)g(rule)g(is)h(created)f(using)h(the)f(follo)o(wing)f(SQL)h
(statement:)258 2762 y Fr(create)29 b(rule)g(rule_name)258
2822 y(as)g(on)h(event)258 2882 y(to)f(object)h([where)f(clause])258
2942 y(do)g([instead])258 3002 y([action)g(|)h(nothing)f(|)h
([actions...]])198 3103 y Ft(where)20 b Fr(event)f Ft(is)h(one)g(of)f
Fr(select,)29 b(update,)g(delete)19 b Ft(or)h Fr(insert)p
Ft(.)39 b Fr(object)19 b Ft(is)h(the)198 3163 y(name)14
b(of)g(a)h Fp(table)f Ft(or)f Fp(table)o(.column)p Ft(.)22
b(The)15 b Fr(where)f Ft(clause,)i(and)e(the)g Fr(action)g
Ft(are)g(a)g(normal)g(SQL)198 3222 y Fr(where)e Ft(clause)h(and)f
(collection)g(of)g(SQL)h(commands.)273 3283 y(One)k(application)g(of)h
(rules)f(is)h(the)g(implementation)e(of)h Fp(vie)o(ws)i
Ft(in)e(PostgreSQL.)h(A)g Fp(vie)o(w)g Ft(is)g(a)198
3342 y Fp(virtual)e Ft(table)g(that)g(does)g(not)g(physically)g(e)o
(xist)g(within)g(the)g(database)g(b)o(ut)g(looks)g(to)g(the)g(user)g
(as)h(if)198 3402 y(it)f(did.)28 b(T)l(o)17 b(realize)f(a)h
Fp(vie)o(w)g Ft(we)g(can)f(create)h(an)f(empty)g(table)h(with)f(the)g
(name)h(of)f(the)g Fp(vie)o(w)p Ft(.)29 b(Then)p eop
%%Page: 50 50
50 49 bop 270 60 a Ft(50)307 b Fm(CHAPTER)14 b(2.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(USER'S)e(POINT)g(OF)g(VIEW)270
234 y Ft(we)h(de\002ne)g(a)g(rule)g(that)f(is)i(\002red)e(e)o(v)o(ery)h
(time)f(the)h(ne)o(w)g(table)g(is)g(accessed.)19 b(Instead)13
b(of)g(retrie)o(ving)e(the)270 294 y(data)k(from)e(the)i
Fp(virtual)f Ft(table)h(the)f(rule)g(body)g(is)h(e)o(x)o(ecuted)g
(retrie)o(ving)e(the)i(data)g(from)e(one)i(or)f(more)270
354 y(physically)e(stored)g(tables.)270 473 y Fn(Example)h(2.13)25
b Ft(W)l(e)15 b(want)g(to)g(sho)o(w)g(ho)o(w)g(a)g(vie)o(w)g(could)g
(be)h(realized)f(in)g(PostgreSQL.)g(Note)g(that)270 533
y(there)d(is)i(of)e(course)h(an)g(o)o(wn)f(command)g(to)h(create)g
Fp(vie)o(ws)h Fr(create)29 b(view)12 b Ft(in)h(PostgreSQL)f(which)270
593 y(performs)f(the)i(steps)g(of)f(our)f(e)o(xample)i(internally)m(.)
270 712 y(First)f(we)g(create)h(a)f(ne)o(w)m(,)h(empty)f(table)g
Fr(my)p 1023 712 15 2 v 18 w(view)p Ft(:)330 812 y Fr(testdb=>)29
b(create)g(table)g(my_view)g(\()330 872 y(testdb->)g(sname)g
(varchar\(20\),)330 932 y(testdb->)g(pname)g(varchar\(20\))330
991 y(testdb->)g(\);)270 1091 y Ft(Ne)o(xt)14 b(we)g(create)g(the)g
(rule)f(that)h(will)f(be)h(\002red)f(whene)o(v)o(er)h(a)g
Fr(select)f Ft(against)h(the)g(table)g Fr(my)p 1936 1091
V 17 w(view)270 1151 y Ft(sho)o(ws)f(up:)330 1250 y Fr(testdb=>)29
b(create)g(rule)g(my_view_rule)330 1310 y(testdb->)g(as)g(on)h(select)f
(to)h(my_view)330 1370 y(testdb->)f(do)g(instead)h(select)f(s.sname,)g
(p.pname)330 1430 y(testdb->)g(from)g(supplier)g(s,)h(part)f(p,)h
(sells)f(se)330 1489 y(testdb->)g(where)g(s.sno=se.sno)g(and)g
(p.pno=se.pno;)330 1549 y(CREATE)330 1609 y(testdb=>)270
1709 y Ft(No)o(w)12 b(we)h(can)f(use)h(the)f(table)h
Fr(my)p 855 1709 V 17 w(view)f Ft(as)h(if)f(it)g(were)h(populated)e
(with)i(tuples:)330 1808 y Fr(testdb=>)29 b(select)g(*)h(from)f
(my_view;)330 1868 y(sname)g(|pname)330 1928 y(------+-----)330
1988 y(Smith)g(|Screw)330 2047 y(Smith)g(|Nut)330 2107
y(Jones)g(|Cam)330 2167 y(Adams)g(|Screw)330 2227 y(Adams)g(|Bolt)330
2286 y(Blake)g(|Nut)330 2346 y(Blake)g(|Bolt)330 2406
y(Blake)g(|Cam)330 2466 y(\(8)g(rows\))330 2585 y(testdb=>)g(select)g
(*)h(from)f(my_view)330 2645 y(testdb->)g(where)g(sname)g(=)h('Blake';)
330 2705 y(sname)f(|pname)330 2765 y(------+-----)330
2824 y(Blake)g(|Nut)330 2884 y(Blake)g(|Bolt)330 2944
y(Blake)g(|Cam)330 3004 y(\(3)g(rows\))330 3123 y(testdb=>)p
eop
%%Page: 51 51
51 50 bop 198 608 a Fj(Chapter)26 b(3)198 857 y Fq(P)n(ostgr)n(eSQL)k
(fr)n(om)i(the)198 1006 y(Pr)n(ogrammer')-5 b(s)32 b(P)n(oint)f(of)g(V)
-5 b(iew)198 1265 y Ft(This)10 b(chapter)f(gi)o(v)o(es)h(an)f(o)o(v)o
(ervie)o(w)g(of)g(the)h(internal)e(structure)h(of)g(the)g(backend)g(of)
g(PostgreSQL.)h(After)198 1325 y(ha)o(ving)15 b(read)g(the)h(follo)o
(wing)e(sections)i(you)f(should)g(ha)o(v)o(e)h(an)f(idea)h(of)f(ho)o(w)
g(a)h(query)e(is)i(processed.)198 1385 y(Don')o(t)g(e)o(xpect)g(a)h
(detailed)f(description)g(here)g(\(I)g(think)g(such)g(a)h(description)f
(dealing)g(with)g(all)g(data)198 1445 y(structures)11
b(and)h(functions)f(used)h(within)f(PostgreSQL)g(would)g(e)o(xceed)h
(1000)f(pages!\).)k(This)d(chapter)198 1504 y(is)f(intended)f(to)g
(help)g(understanding)g(the)g(general)h(control)e(and)i(data)f(\003o)o
(w)g(within)g(the)g(backend)g(from)198 1564 y(recei)o(ving)i(a)g(query)
g(to)g(sending)h(the)f(results.)198 1729 y Fi(3.1)71
b(The)18 b(W)-5 b(ay)18 b(of)f(a)h(Query)198 1841 y Ft(Here)12
b(we)h(gi)o(v)o(e)f(a)h(short)f(o)o(v)o(ervie)o(w)g(of)g(the)g(stages)h
(a)g(query)f(has)g(to)h(pass)g(in)f(order)g(to)g(obtain)g(a)g(result:)
273 1927 y Fo(\017)25 b Ft(First)14 b(a)h(connection)f(from)g(an)h
(application)f(program)g(to)g(the)h(PostgreSQL)f(serv)o(er)h(has)g(to)g
(be)323 1987 y(established.)g(The)d(application)f(program)f(transmits)i
(a)f(query)g(to)g(the)h(serv)o(er)f(and)g(recei)o(v)o(es)h(the)323
2047 y(results)g(sent)h(back)f(by)h(the)f(serv)o(er)m(.)273
2140 y Fo(\017)25 b Ft(The)17 b Fp(parser)g(stage)f Ft(checks)i(the)e
(query)h(transmitted)f(by)h(the)f(application)h(program)e(\(client\))
323 2200 y(for)c(correct)h(syntax)g(and)h(creates)f(a)h
Fp(query)g(tr)n(ee)p Ft(.)273 2293 y Fo(\017)25 b Ft(The)18
b Fp(r)n(e)o(write)h(system)f Ft(takes)f(the)h Fp(query)g(tr)n(ee)g
Ft(created)g(by)f(the)h Fp(parser)g(stage)f Ft(looks)g(for)g(an)o(y)323
2352 y Fp(rules)11 b Ft(\(stored)g(in)g(the)g Fp(system)h(catalogs)p
Ft(\))e(to)h(apply)f(to)h(the)g Fp(querytr)n(ee)i Ft(and)e(performs)f
(the)h(trans-)323 2412 y(formations)j(gi)o(v)o(en)g(in)h(the)g
Fp(rule)h(bodies)p Ft(.)24 b(One)15 b(application)g(of)f(the)h
Fp(r)n(e)o(write)i(system)f Ft(is)f(gi)o(v)o(en)323 2472
y(in)f(the)g(realization)f(of)h Fp(vie)o(ws)p Ft(.)23
b(Whene)o(v)o(er)14 b(a)g(query)g(against)g(a)g Fp(vie)o(w)h
Ft(\(i.e.)22 b(a)14 b Fp(virtual)g(table)p Ft(\))g(is)323
2532 y(made,)h(the)f Fp(r)n(e)o(write)h(system)g Ft(re)o(writes)f(the)g
(user')m(s)h(query)e(to)h(a)h(query)f(that)g(accesses)i(the)e
Fp(base)323 2592 y(tables)e Ft(gi)o(v)o(en)g(in)g(the)h
Fp(vie)o(w)g(de\002nition)e Ft(instead.)273 2685 y Fo(\017)25
b Ft(The)17 b Fp(planner/optimizer)f Ft(takes)h(the)g(\()p
Fp(r)n(e)o(written)p Ft(\))f Fp(querytr)n(ee)i Ft(and)f(creates)g(a)g
Fp(queryplan)f Ft(that)323 2744 y(will)10 b(be)i(the)f(input)f(to)h
(the)g Fp(e)o(xecutor)p Ft(.)16 b(It)11 b(does)h(so)f(by)g(\002rst)g
(creating)g(all)g(possible)g Fp(paths)g Ft(leading)323
2804 y(to)16 b(the)g(same)h(result.)29 b(\()16 b(F)o(or)g(e)o(xample)h
(if)f(there)g(is)h(an)f(inde)o(x)h(on)f(a)h(relation)f(to)g(be)h
(scanned,)323 2864 y(there)c(are)g(two)g Fp(paths)h Ft(for)f(the)g
(scan.)20 b(One)14 b(possibility)f(is)h(a)g(simple)g(sequential)f(scan)
i(and)e(the)323 2924 y(other)g(possibility)g(is)h(to)f(use)h(the)g
(inde)o(x.\))19 b(Ne)o(xt)14 b(the)f(cost)h(for)f(the)h(e)o(x)o
(ecution)f(of)h(each)g Fp(plan)f Ft(is)323 2984 y(estimated)f(and)g
(the)h(cheapest)g Fp(plan)f Ft(is)g(chosen)h(and)f(handed)h(back.)273
3077 y Fo(\017)25 b Ft(The)14 b Fp(e)o(xecutor)h Ft(recursi)o(v)o(ely)f
(steps)h(through)e(the)h Fp(plan)g(tr)n(ee)h Ft(and)f(retrie)o(v)o(es)g
(tuples)g(in)g(the)h(way)323 3136 y(represented)f(by)g(the)g
Fp(plan)p Ft(.)21 b(The)15 b Fp(e)o(xecutor)g Ft(makes)f(use)h(of)f
(the)g Fp(stor)o(age)h(system)g Ft(while)f(scan-)323
3196 y(ning)i(relations,)j(performs)d Fp(sorts)i Ft(and)f
Fp(joins)p Ft(,)i(e)o(v)o(aluates)e Fp(quali\002cations)g
Ft(and)g(\002nally)g(hands)323 3256 y(back)12 b(the)g(tuples)h(deri)o
(v)o(ed.)198 3342 y(In)j(the)g(follo)o(wing)g(sections)h(we)f(will)g
(co)o(v)o(er)h(e)o(v)o(ery)f(of)g(the)h(abo)o(v)o(e)g(listed)f(items)h
(in)f(more)g(detail)g(to)198 3402 y(gi)o(v)o(e)c(a)h(better)f
(understanding)f(on)i(PostgreSQL)-5 b(')m(s)12 b(internal)g(control)f
(and)i(data)f(structures.)1073 3552 y(51)p eop
%%Page: 52 52
52 51 bop 270 60 a Ft(52)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Fi(3.2)71 b(Ho)o(w)18 b(Connections)f(ar)o(e)g(Established)270
370 y Ft(PostgreSQL)c(is)g(implemented)f(using)h(a)g(simple)g
(\224process)h(per)o(-user\224)e(client/serv)o(er)h(model.)k(In)c(this)
270 430 y(model)k(there)f(is)h(one)g Fp(client)g(pr)n(ocess)h
Ft(connected)f(to)f(e)o(xactly)i(one)e Fp(server)j(pr)n(ocess)p
Ft(.)30 b(As)18 b(we)f(don')o(t)270 490 y(kno)o(w)f Fp(per)h(se)g
Ft(ho)o(w)f(man)o(y)h(connections)g(will)f(be)g(made,)j(we)d(ha)o(v)o
(e)h(to)g(use)g(a)f Fp(master)i(pr)n(ocess)f Ft(that)270
549 y(spa)o(wns)h(a)e(ne)o(w)h Fp(server)h(pr)n(ocess)f
Ft(e)o(v)o(ery)f(time)h(a)f(connection)h(is)f(requested.)29
b(This)17 b Fp(master)g(pr)n(ocess)270 609 y Ft(is)f(called)g
Fr(postmaster)e Ft(and)i(listens)g(at)f(a)h(speci\002ed)g(TCP/IP)f
(port)g(for)g(incoming)g(connections.)270 669 y(Whene)o(v)o(er)e(a)h
(request)f(for)f(a)i(connection)f(is)h(detected)f(the)g
Fr(postmaster)g Ft(process)g(spa)o(wns)i(a)e(ne)o(w)270
729 y Fp(server)i(pr)n(ocess)f Ft(called)g Fr(postgres)p
Ft(.)j(The)d(serv)o(er)g(tasks)g(\()p Fr(postgres)e Ft(processes\))i
(communicate)270 788 y(with)k(each)g(other)f(using)h
Fp(semaphor)n(es)h Ft(and)f Fp(shar)n(ed)h(memory)g Ft(to)e(ensure)h
(data)g(inte)o(grity)f(through-)270 848 y(out)j(concurrent)e(data)i
(access.)40 b(Figure)19 b(3.1)h(illustrates)f(the)h(interaction)f(of)g
(the)h(master)g(process)270 908 y Fr(postmaster)11 b
Ft(the)i(serv)o(er)f(process)h Fr(postgres)e Ft(and)i(a)f(client)h
(application.)345 981 y(The)e(client)g(process)g(can)h(either)e(be)h
(the)g Fr(psql)g Ft(frontend)f(\(for)f Fp(inter)o(active)j
Ft(SQL)f(queries\))f(or)h(an)o(y)270 1041 y(user)f(application)f
(implemented)g(using)h(the)f Fr(libpg)h Ft(library)m(.)j(Note)d(that)f
(applications)h(implemented)270 1100 y(using)i Fr(ecpq)g
Ft(\(i.e.)k(the)d(postgres)f(embedded)g(C)h(compiler\))e(also)i(use)g
(this)f(library)m(.)345 1173 y(Once)e(a)g(connection)f(is)i
(established)f(the)g(client)f(process)i(can)f(send)g(a)g(query)f(to)h
(the)g Fp(bac)o(kend)p Ft(.)15 b(The)270 1233 y(query)f(is)h
(transmitted)e(using)i Fp(plain)f(te)o(xt)p Ft(,)h(i.e.)23
b(there)14 b(is)h(no)f(parsing)g(done)h(in)f(the)h Fp(fr)n(ontend)f
Ft(\(client\).)270 1293 y(The)i(serv)o(er)g Fp(parses)g
Ft(the)g(query)m(,)g(creates)g(an)g Fp(e)o(xecution)f(plan)p
Ft(,)i(e)o(x)o(ecutes)g(the)e Fp(plan)g Ft(and)h(returns)f(the)270
1352 y(retrie)o(v)o(ed)c(tuples)i(to)f(the)g(client)h(by)f
(transmitting)f(them)h(o)o(v)o(er)h(the)f(established)h(connection.)543
2309 y @beginspecial 180 @llx 310 @lly 431 @urx 482 @ury
2510 @rwi @setspecial
%%BeginDocument: figures/connection.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
175.5 498.0 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawEllipse {
	/endangle exch def
	/startangle exch def
	/yrad exch def
	/xrad exch def
	/y exch def
	/x exch def
	/savematrix mtrx currentmatrix def
	x y tr xrad yrad sc 0 0 1 startangle endangle arc
	closepath
	savematrix setmatrix
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 2835 1980 m 3645 1980 l 3645 2250 l 2835 2250 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2925 2160 m
gs 1 -1 sc (Postmaster) col-1 sh gr
% Polyline
n 2790 540 m 3600 540 l 3600 810 l 2790 810 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2880 720 m
gs 1 -1 sc (Postmaster) col-1 sh gr
% Ellipse
n 3240 2385 810 585 0 360 DrawEllipse gs col-1 s gr

% Ellipse
n 2520 2115 45 45 0 360 DrawEllipse gs col-1 s gr

% Ellipse
n 900 2206 765 495 0 360 DrawEllipse gs col-1 s gr

% Ellipse
n 3195 945 810 585 0 360 DrawEllipse gs col-1 s gr

% Ellipse
n 2475 675 45 45 0 360 DrawEllipse gs col-1 s gr

% Ellipse
n 855 766 765 495 0 360 DrawEllipse gs col-1 s gr

% Polyline
gs  clippath
2704 2493 m 2809 2556 l 2686 2550 l 2840 2598 l 2858 2541 l  cp clip
n 1395 2115 m 2835 2565 l gs col-1 s gr gr

% arrowhead
n 2704 2493 m 2809 2556 l 2686 2550 l 2695 2521 l 2704 2493 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2565 2115 m 2835 2115 l gs col-1 s gr 
% Polyline
n 855 1890 m 855 2340 l gs col-1 s gr 
% Polyline
n 405 1890 m 1395 1890 l 1395 2340 l 405 2340 l cp gs col-1 s gr 
% Polyline
n 2835 2430 m 3645 2430 l 3645 2700 l 2835 2700 l cp gs col-1 s gr 
% Polyline
gs  clippath
2283 645 m 2403 675 l 2283 705 l 2445 705 l 2445 645 l  cp clip
n 1350 675 m 2430 675 l gs col-1 s gr gr

% arrowhead
n 2283 645 m 2403 675 l 2283 705 l 2283 675 l 2283 645 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2520 675 m 2790 675 l gs col-1 s gr 
% Polyline
n 810 450 m 810 900 l gs col-1 s gr 
% Polyline
n 360 450 m 1350 450 l 1350 900 l 360 900 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2880 2880 m
gs 1 -1 sc (Server Host) col-1 sh gr
/Times-Roman ff 150.00 scf sf
495 2070 m
gs 1 -1 sc (User ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
495 2265 m
gs 1 -1 sc (App) col-1 sh gr
/Times-Roman ff 150.00 scf sf
900 2160 m
gs 1 -1 sc (LIBPQ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
585 2610 m
gs 1 -1 sc (Client Host) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 2610 m
gs 1 -1 sc (Postgres) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2835 1440 m
gs 1 -1 sc (Server Host) col-1 sh gr
/Times-Roman ff 150.00 scf sf
450 630 m
gs 1 -1 sc (User ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
450 825 m
gs 1 -1 sc (App) col-1 sh gr
/Times-Roman ff 150.00 scf sf
855 720 m
gs 1 -1 sc (LIBPQ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1170 m
gs 1 -1 sc (Client Host) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 733 2418 a(Figure)e(3.1:)16 b(Ho)o(w)c(a)g(connection)g
(is)h(established)270 2780 y Fi(3.3)71 b(The)18 b(P)o(arser)f(Stage)270
2916 y Ft(The)c Fp(parser)g(stage)f Ft(consists)h(of)f(two)f(parts:)345
3055 y Fo(\017)25 b Ft(The)17 b Fp(parser)g Ft(de\002ned)g(in)f
Fr(gram.y)h Ft(and)f Fr(scan.l)h Ft(is)g(b)o(uilt)f(using)h(the)f(UNIX)
h(tools)f Fr(yacc)395 3115 y Ft(and)c Fr(lex)p Ft(.)345
3266 y Fo(\017)25 b Ft(The)11 b Fp(tr)o(ansformation)g(pr)n(ocess)h
Ft(does)f(some)g(necessary)h(transformation)d(to)i(the)g(data)g
(structure)395 3326 y(returned)g(by)h(the)h Fp(parser)p
Ft(.)p eop
%%Page: 53 53
53 52 bop 198 60 a Fm(3.3.)29 b(THE)13 b(P)-5 b(ARSER)13
b(ST)-5 b(A)n(GE)1189 b Ft(53)198 234 y Fh(3.3.1)59 b(P)o(arser)198
328 y Ft(The)14 b Fp(parser)g Ft(has)g(to)f(check)h(the)f(query)g
(string)g(\(which)g(arri)o(v)o(es)g(as)h Fp(plain)f(ASCII)h(te)o(xt)p
Ft(\))f(for)f(v)o(alid)h(syn-)198 388 y(tax.)22 b(If)14
b(the)g(syntax)h(is)g(correct)e(a)i Fp(parse)g(tr)n(ee)g
Ft(is)g(b)o(uilt)f(up)g(and)h(handed)f(back)h(otherwise)f(an)g(error)g
(is)198 448 y(returned.)h(F)o(or)d(the)g(implementation)f(the)i(well)f
(kno)o(wn)g(UNIX)g(tools)g Fr(lex)g Ft(and)g Fr(yacc)g
Ft(are)h(used.)273 508 y(The)i Fp(le)o(xer)g Ft(is)g(de\002ned)f(in)h
(the)f(\002le)g Fr(scan.l)g Ft(and)h(is)g(responsible)f(for)g
(recognizing)g Fp(identi\002ers)p Ft(,)198 567 y(the)h
Fp(SQL)g(ke)o(ywor)n(ds)h Ft(etc.)24 b(F)o(or)15 b(e)o(v)o(ery)g
Fp(ke)o(ywor)n(d)g Ft(or)g Fp(identi\002er)g Ft(that)g(is)h(found,)g(a)
f Fp(token)g Ft(is)g(generated)198 627 y(and)d(handed)h(to)f(the)g
Fp(parser)p Ft(.)273 687 y(The)k Fp(parser)g Ft(is)g(de\002ned)f(in)g
(the)h(\002le)f Fr(gram.y)g Ft(and)g(consists)i(of)e(a)h(set)g(of)f
Fp(gr)o(ammar)h(rules)g Ft(and)198 747 y Fp(actions)10
b Ft(that)g(are)g(e)o(x)o(ecuted)h(whene)o(v)o(er)f(a)h(rule)f(is)g
(\002red.)15 b(The)10 b(code)h(of)f(the)g Fp(actions)g
Ft(\(which)g(is)g(actually)198 807 y(C-code\))i(is)h(used)f(to)h(b)o
(uild)e(up)i(the)f Fp(parse)h(tr)n(ee)p Ft(.)273 867
y(The)h(\002le)g Fr(scan.l)f Ft(is)h(transformed)f(to)g(the)h(C-source)
g(\002le)g Fr(scan.c)f Ft(using)h(the)g(program)e Fr(lex)198
927 y Ft(and)17 b Fr(gram.y)g Ft(is)h(transformed)e(to)h
Fr(gram.c)g Ft(using)g Fr(yacc)p Ft(.)30 b(After)17 b(these)h
(transformations)e(ha)o(v)o(e)198 987 y(taken)11 b(place)g(a)g(normal)f
(C-compiler)g(can)h(be)h(used)f(to)g(create)g(the)g Fp(parser)p
Ft(.)16 b(Ne)o(v)o(er)11 b(make)f(an)o(y)i(changes)198
1046 y(to)j(the)g(generated)g(C-\002les)g(as)h(the)o(y)f(will)g(be)h(o)
o(v)o(erwritten)e(the)h(ne)o(xt)h(time)e Fr(lex)h Ft(or)g
Fr(yacc)g Ft(is)h(called.)198 1106 y(\(Note)g(that)h(the)g(mentioned)f
(transformations)g(and)h(compilations)f(are)h(normally)f(done)h
(automati-)198 1166 y(cally)12 b(using)h(the)f Fr(makefiles)f
Ft(shipped)i(with)f(the)g(PostgreSQL)g(source)h(distrib)o(ution.\))273
1226 y(A)20 b(detailed)g(description)g(of)g Fr(yacc)g
Ft(or)f(the)i Fp(gr)o(ammar)g(rules)g Ft(gi)o(v)o(en)f(in)g
Fr(gram.y)g Ft(would)f(be)198 1286 y(be)o(yond)c(the)h(scope)g(of)f
(this)h(paper)m(.)25 b(There)16 b(are)f(man)o(y)g(books)h(and)g
(documents)f(dealing)g(with)g Fr(lex)198 1345 y Ft(and)c
Fr(yacc)p Ft(.)k(Y)-5 b(ou)11 b(should)g(be)h(familiar)d(with)i
Fr(yacc)p Ft(,)h(before)e(you)h(start)g(to)h(study)f(the)g(grammar)f
(gi)o(v)o(en)198 1405 y(in)i Fr(gram.y)g Ft(otherwise)g(you)g(won')o(t)
g(understand)g(what)g(happens)h(there.)198 1525 y(F)o(or)27
b(a)h(better)f(understanding)g(of)g(the)g(data)h(structures)f(used)h
(in)g(PostgreSQL)f(for)g(the)g(pro-)198 1585 y(cessing)12
b(of)e(a)h(query)g(we)g(use)g(an)g(e)o(xample)h(to)e(illustrate)h(the)g
(changes)g(made)g(to)g(these)g(data)g(structures)198
1644 y(in)h(e)o(v)o(ery)g(stage.)198 1766 y Fn(Example)h(3.1)25
b Ft(This)10 b(e)o(xample)g(contains)f(the)h(follo)o(wing)e(simple)h
(query)g(that)h(will)f(be)g(used)h(in)g(v)o(arious)198
1825 y(descriptions)18 b(and)g(\002gures)g(throughout)f(the)h(follo)o
(wing)e(sections.)34 b(The)18 b(query)g(assumes)h(that)f(the)198
1885 y(tables)13 b(gi)o(v)o(en)f(in)g(e)o(xample)g(1.1)h(ha)o(v)o(e)g
(already)f(been)h(de\002ned.)258 1986 y Fr(select)29
b(s.sname,)g(se.pno)258 2046 y(from)g(supplier)g(s,)h(sells)f(se)258
2106 y(where)g(s.sno)g(>)h(2)g(and)437 2165 y(s.sno)f(=)h(se.sno;)198
2266 y Ft(Figure)13 b(3.2)h(sho)o(ws)h(the)e Fp(parse)i(tr)n(ee)f
Ft(b)o(uilt)g(by)f(the)h Fp(gr)o(ammar)h(rules)f Ft(and)g
Fp(actions)g Ft(gi)o(v)o(en)g(in)g Fr(gram.y)198 2326
y Ft(for)g(the)h(query)f(gi)o(v)o(en)h(in)f(e)o(xample)h(3.1)g
(\(without)f(the)h Fp(oper)o(ator)g(tr)n(ee)h Ft(for)e(the)g
Fp(wher)n(e)i(clause)f Ft(which)198 2385 y(is)f(sho)o(wn)f(in)h
(\002gure)f(3.3)h(because)g(there)f(was)h(not)f(enough)h(space)g(to)f
(sho)o(w)h(both)f(data)h(structures)f(in)198 2445 y(one)f(\002gure\).)
273 2505 y(The)f(top)g(node)g(of)f(the)h(tree)g(is)g(a)g
Fr(SelectStmt)f Ft(node.)15 b(F)o(or)10 b(e)o(v)o(ery)h(entry)f
(appearing)h(in)f(the)h Fp(fr)n(om)198 2565 y(clause)k
Ft(of)f(the)h(SQL)g(query)f(a)h Fr(RangeVar)e Ft(node)i(is)g(created)f
(holding)g(the)h(name)g(of)f(the)g Fp(alias)h Ft(and)198
2625 y(a)e(pointer)f(to)h(a)g Fr(RelExpr)f Ft(node)h(holding)f(the)h
(name)g(of)f(the)h Fp(r)n(elation)p Ft(.)k(All)c Fr(RangeVar)f
Ft(nodes)h(are)198 2685 y(collected)f(in)g(a)h(list)f(which)h(is)f
(attached)h(to)f(the)g(\002eld)g Fr(fromClause)g Ft(of)g(the)g
Fr(SelectStmt)f Ft(node.)273 2745 y(F)o(or)19 b(e)o(v)o(ery)g(entry)h
(appearing)f(in)g(the)h Fp(select)g(list)g Ft(of)g(the)f(SQL)h(query)f
(a)h Fr(ResTarget)f Ft(node)198 2804 y(is)e(created)g(holding)f(a)h
(pointer)f(to)h(an)g Fr(Attr)g Ft(node.)29 b(The)17 b
Fr(Attr)g Ft(node)f(holds)h(the)g Fp(r)n(elation)g(name)198
2864 y Ft(of)22 b(the)g(entry)g(and)h(a)f(pointer)g(to)g(a)h
Fr(Value)f Ft(node)g(holding)g(the)g(name)g(of)g(the)h
Fp(attrib)o(ute)p Ft(.)45 b(All)198 2924 y Fr(ResTarget)11
b Ft(nodes)h(are)g(collected)g(to)f(a)h(list)g(which)g(is)g(connected)g
(to)f(the)h(\002eld)g Fr(targetList)f Ft(of)198 2984
y(the)h Fr(SelectStmt)g Ft(node.)198 3103 y(Figure)28
b(3.3)i(sho)o(ws)f(the)g Fp(oper)o(ator)h(tr)n(ee)g Ft(b)o(uilt)e(for)g
(the)h Fp(wher)n(e)h(clause)g Ft(of)e(the)h(SQL)h(query)198
3163 y(gi)o(v)o(en)13 b(in)g(e)o(xample)h(3.1)f(which)g(is)h(attached)f
(to)g(the)h(\002eld)f Fr(qual)g Ft(of)g(the)g Fr(SelectStmt)f
Ft(node.)19 b(The)198 3223 y(top)f(node)g(of)g(the)g
Fp(oper)o(ator)h(tr)n(ee)g Ft(is)g(an)f Fr(A)p 970 3223
15 2 v 18 w(Expr)g Ft(node)g(representing)f(an)i Fr(AND)f
Ft(operation.)32 b(This)198 3283 y(node)14 b(has)g(two)f(successors)i
(called)e Fr(lexpr)h Ft(and)f Fr(rexpr)h Ft(pointing)e(to)i(two)f
Fp(subtr)n(ees)p Ft(.)21 b(The)14 b Fp(subtr)n(ee)198
3342 y Ft(attached)g(to)f Fr(lexpr)g Ft(represents)h(the)g
(quali\002cation)e Fk(s:sno)17 b(>)f Fl(2)e Ft(and)f(the)h(one)f
(attached)h(to)g Fr(rexpr)198 3402 y Ft(represents)f
Fk(s:sno)i Fl(=)f Fk(se:sno)p Ft(.)j(F)o(or)c(e)o(v)o(ery)f
Fp(attrib)o(ute)g Ft(an)h Fr(Attr)f Ft(node)h(is)g(created)g(holding)e
(the)i(name)p eop
%%Page: 54 54
54 53 bop 270 60 a Ft(54)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(of)j(the)f Fp(r)n(elation)h Ft(and)g(a)g(pointer)g(to)f(a)i
Fr(Value)e Ft(node)h(holding)f(the)h(name)g(of)g(the)f
Fp(attrib)o(ute)p Ft(.)24 b(F)o(or)14 b(the)270 294 y
Fp(constant)e Ft(appearing)g(in)g(the)h(query)f(a)g Fr(Const)g
Ft(node)g(is)h(created)f(holding)g(the)g(v)o(alue.)363
2301 y @beginspecial 144 @llx 201 @lly 467 @urx 590 @ury
3230 @rwi @setspecial
%%BeginDocument: figures/parsetree.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
131.5 603.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1215 450 m 1485 720 l gs col-1 s gr 
% Polyline
n 1485 450 m 1215 720 l gs col-1 s gr 
% Polyline
n 1215 1800 m 1485 2070 l gs col-1 s gr 
% Polyline
n 1485 1800 m 1215 2070 l gs col-1 s gr 
% Polyline
n 1215 2070 m 1485 2340 l gs col-1 s gr 
% Polyline
n 1485 2070 m 1215 2340 l gs col-1 s gr 
% Polyline
n 1215 2340 m 1485 2610 l gs col-1 s gr 
% Polyline
n 1485 2340 m 1215 2610 l gs col-1 s gr 
% Polyline
n 2430 450 m 3240 450 l gs col-1 s gr 
% Polyline
n 2430 225 m 3240 225 l 3240 720 l 2430 720 l cp gs col-1 s gr 
% Polyline
n 2970 450 m 2970 720 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2520 630 m
gs 1 -1 sc (val) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 405 m
gs 1 -1 sc (ResTarget) col-1 sh gr
% Polyline
n 3510 450 m 4410 450 l gs col-1 s gr 
% Polyline
n 3510 720 m 4410 720 l gs col-1 s gr 
% Polyline
n 3510 225 m 4410 225 l 4410 990 l 3510 990 l cp gs col-1 s gr 
% Polyline
n 4140 450 m 4140 990 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3825 405 m
gs 1 -1 sc (Attr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 900 m
gs 1 -1 sc (attrs) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 630 m
gs 1 -1 sc (relname) col-1 sh gr
% Polyline
n 4635 720 m 5175 720 l 5175 990 l 4635 990 l cp gs col-1 s gr 
% Polyline
n 4905 720 m 4905 990 l gs col-1 s gr 
% Polyline
n 4905 720 m 5175 990 l gs col-1 s gr 
% Polyline
n 5175 720 m 4905 990 l gs col-1 s gr 
% Polyline
n 4365 1215 m 5175 1215 l 5175 1710 l 4365 1710 l cp gs col-1 s gr 
% Polyline
n 4365 1440 m 5175 1440 l gs col-1 s gr 
% Polyline
n 4905 1440 m 4905 1710 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4590 1395 m
gs 1 -1 sc (Value) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4455 1620 m
gs 1 -1 sc (val.str) col-1 sh gr
% Polyline
n 2430 5265 m 3330 5265 l gs col-1 s gr 
% Polyline
n 2430 5535 m 3330 5535 l gs col-1 s gr 
% Polyline
n 2430 5040 m 3330 5040 l 3330 5805 l 2430 5805 l cp gs col-1 s gr 
% Polyline
n 3060 5265 m 3060 5805 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2520 5715 m
gs 1 -1 sc (relExpr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 5445 m
gs 1 -1 sc (name) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 5220 m
gs 1 -1 sc (RangeVar) col-1 sh gr
% Polyline
n 3600 5670 m 4500 5670 l gs col-1 s gr 
% Polyline
n 3600 5445 m 4500 5445 l 4500 5940 l 3600 5940 l cp gs col-1 s gr 
% Polyline
n 4230 5670 m 4230 5940 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3690 5850 m
gs 1 -1 sc (relname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3690 5625 m
gs 1 -1 sc (RelExpr) col-1 sh gr
% Polyline
gs  clippath
3453 5640 m 3573 5670 l 3453 5700 l 3615 5700 l 3615 5640 l  cp clip
n 3195 5670 m 3600 5670 l gs col-1 s gr gr

% arrowhead
n 3453 5640 m 3573 5670 l 3453 5700 l 3453 5670 l 3453 5640 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4395 6018 m 4365 6138 l 4335 6018 l 4335 6180 l 4395 6180 l  cp clip
n 4365 5805 m 4365 6165 l gs col-1 s gr gr

% arrowhead
n 4395 6018 m 4365 6138 l 4335 6018 l 4365 6018 l 4395 6018 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3588 5190 m 3708 5220 l 3588 5250 l 3750 5250 l 3750 5190 l  cp clip
n 3240.0 5400.0 m 3375.0 5400.0 l
	3375.0 5400.0 3510.0 5400.0 3510.0 5310.0 DrawSplineSection
	3510.0 5310.0 3510.0 5220.0 3622.5 5220.0 DrawSplineSection
	3735.0 5220.0 l  gs col-1 s gr
 gr

% arrowhead
n 3588 5190 m 3708 5220 l 3588 5250 l 3588 5220 l 3588 5190 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
3825 5265 m
gs 1 -1 sc ("se") col-1 sh gr
/Times-Roman ff 150.00 scf sf
4185 6345 m
gs 1 -1 sc ("sells") col-1 sh gr
% Polyline
n 1935 855 m 1935 315 l 2205 315 l 2205 855 l cp gs col-1 s gr 
% Polyline
n 1935 585 m 2205 585 l gs col-1 s gr 
% Polyline
n 2205 2115 m 2205 2655 l 1935 2655 l 1935 2115 l cp gs col-1 s gr 
% Polyline
n 2205 2385 m 1935 2385 l gs col-1 s gr 
% Polyline
n 2205 2385 m 1935 2655 l gs col-1 s gr 
% Polyline
n 2205 2655 m 1935 2385 l gs col-1 s gr 
% Polyline
gs  clippath
2283 420 m 2403 450 l 2283 480 l 2445 480 l 2445 420 l  cp clip
n 2070 450 m 2430 450 l gs col-1 s gr gr

% arrowhead
n 2283 420 m 2403 450 l 2283 480 l 2283 450 l 2283 420 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2283 2220 m 2403 2250 l 2283 2280 l 2445 2280 l 2445 2220 l  cp clip
n 2070 2250 m 2430 2250 l gs col-1 s gr gr

% arrowhead
n 2283 2220 m 2403 2250 l 2283 2280 l 2283 2250 l 2283 2220 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2100 1968 m 2070 2088 l 2040 1968 l 2040 2130 l 2100 2130 l  cp clip
n 2070 720 m 2070 2115 l gs col-1 s gr gr

% arrowhead
n 2100 1968 m 2070 2088 l 2040 1968 l 2070 1968 l 2100 1968 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1935 4455 m 1935 3915 l 2205 3915 l 2205 4455 l cp gs col-1 s gr 
% Polyline
n 1935 4185 m 2205 4185 l gs col-1 s gr 
% Polyline
n 2205 5265 m 2205 5805 l 1935 5805 l 1935 5265 l cp gs col-1 s gr 
% Polyline
n 2205 5535 m 1935 5535 l gs col-1 s gr 
% Polyline
n 2205 5535 m 1935 5805 l gs col-1 s gr 
% Polyline
n 2205 5805 m 1935 5535 l gs col-1 s gr 
% Polyline
n 2430 3915 m 3330 3915 l gs col-1 s gr 
% Polyline
n 2430 4185 m 3330 4185 l gs col-1 s gr 
% Polyline
n 2430 3690 m 3330 3690 l 3330 4455 l 2430 4455 l cp gs col-1 s gr 
% Polyline
n 3060 3915 m 3060 4455 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2520 4365 m
gs 1 -1 sc (relExpr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 4095 m
gs 1 -1 sc (name) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 3870 m
gs 1 -1 sc (RangeVar) col-1 sh gr
% Polyline
n 3600 4320 m 4500 4320 l gs col-1 s gr 
% Polyline
n 3600 4095 m 4500 4095 l 4500 4590 l 3600 4590 l cp gs col-1 s gr 
% Polyline
n 4230 4320 m 4230 4590 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3690 4500 m
gs 1 -1 sc (relname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3690 4275 m
gs 1 -1 sc (RelExpr) col-1 sh gr
% Polyline
n 2430 2250 m 3240 2250 l gs col-1 s gr 
% Polyline
n 2430 2025 m 3240 2025 l 3240 2520 l 2430 2520 l cp gs col-1 s gr 
% Polyline
n 2970 2250 m 2970 2520 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2520 2430 m
gs 1 -1 sc (val) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 2205 m
gs 1 -1 sc (ResTarget) col-1 sh gr
% Polyline
n 3510 2250 m 4410 2250 l gs col-1 s gr 
% Polyline
n 3510 2520 m 4410 2520 l gs col-1 s gr 
% Polyline
n 3510 2025 m 4410 2025 l 4410 2790 l 3510 2790 l cp gs col-1 s gr 
% Polyline
n 4140 2250 m 4140 2790 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3825 2205 m
gs 1 -1 sc (Attr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 2700 m
gs 1 -1 sc (attrs) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 2430 m
gs 1 -1 sc (relname) col-1 sh gr
% Polyline
n 4635 2520 m 5175 2520 l 5175 2790 l 4635 2790 l cp gs col-1 s gr 
% Polyline
n 4905 2520 m 4905 2790 l gs col-1 s gr 
% Polyline
n 4905 2520 m 5175 2790 l gs col-1 s gr 
% Polyline
n 5175 2520 m 4905 2790 l gs col-1 s gr 
% Polyline
n 4365 3015 m 5175 3015 l 5175 3510 l 4365 3510 l cp gs col-1 s gr 
% Polyline
n 4365 3240 m 5175 3240 l gs col-1 s gr 
% Polyline
n 4905 3240 m 4905 3510 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4590 3195 m
gs 1 -1 sc (Value) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4455 3420 m
gs 1 -1 sc (val.str) col-1 sh gr
% Polyline
n 225 450 m 1485 450 l gs col-1 s gr 
% Polyline
n 1215 990 m 1215 2610 l gs col-1 s gr 
% Polyline
n 225 720 m 1485 720 l gs col-1 s gr 
% Polyline
n 225 990 m 1485 990 l gs col-1 s gr 
% Polyline
n 225 1260 m 1485 1260 l gs col-1 s gr 
% Polyline
n 225 1530 m 1485 1530 l gs col-1 s gr 
% Polyline
n 225 1800 m 1485 1800 l gs col-1 s gr 
% Polyline
n 225 2070 m 1485 2070 l gs col-1 s gr 
% Polyline
n 225 225 m 1485 225 l 1485 2610 l 225 2610 l cp gs col-1 s gr 
% Polyline
n 225 2340 m 1485 2340 l gs col-1 s gr 
% Polyline
n 1215 450 m 1215 720 l gs col-1 s gr 
% Polyline
gs  clippath
3363 555 m 3483 585 l 3363 615 l 3525 615 l 3525 555 l  cp clip
n 3105 585 m 3510 585 l gs col-1 s gr gr

% arrowhead
n 3363 555 m 3483 585 l 3363 615 l 3363 585 l 3363 555 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4488 555 m 4608 585 l 4488 615 l 4650 615 l 4650 555 l  cp clip
n 4275 585 m 4635 585 l gs col-1 s gr gr

% arrowhead
n 4488 555 m 4608 585 l 4488 615 l 4488 585 l 4488 555 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4488 825 m 4608 855 l 4488 885 l 4650 885 l 4650 825 l  cp clip
n 4275 855 m 4635 855 l gs col-1 s gr gr

% arrowhead
n 4488 825 m 4608 855 l 4488 885 l 4488 855 l 4488 825 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4800 1068 m 4770 1188 l 4740 1068 l 4740 1230 l 4800 1230 l  cp clip
n 4770 855 m 4770 1215 l gs col-1 s gr gr

% arrowhead
n 4800 1068 m 4770 1188 l 4740 1068 l 4770 1068 l 4800 1068 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
5070 1788 m 5040 1908 l 5010 1788 l 5010 1950 l 5070 1950 l  cp clip
n 5040 1575 m 5040 1935 l gs col-1 s gr gr

% arrowhead
n 5070 1788 m 5040 1908 l 5010 1788 l 5040 1788 l 5070 1788 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2283 4020 m 2403 4050 l 2283 4080 l 2445 4080 l 2445 4020 l  cp clip
n 2070 4050 m 2430 4050 l gs col-1 s gr gr

% arrowhead
n 2283 4020 m 2403 4050 l 2283 4080 l 2283 4050 l 2283 4020 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2100 5118 m 2070 5238 l 2040 5118 l 2040 5280 l 2100 5280 l  cp clip
n 2070 4320 m 2070 5265 l gs col-1 s gr gr

% arrowhead
n 2100 5118 m 2070 5238 l 2040 5118 l 2070 5118 l 2100 5118 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2283 5370 m 2403 5400 l 2283 5430 l 2445 5430 l 2445 5370 l  cp clip
n 2070 5400 m 2430 5400 l gs col-1 s gr gr

% arrowhead
n 2283 5370 m 2403 5400 l 2283 5430 l 2283 5400 l 2283 5370 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3453 4290 m 3573 4320 l 3453 4350 l 3615 4350 l 3615 4290 l  cp clip
n 3195 4320 m 3600 4320 l gs col-1 s gr gr

% arrowhead
n 3453 4290 m 3573 4320 l 3453 4350 l 3453 4320 l 3453 4290 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4395 4668 m 4365 4788 l 4335 4668 l 4335 4830 l 4395 4830 l  cp clip
n 4365 4455 m 4365 4815 l gs col-1 s gr gr

% arrowhead
n 4395 4668 m 4365 4788 l 4335 4668 l 4365 4668 l 4395 4668 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3363 2355 m 3483 2385 l 3363 2415 l 3525 2415 l 3525 2355 l  cp clip
n 3105 2385 m 3510 2385 l gs col-1 s gr gr

% arrowhead
n 3363 2355 m 3483 2385 l 3363 2415 l 3363 2385 l 3363 2355 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4488 2355 m 4608 2385 l 4488 2415 l 4650 2415 l 4650 2355 l  cp clip
n 4275 2385 m 4635 2385 l gs col-1 s gr gr

% arrowhead
n 4488 2355 m 4608 2385 l 4488 2415 l 4488 2385 l 4488 2355 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4488 2625 m 4608 2655 l 4488 2685 l 4650 2685 l 4650 2625 l  cp clip
n 4275 2655 m 4635 2655 l gs col-1 s gr gr

% arrowhead
n 4488 2625 m 4608 2655 l 4488 2685 l 4488 2655 l 4488 2625 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4800 2868 m 4770 2988 l 4740 2868 l 4740 3030 l 4800 3030 l  cp clip
n 4770 2655 m 4770 3015 l gs col-1 s gr gr

% arrowhead
n 4800 2868 m 4770 2988 l 4740 2868 l 4770 2868 l 4800 2868 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
5070 3588 m 5040 3708 l 5010 3588 l 5010 3750 l 5070 3750 l  cp clip
n 5040 3375 m 5040 3735 l gs col-1 s gr gr

% arrowhead
n 5070 3588 m 5040 3708 l 5010 3588 l 5040 3588 l 5070 3588 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1788 555 m 1908 585 l 1788 615 l 1950 615 l 1950 555 l  cp clip
n 1350.0 1125.0 m 1530.0 1125.0 l
	1530.0 1125.0 1710.0 1125.0 1687.5 855.0 DrawSplineSection
	1687.5 855.0 1665.0 585.0 1800.0 585.0 DrawSplineSection
	1935.0 585.0 l  gs col-1 s gr
 gr

% arrowhead
n 1788 555 m 1908 585 l 1788 615 l 1788 585 l 1788 555 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2100 3768 m 2070 3888 l 2040 3768 l 2040 3930 l 2100 3930 l  cp clip
n 1350.0 1395.0 m 1620.0 1395.0 l
	1620.0 1395.0 1890.0 1395.0 1845.0 2272.5 DrawSplineSection
	1845.0 2272.5 1800.0 3150.0 1935.0 3285.0 DrawSplineSection
	1935.0 3285.0 2070.0 3420.0 2070.0 3667.5 DrawSplineSection
	2070.0 3915.0 l  gs col-1 s gr
 gr

% arrowhead
n 2100 3768 m 2070 3888 l 2040 3768 l 2070 3768 l 2100 3768 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1155 3228 m 1125 3348 l 1095 3228 l 1095 3390 l 1155 3390 l  cp clip
n 1350.0 1665.0 m 1507.5 1665.0 l
	1507.5 1665.0 1665.0 1665.0 1665.0 2340.0 DrawSplineSection
	1665.0 2340.0 1665.0 3015.0 1395.0 3015.0 DrawSplineSection
	1395.0 3015.0 1125.0 3015.0 1125.0 3195.0 DrawSplineSection
	1125.0 3375.0 l  gs col-1 s gr
 gr

% arrowhead
n 1155 3228 m 1125 3348 l 1095 3228 l 1125 3228 l 1155 3228 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3543 3840 m 3663 3870 l 3543 3900 l 3705 3900 l 3705 3840 l  cp clip
n 3195.0 4050.0 m 3330.0 4050.0 l
	3330.0 4050.0 3465.0 4050.0 3465.0 3960.0 DrawSplineSection
	3465.0 3960.0 3465.0 3870.0 3577.5 3870.0 DrawSplineSection
	3690.0 3870.0 l  gs col-1 s gr
 gr

% arrowhead
n 3543 3840 m 3663 3870 l 3543 3900 l 3543 3870 l 3543 3840 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
315 900 m
gs 1 -1 sc (unionall:      false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 405 m
gs 1 -1 sc (SelectStmt) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 630 m
gs 1 -1 sc (unique) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1170 m
gs 1 -1 sc (targetList) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1440 m
gs 1 -1 sc (fromClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1710 m
gs 1 -1 sc (whereClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1980 m
gs 1 -1 sc (groupClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 2250 m
gs 1 -1 sc (havingClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 2520 m
gs 1 -1 sc (sortClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4815 2115 m
gs 1 -1 sc ("sname") col-1 sh gr
/Times-Roman ff 150.00 scf sf
4725 630 m
gs 1 -1 sc ("s") col-1 sh gr
/Times-Roman ff 150.00 scf sf
720 3600 m
gs 1 -1 sc (Operator Tree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
765 3795 m
gs 1 -1 sc (representing ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
630 3990 m
gs 1 -1 sc (the qualifications) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3780 3915 m
gs 1 -1 sc ("s") col-1 sh gr
/Times-Roman ff 150.00 scf sf
4095 4995 m
gs 1 -1 sc ("supplier") col-1 sh gr
/Times-Roman ff 150.00 scf sf
4725 2430 m
gs 1 -1 sc ("se") col-1 sh gr
/Times-Roman ff 150.00 scf sf
4905 3915 m
gs 1 -1 sc ("sno") col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 561 2411 a(Figure)g(3.2:)j Fp(T)-5 b(ar)n(getList)12
b Ft(and)h Fp(F)m(r)n(omList)g Ft(for)e(query)h(of)g(e)o(xample)h(3.1)
270 2651 y Fh(3.3.2)59 b(T)l(ransf)o(ormation)13 b(Pr)o(ocess)270
2745 y Ft(The)18 b Fp(tr)o(ansformation)f(pr)n(ocess)i
Ft(takes)e(the)g Fp(tr)n(ee)h Ft(handed)f(back)g(by)h(the)f
Fp(parser)h Ft(as)f(input)g(and)g(steps)270 2804 y(recursi)o(v)o(ely)g
(through)f(it.)31 b(If)17 b(a)h Fr(SelectStmt)e Ft(node)i(is)g(found,)g
(it)f(is)h(transformed)f(to)g(a)h Fr(Query)270 2864 y
Ft(node)g(which)g(will)g(be)g(the)h(top)f(most)g(node)g(of)g(the)g(ne)o
(w)g(data)h(structure.)32 b(Figure)18 b(3.4)g(sho)o(ws)h(the)270
2924 y(transformed)12 b(data)h(structure)f(\(the)g(part)h(for)f(the)g
(transformed)g Fp(wher)n(e)i(clause)f Ft(is)g(gi)o(v)o(en)g(in)g
(\002gure)f(3.5)270 2984 y(because)h(there)f(was)h(not)f(enough)g
(space)h(to)f(sho)o(w)g(all)h(parts)f(in)g(one)h(\002gure\).)345
3044 y(No)o(w)i(a)i(check)f(is)g(made,)i(if)d(the)h Fp(r)n(elation)g
(names)g Ft(in)g(the)g Fp(fr)n(omClause)h Ft(are)e(kno)o(wn)h(to)g(the)
g(sys-)270 3103 y(tem.)21 b(F)o(or)14 b(e)o(v)o(ery)f
Fp(r)n(elation)h(name)h Ft(that)e(is)i(present)f(in)g(the)g
Fp(system)h(catalogs)f Ft(a)g Fr(RTE)g Ft(node)g(is)g(created)270
3163 y(containing)e(the)g Fp(r)n(elation)g(name)p Ft(,)h(the)f
Fp(alias)g(name)g Ft(and)h(the)f Fp(r)n(elation)g(id)p
Ft(.)k(From)11 b(no)o(w)h(on)g(the)g Fp(r)n(elation)270
3223 y(ids)h Ft(are)g(used)h(to)f(refer)f(to)h(the)g
Fp(r)n(elations)g Ft(gi)o(v)o(en)g(in)g(the)g(query)m(.)k(All)c
Fr(RTE)g Ft(nodes)g(are)g(collected)g(in)g(the)270 3283
y Fp(r)o(ange)k(table)f(entry)h(list)g Ft(which)g(is)g(connected)g(to)f
(the)h(\002eld)f Fr(rtable)h Ft(of)f(the)h Fr(Query)f
Ft(node.)29 b(If)16 b(a)270 3342 y(name)d(of)f(a)i Fp(r)n(elation)f
Ft(that)f(is)i(not)e(kno)o(wn)h(to)g(the)g(system)g(is)g(detected)g(in)
g(the)g(query)f(an)i(error)d(will)i(be)270 3402 y(returned)e(and)i(the)
f Fp(query)h(pr)n(ocessing)g Ft(will)f(be)h(aborted.)p
eop
%%Page: 55 55
55 54 bop 198 60 a Fm(3.3.)29 b(THE)13 b(P)-5 b(ARSER)13
b(ST)-5 b(A)n(GE)1189 b Ft(55)276 2863 y @beginspecial
141 @llx 165 @lly 470 @urx 627 @ury 3290 @rwi @setspecial
%%BeginDocument: figures/where_clause.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
128.5 640.0 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1215 450 m 1485 720 l gs col-1 s gr 
% Polyline
n 1485 450 m 1215 720 l gs col-1 s gr 
% Polyline
n 1215 1800 m 1485 2070 l gs col-1 s gr 
% Polyline
n 1485 1800 m 1215 2070 l gs col-1 s gr 
% Polyline
n 1215 2070 m 1485 2340 l gs col-1 s gr 
% Polyline
n 1485 2070 m 1215 2340 l gs col-1 s gr 
% Polyline
n 1215 2340 m 1485 2610 l gs col-1 s gr 
% Polyline
n 1485 2340 m 1215 2610 l gs col-1 s gr 
% Polyline
n 2790 1260 m 1800 1260 l gs col-1 s gr 
% Polyline
n 1800 1530 m 2790 1530 l gs col-1 s gr 
% Polyline
n 1800 1800 m 2790 1800 l gs col-1 s gr 
% Polyline
n 1800 2070 m 2790 2070 l gs col-1 s gr 
% Polyline
n 1800 1035 m 2790 1035 l 2790 2340 l 1800 2340 l cp gs col-1 s gr 
% Polyline
n 2520 1800 m 2520 2340 l gs col-1 s gr 
% Polyline
n 2520 1260 m 2520 1530 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2070 1215 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 1710 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 1440 m
gs 1 -1 sc (opname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 1980 m
gs 1 -1 sc (rexpr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 2250 m
gs 1 -1 sc (lexpr) col-1 sh gr
% Polyline
n 2520 1260 m 2790 1530 l gs col-1 s gr 
% Polyline
n 2790 1260 m 2520 1530 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2385 1710 m
gs 1 -1 sc (AND) col-1 sh gr
% Polyline
n 1350 6120 m 1890 6120 l 1890 6390 l 1350 6390 l cp gs col-1 s gr 
% Polyline
n 1620 6120 m 1620 6390 l gs col-1 s gr 
% Polyline
n 1620 6120 m 1890 6390 l gs col-1 s gr 
% Polyline
n 1890 6120 m 1620 6390 l gs col-1 s gr 
% Polyline
n 1080 6615 m 1890 6615 l 1890 7110 l 1080 7110 l cp gs col-1 s gr 
% Polyline
n 1080 6840 m 1890 6840 l gs col-1 s gr 
% Polyline
n 1620 6840 m 1620 7110 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1305 6795 m
gs 1 -1 sc (Value) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1170 7020 m
gs 1 -1 sc (val.str) col-1 sh gr
% Polyline
n 225 5850 m 1125 5850 l gs col-1 s gr 
% Polyline
n 225 6120 m 1125 6120 l gs col-1 s gr 
% Polyline
n 225 5625 m 1125 5625 l 1125 6390 l 225 6390 l cp gs col-1 s gr 
% Polyline
n 855 5850 m 855 6390 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
540 5805 m
gs 1 -1 sc (Attr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 6300 m
gs 1 -1 sc (attrs) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 6030 m
gs 1 -1 sc (relname) col-1 sh gr
% Polyline
gs  clippath
1785 7188 m 1755 7308 l 1725 7188 l 1725 7350 l 1785 7350 l  cp clip
n 1755 6975 m 1755 7335 l gs col-1 s gr gr

% arrowhead
n 1785 7188 m 1755 7308 l 1725 7188 l 1755 7188 l 1785 7188 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1203 5955 m 1323 5985 l 1203 6015 l 1365 6015 l 1365 5955 l  cp clip
n 990 5985 m 1350 5985 l gs col-1 s gr gr

% arrowhead
n 1203 5955 m 1323 5985 l 1203 6015 l 1203 5985 l 1203 5955 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1203 6225 m 1323 6255 l 1203 6285 l 1365 6285 l 1365 6225 l  cp clip
n 990 6255 m 1350 6255 l gs col-1 s gr gr

% arrowhead
n 1203 6225 m 1323 6255 l 1203 6285 l 1203 6255 l 1203 6225 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1515 6468 m 1485 6588 l 1455 6468 l 1455 6630 l 1515 6630 l  cp clip
n 1485 6255 m 1485 6615 l gs col-1 s gr gr

% arrowhead
n 1515 6468 m 1485 6588 l 1455 6468 l 1485 6468 l 1515 6468 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
1620 7515 m
gs 1 -1 sc ("sno") col-1 sh gr
/Times-Roman ff 150.00 scf sf
1440 6030 m
gs 1 -1 sc ("s") col-1 sh gr
% Polyline
n 1350 5130 m 2340 5130 l gs col-1 s gr 
% Polyline
n 1350 4905 m 2340 4905 l 2340 5400 l 1350 5400 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1440 5310 m
gs 1 -1 sc (val.val.ival:  2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 5085 m
gs 1 -1 sc (A_Const) col-1 sh gr
% Polyline
n 2475 5850 m 3375 5850 l gs col-1 s gr 
% Polyline
n 2475 6120 m 3375 6120 l gs col-1 s gr 
% Polyline
n 2475 5625 m 3375 5625 l 3375 6390 l 2475 6390 l cp gs col-1 s gr 
% Polyline
n 3105 5850 m 3105 6390 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2790 5805 m
gs 1 -1 sc (Attr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 6300 m
gs 1 -1 sc (attrs) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 6030 m
gs 1 -1 sc (relname) col-1 sh gr
% Polyline
n 3600 6120 m 4140 6120 l 4140 6390 l 3600 6390 l cp gs col-1 s gr 
% Polyline
n 3870 6120 m 3870 6390 l gs col-1 s gr 
% Polyline
n 3870 6120 m 4140 6390 l gs col-1 s gr 
% Polyline
n 4140 6120 m 3870 6390 l gs col-1 s gr 
% Polyline
n 3330 6615 m 4140 6615 l 4140 7110 l 3330 7110 l cp gs col-1 s gr 
% Polyline
n 3330 6840 m 4140 6840 l gs col-1 s gr 
% Polyline
n 3870 6840 m 3870 7110 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3555 6795 m
gs 1 -1 sc (Value) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3420 7020 m
gs 1 -1 sc (val.str) col-1 sh gr
% Polyline
gs  clippath
3453 5955 m 3573 5985 l 3453 6015 l 3615 6015 l 3615 5955 l  cp clip
n 3240 5985 m 3600 5985 l gs col-1 s gr gr

% arrowhead
n 3453 5955 m 3573 5985 l 3453 6015 l 3453 5985 l 3453 5955 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3453 6225 m 3573 6255 l 3453 6285 l 3615 6285 l 3615 6225 l  cp clip
n 3240 6255 m 3600 6255 l gs col-1 s gr gr

% arrowhead
n 3453 6225 m 3573 6255 l 3453 6285 l 3453 6255 l 3453 6225 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3765 6468 m 3735 6588 l 3705 6468 l 3705 6630 l 3765 6630 l  cp clip
n 3735 6255 m 3735 6615 l gs col-1 s gr gr

% arrowhead
n 3765 6468 m 3735 6588 l 3705 6468 l 3735 6468 l 3765 6468 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4035 7188 m 4005 7308 l 3975 7188 l 3975 7350 l 4035 7350 l  cp clip
n 4005 6975 m 4005 7335 l gs col-1 s gr gr

% arrowhead
n 4035 7188 m 4005 7308 l 3975 7188 l 4005 7188 l 4035 7188 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
3690 6030 m
gs 1 -1 sc ("s") col-1 sh gr
/Times-Roman ff 150.00 scf sf
3870 7515 m
gs 1 -1 sc ("sno") col-1 sh gr
% Polyline
n 3690 5130 m 4590 5130 l gs col-1 s gr 
% Polyline
n 3690 5400 m 4590 5400 l gs col-1 s gr 
% Polyline
n 3690 4905 m 4590 4905 l 4590 5670 l 3690 5670 l cp gs col-1 s gr 
% Polyline
n 4320 5130 m 4320 5670 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4005 5085 m
gs 1 -1 sc (Attr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3780 5580 m
gs 1 -1 sc (attrs) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3780 5310 m
gs 1 -1 sc (relname) col-1 sh gr
% Polyline
n 4815 5400 m 5355 5400 l 5355 5670 l 4815 5670 l cp gs col-1 s gr 
% Polyline
n 5085 5400 m 5085 5670 l gs col-1 s gr 
% Polyline
n 5085 5400 m 5355 5670 l gs col-1 s gr 
% Polyline
n 5355 5400 m 5085 5670 l gs col-1 s gr 
% Polyline
n 4545 5895 m 5355 5895 l 5355 6390 l 4545 6390 l cp gs col-1 s gr 
% Polyline
n 4545 6120 m 5355 6120 l gs col-1 s gr 
% Polyline
n 5085 6120 m 5085 6390 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4770 6075 m
gs 1 -1 sc (Value) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4635 6300 m
gs 1 -1 sc (val.str) col-1 sh gr
% Polyline
gs  clippath
4668 5235 m 4788 5265 l 4668 5295 l 4830 5295 l 4830 5235 l  cp clip
n 4455 5265 m 4815 5265 l gs col-1 s gr gr

% arrowhead
n 4668 5235 m 4788 5265 l 4668 5295 l 4668 5265 l 4668 5235 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4668 5505 m 4788 5535 l 4668 5565 l 4830 5565 l 4830 5505 l  cp clip
n 4455 5535 m 4815 5535 l gs col-1 s gr gr

% arrowhead
n 4668 5505 m 4788 5535 l 4668 5565 l 4668 5535 l 4668 5505 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4980 5748 m 4950 5868 l 4920 5748 l 4920 5910 l 4980 5910 l  cp clip
n 4950 5535 m 4950 5895 l gs col-1 s gr gr

% arrowhead
n 4980 5748 m 4950 5868 l 4920 5748 l 4950 5748 l 4980 5748 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
5250 6468 m 5220 6588 l 5190 6468 l 5190 6630 l 5250 6630 l  cp clip
n 5220 6255 m 5220 6615 l gs col-1 s gr gr

% arrowhead
n 5250 6468 m 5220 6588 l 5190 6468 l 5220 6468 l 5250 6468 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
4905 5310 m
gs 1 -1 sc ("se") col-1 sh gr
/Times-Roman ff 150.00 scf sf
5085 6795 m
gs 1 -1 sc ("sno") col-1 sh gr
% Polyline
n 3465 3375 m 2475 3375 l gs col-1 s gr 
% Polyline
n 2475 3645 m 3465 3645 l gs col-1 s gr 
% Polyline
n 2475 3915 m 3465 3915 l gs col-1 s gr 
% Polyline
n 2475 4185 m 3465 4185 l gs col-1 s gr 
% Polyline
n 2475 3150 m 3465 3150 l 3465 4455 l 2475 4455 l cp gs col-1 s gr 
% Polyline
n 3195 3915 m 3195 4455 l gs col-1 s gr 
% Polyline
n 3195 3375 m 3195 3645 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2745 3330 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 3825 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 3555 m
gs 1 -1 sc (opname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 4095 m
gs 1 -1 sc (rexpr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 4365 m
gs 1 -1 sc (lexpr) col-1 sh gr
% Polyline
n 225 450 m 1485 450 l gs col-1 s gr 
% Polyline
n 1215 990 m 1215 2610 l gs col-1 s gr 
% Polyline
n 225 720 m 1485 720 l gs col-1 s gr 
% Polyline
n 225 990 m 1485 990 l gs col-1 s gr 
% Polyline
n 225 1260 m 1485 1260 l gs col-1 s gr 
% Polyline
n 225 1530 m 1485 1530 l gs col-1 s gr 
% Polyline
n 225 1800 m 1485 1800 l gs col-1 s gr 
% Polyline
n 225 2070 m 1485 2070 l gs col-1 s gr 
% Polyline
n 225 225 m 1485 225 l 1485 2610 l 225 2610 l cp gs col-1 s gr 
% Polyline
n 225 2340 m 1485 2340 l gs col-1 s gr 
% Polyline
n 1215 450 m 1215 720 l gs col-1 s gr 
% Polyline
gs  clippath
1653 1635 m 1773 1665 l 1653 1695 l 1815 1695 l 1815 1635 l  cp clip
n 1350 1665 m 1800 1665 l gs col-1 s gr gr

% arrowhead
n 1653 1635 m 1773 1665 l 1653 1695 l 1653 1665 l 1653 1635 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1293 3480 m 1413 3510 l 1293 3540 l 1455 3540 l 1455 3480 l  cp clip
n 1080 3510 m 1440 3510 l gs col-1 s gr gr

% arrowhead
n 1293 3480 m 1413 3510 l 1293 3540 l 1293 3510 l 1293 3480 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1215 3375 m 225 3375 l gs col-1 s gr 
% Polyline
n 225 3645 m 1215 3645 l gs col-1 s gr 
% Polyline
n 225 3915 m 1215 3915 l gs col-1 s gr 
% Polyline
n 225 4185 m 1215 4185 l gs col-1 s gr 
% Polyline
n 225 3150 m 1215 3150 l 1215 4455 l 225 4455 l cp gs col-1 s gr 
% Polyline
n 945 3915 m 945 4455 l gs col-1 s gr 
% Polyline
n 945 3375 m 945 3645 l gs col-1 s gr 
% Polyline
gs  clippath
3543 3480 m 3663 3510 l 3543 3540 l 3705 3540 l 3705 3480 l  cp clip
n 3330 3510 m 3690 3510 l gs col-1 s gr gr

% arrowhead
n 3543 3480 m 3663 3510 l 3543 3540 l 3543 3510 l 3543 3480 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
705 5478 m 675 5598 l 645 5478 l 645 5640 l 705 5640 l  cp clip
n 1080.0 4320.0 m 1237.5 4320.0 l
	1237.5 4320.0 1395.0 4320.0 1395.0 4522.5 DrawSplineSection
	1395.0 4522.5 1395.0 4725.0 1035.0 4725.0 DrawSplineSection
	1035.0 4725.0 675.0 4725.0 675.0 5175.0 DrawSplineSection
	675.0 5625.0 l  gs col-1 s gr
 gr

% arrowhead
n 705 5478 m 675 5598 l 645 5478 l 675 5478 l 705 5478 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1875 4758 m 1845 4878 l 1815 4758 l 1815 4920 l 1875 4920 l  cp clip
n 1080.0 4050.0 m 1282.5 4050.0 l
	1282.5 4050.0 1485.0 4050.0 1665.0 4095.0 DrawSplineSection
	1665.0 4095.0 1845.0 4140.0 1845.0 4522.5 DrawSplineSection
	1845.0 4905.0 l  gs col-1 s gr
 gr

% arrowhead
n 1875 4758 m 1845 4878 l 1815 4758 l 1845 4758 l 1875 4758 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
823 3041 m 734 3127 l 772 3009 l 687 3147 l 737 3179 l  cp clip
n 2655.0 2205.0 m 2835.0 2205.0 l
	2835.0 2205.0 3015.0 2205.0 3015.0 2452.5 DrawSplineSection
	3015.0 2452.5 3015.0 2700.0 1980.0 2745.0 DrawSplineSection
	1980.0 2745.0 945.0 2790.0 832.5 2970.0 DrawSplineSection
	720.0 3150.0 l  gs col-1 s gr
 gr

% arrowhead
n 823 3041 m 734 3127 l 772 3009 l 798 3025 l 823 3041 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2955 5478 m 2925 5598 l 2895 5478 l 2895 5640 l 2955 5640 l  cp clip
n 3330.0 4320.0 m 3487.5 4320.0 l
	3487.5 4320.0 3645.0 4320.0 3645.0 4522.5 DrawSplineSection
	3645.0 4522.5 3645.0 4725.0 3285.0 4725.0 DrawSplineSection
	3285.0 4725.0 2925.0 4725.0 2925.0 5175.0 DrawSplineSection
	2925.0 5625.0 l  gs col-1 s gr
 gr

% arrowhead
n 2955 5478 m 2925 5598 l 2895 5478 l 2925 5478 l 2955 5478 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4170 4758 m 4140 4878 l 4110 4758 l 4110 4920 l 4170 4920 l  cp clip
n 3330.0 4050.0 m 3577.5 4050.0 l
	3577.5 4050.0 3825.0 4050.0 3982.5 4162.5 DrawSplineSection
	3982.5 4162.5 4140.0 4275.0 4140.0 4590.0 DrawSplineSection
	4140.0 4905.0 l  gs col-1 s gr
 gr

% arrowhead
n 4170 4758 m 4140 4878 l 4110 4758 l 4140 4758 l 4170 4758 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3000 3003 m 2970 3123 l 2940 3003 l 2940 3165 l 3000 3165 l  cp clip
n 2655.0 1935.0 m 3015.0 1935.0 l
	3015.0 1935.0 3375.0 1935.0 3375.0 2272.5 DrawSplineSection
	3375.0 2272.5 3375.0 2610.0 3172.5 2700.0 DrawSplineSection
	3172.5 2700.0 2970.0 2790.0 2970.0 2970.0 DrawSplineSection
	2970.0 3150.0 l  gs col-1 s gr
 gr

% arrowhead
n 3000 3003 m 2970 3123 l 2940 3003 l 2970 3003 l 3000 3003 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1833 375 m 1953 405 l 1833 435 l 1995 435 l 1995 375 l  cp clip
n 1350.0 1125.0 m 1485.0 1125.0 l
	1485.0 1125.0 1620.0 1125.0 1597.5 765.0 DrawSplineSection
	1597.5 765.0 1575.0 405.0 1777.5 405.0 DrawSplineSection
	1980.0 405.0 l  gs col-1 s gr
 gr

% arrowhead
n 1833 375 m 1953 405 l 1833 435 l 1833 405 l 1833 375 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1833 735 m 1953 765 l 1833 795 l 1995 795 l 1995 735 l  cp clip
n 1350.0 1395.0 m 1530.0 1395.0 l
	1530.0 1395.0 1710.0 1395.0 1687.5 1080.0 DrawSplineSection
	1687.5 1080.0 1665.0 765.0 1822.5 765.0 DrawSplineSection
	1980.0 765.0 l  gs col-1 s gr
 gr

% arrowhead
n 1833 735 m 1953 765 l 1833 795 l 1833 765 l 1833 735 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
315 900 m
gs 1 -1 sc (unionall:      false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 405 m
gs 1 -1 sc (SelectStmt) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 630 m
gs 1 -1 sc (unique) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1170 m
gs 1 -1 sc (targetList) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1440 m
gs 1 -1 sc (fromClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1710 m
gs 1 -1 sc (whereClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 1980 m
gs 1 -1 sc (groupClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 2250 m
gs 1 -1 sc (havingClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 2520 m
gs 1 -1 sc (sortClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2025 450 m
gs 1 -1 sc (TargetList) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2025 810 m
gs 1 -1 sc (FromList) col-1 sh gr
/Times-Roman ff 150.00 scf sf
900 3825 m
gs 1 -1 sc (OP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1485 3555 m
gs 1 -1 sc (">") col-1 sh gr
/Times-Roman ff 150.00 scf sf
495 3330 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 3825 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 3555 m
gs 1 -1 sc (opname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 4095 m
gs 1 -1 sc (rexpr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 4365 m
gs 1 -1 sc (lexpr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 3825 m
gs 1 -1 sc (OP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3735 3555 m
gs 1 -1 sc ("=") col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 595 2973 a(Figure)11 b(3.3:)16 b Fp(Wher)n(eClause)e
Ft(for)e(query)f(of)h(e)o(xample)h(3.1)p eop
%%Page: 56 56
56 55 bop 270 60 a Ft(56)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(Ne)o(xt)k(it)h(is)f(checked)g(if)g(the)g Fp(attrib)o(ute)g
(names)h Ft(used)g(are)f(contained)g(in)g(the)g Fp(r)n(elations)h
Ft(gi)o(v)o(en)f(in)g(the)270 294 y(query)m(.)39 b(F)o(or)19
b(e)o(v)o(ery)h Fp(attrib)o(ute)g Ft(that)g(is)h(found)e(a)i
Fr(TLE)f Ft(node)g(is)g(created)g(holding)g(a)g(pointer)g(to)g(a)270
354 y Fr(Resdom)13 b Ft(node)h(\(which)f(holds)h(the)g(name)g(of)f(the)
h(column\))f(and)h(a)g(pointer)f(to)h(a)g Fr(VAR)g Ft(node.)20
b(There)270 413 y(are)c(two)g(important)f(numbers)h(in)h(the)f
Fr(VAR)g Ft(node.)28 b(The)17 b(\002eld)f Fr(varno)g
Ft(gi)o(v)o(es)h(the)f(position)g(of)g(the)270 473 y
Fp(r)n(elation)h Ft(containing)f(the)h(current)f Fp(attrib)o(ute)h
Ft(in)f(the)h Fp(r)o(ange)g(table)g(entry)g(list)g Ft(created)g(abo)o
(v)o(e.)30 b(The)270 533 y(\002eld)14 b Fr(varattno)g
Ft(gi)o(v)o(es)h(the)f(position)h(of)f(the)g Fp(attrib)o(ute)h
Ft(within)f(the)g Fp(r)n(elation)p Ft(.)23 b(If)14 b(the)g(name)h(of)f
(an)270 593 y Fp(attrib)o(ute)c Ft(cannot)g(be)g(found)f(an)i(error)e
(will)g(be)i(returned)e(and)h(the)g Fp(query)g(pr)n(ocessing)h
Ft(will)f(be)g(aborted.)310 2392 y @beginspecial 134
@llx 230 @lly 478 @urx 561 @ury 3440 @rwi @setspecial
%%BeginDocument: figures/transform.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
107.0 574.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1530 5040 m 1800 5310 l gs col-1 s gr 
% Polyline
n 1800 5040 m 1530 5310 l gs col-1 s gr 
% Polyline
n 1530 4770 m 1800 5040 l gs col-1 s gr 
% Polyline
n 1800 4770 m 1530 5040 l gs col-1 s gr 
% Polyline
n 1530 3960 m 1800 4230 l gs col-1 s gr 
% Polyline
n 1800 3960 m 1530 4230 l gs col-1 s gr 
% Polyline
n 1530 3690 m 1800 3960 l gs col-1 s gr 
% Polyline
n 1800 3690 m 1530 3960 l gs col-1 s gr 
% Polyline
n 1530 2340 m 1800 2610 l gs col-1 s gr 
% Polyline
n 1800 2340 m 1530 2610 l gs col-1 s gr 
% Polyline
n 1530 1260 m 1800 1530 l gs col-1 s gr 
% Polyline
n 1800 1260 m 1530 1530 l gs col-1 s gr 
% Polyline
n 1530 720 m 1800 990 l gs col-1 s gr 
% Polyline
n 1800 720 m 1530 990 l gs col-1 s gr 
% Polyline
n 2250 945 m 3150 945 l gs col-1 s gr 
% Polyline
n 2250 1215 m 3150 1215 l gs col-1 s gr 
% Polyline
n 2250 1485 m 3150 1485 l gs col-1 s gr 
% Polyline
n 2250 720 m 3150 720 l 3150 1755 l 2250 1755 l cp gs col-1 s gr 
% Polyline
n 2880 945 m 2880 1485 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2340 1395 m
gs 1 -1 sc (refname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 900 m
gs 1 -1 sc (RTE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 1125 m
gs 1 -1 sc (relname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 1665 m
gs 1 -1 sc (relid: 18208) col-1 sh gr
% Polyline
n 2835 225 m 2835 495 l gs col-1 s gr 
% Polyline
n 2565 225 m 3105 225 l 3105 495 l 2565 495 l cp gs col-1 s gr 
% Polyline
n 4860 225 m 4860 495 l gs col-1 s gr 
% Polyline
n 4590 225 m 5130 225 l 5130 495 l 4590 495 l cp gs col-1 s gr 
% Polyline
n 4860 225 m 5130 495 l gs col-1 s gr 
% Polyline
n 5130 225 m 4860 495 l gs col-1 s gr 
% Polyline
gs  clippath
2730 573 m 2700 693 l 2670 573 l 2670 735 l 2730 735 l  cp clip
n 2700 360 m 2700 720 l gs col-1 s gr gr

% arrowhead
n 2730 573 m 2700 693 l 2670 573 l 2700 573 l 2730 573 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4443 330 m 4563 360 l 4443 390 l 4605 390 l 4605 330 l  cp clip
n 2970 360 m 4590 360 l gs col-1 s gr gr

% arrowhead
n 4443 330 m 4563 360 l 4443 390 l 4443 360 l 4443 330 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4755 573 m 4725 693 l 4695 573 l 4695 735 l 4755 735 l  cp clip
n 4725 360 m 4725 720 l gs col-1 s gr gr

% arrowhead
n 4755 573 m 4725 693 l 4695 573 l 4725 573 l 4755 573 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2250 2745 m 3150 2745 l gs col-1 s gr 
% Polyline
n 2250 3015 m 3150 3015 l gs col-1 s gr 
% Polyline
n 2250 2520 m 3150 2520 l 3150 3285 l 2250 3285 l cp gs col-1 s gr 
% Polyline
n 2880 2745 m 2880 3285 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2565 2700 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 2925 m
gs 1 -1 sc (resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 3195 m
gs 1 -1 sc (expr) col-1 sh gr
% Polyline
n 4275 2745 m 5175 2745 l gs col-1 s gr 
% Polyline
n 4275 3015 m 5175 3015 l gs col-1 s gr 
% Polyline
n 4275 2520 m 5175 2520 l 5175 3285 l 4275 3285 l cp gs col-1 s gr 
% Polyline
n 4905 2745 m 4905 3285 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4590 2700 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 2925 m
gs 1 -1 sc (resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 3195 m
gs 1 -1 sc (expr) col-1 sh gr
% Polyline
n 2835 2025 m 2835 2295 l gs col-1 s gr 
% Polyline
n 2565 2025 m 3105 2025 l 3105 2295 l 2565 2295 l cp gs col-1 s gr 
% Polyline
n 4860 2025 m 4860 2295 l gs col-1 s gr 
% Polyline
n 4590 2025 m 5130 2025 l 5130 2295 l 4590 2295 l cp gs col-1 s gr 
% Polyline
n 4860 2025 m 5130 2295 l gs col-1 s gr 
% Polyline
n 5130 2025 m 4860 2295 l gs col-1 s gr 
% Polyline
n 450 450 m 1800 450 l gs col-1 s gr 
% Polyline
n 450 720 m 1800 720 l gs col-1 s gr 
% Polyline
n 450 990 m 1800 990 l gs col-1 s gr 
% Polyline
n 450 1260 m 1800 1260 l gs col-1 s gr 
% Polyline
n 450 1530 m 1800 1530 l gs col-1 s gr 
% Polyline
n 450 1800 m 1800 1800 l gs col-1 s gr 
% Polyline
n 450 2070 m 1800 2070 l gs col-1 s gr 
% Polyline
n 450 2340 m 1800 2340 l gs col-1 s gr 
% Polyline
n 450 2610 m 1800 2610 l gs col-1 s gr 
% Polyline
n 450 2880 m 1800 2880 l gs col-1 s gr 
% Polyline
n 450 3150 m 1800 3150 l gs col-1 s gr 
% Polyline
n 450 3690 m 1800 3690 l gs col-1 s gr 
% Polyline
n 450 3960 m 1800 3960 l gs col-1 s gr 
% Polyline
n 450 4230 m 1800 4230 l gs col-1 s gr 
% Polyline
n 450 3420 m 1800 3420 l gs col-1 s gr 
% Polyline
n 450 4500 m 1800 4500 l gs col-1 s gr 
% Polyline
n 450 4770 m 1800 4770 l gs col-1 s gr 
% Polyline
n 450 5040 m 1800 5040 l gs col-1 s gr 
% Polyline
n 450 225 m 1800 225 l 1800 5310 l 450 5310 l cp gs col-1 s gr 
% Polyline
n 1530 4770 m 1530 5310 l gs col-1 s gr 
% Polyline
n 1530 4230 m 1530 2880 l gs col-1 s gr 
% Polyline
n 1530 2340 m 1530 2610 l gs col-1 s gr 
% Polyline
n 1530 720 m 1530 990 l gs col-1 s gr 
% Polyline
n 1530 1260 m 1530 1530 l gs col-1 s gr 
% Polyline
n 1530 2610 m 1530 2880 l gs col-1 s gr 
% Polyline
n 1530 2610 m 1800 2880 l gs col-1 s gr 
% Polyline
n 1800 2610 m 1530 2880 l gs col-1 s gr 
% Polyline
gs  clippath
3228 1050 m 3348 1080 l 3228 1110 l 3390 1110 l 3390 1050 l  cp clip
n 3015 1080 m 3375 1080 l gs col-1 s gr gr

% arrowhead
n 3228 1050 m 3348 1080 l 3228 1110 l 3228 1080 l 3228 1050 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3228 1320 m 3348 1350 l 3228 1380 l 3390 1380 l 3390 1320 l  cp clip
n 3015 1350 m 3375 1350 l gs col-1 s gr gr

% arrowhead
n 3228 1320 m 3348 1350 l 3228 1380 l 3228 1350 l 3228 1320 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
5253 1050 m 5373 1080 l 5253 1110 l 5415 1110 l 5415 1050 l  cp clip
n 5040 1080 m 5400 1080 l gs col-1 s gr gr

% arrowhead
n 5253 1050 m 5373 1080 l 5253 1110 l 5253 1080 l 5253 1050 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
5253 1320 m 5373 1350 l 5253 1380 l 5415 1380 l 5415 1320 l  cp clip
n 5040 1350 m 5400 1350 l gs col-1 s gr gr

% arrowhead
n 5253 1320 m 5373 1350 l 5253 1380 l 5253 1350 l 5253 1320 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 4275 945 m 5175 945 l gs col-1 s gr 
% Polyline
n 4275 1215 m 5175 1215 l gs col-1 s gr 
% Polyline
n 4275 1485 m 5175 1485 l gs col-1 s gr 
% Polyline
n 4275 720 m 5175 720 l 5175 1755 l 4275 1755 l cp gs col-1 s gr 
% Polyline
n 4905 945 m 4905 1485 l gs col-1 s gr 
% Polyline
gs  clippath
2730 2373 m 2700 2493 l 2670 2373 l 2670 2535 l 2730 2535 l  cp clip
n 2700 2160 m 2700 2520 l gs col-1 s gr gr

% arrowhead
n 2730 2373 m 2700 2493 l 2670 2373 l 2700 2373 l 2730 2373 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4443 2130 m 4563 2160 l 4443 2190 l 4605 2190 l 4605 2130 l  cp clip
n 2970 2160 m 4590 2160 l gs col-1 s gr gr

% arrowhead
n 4443 2130 m 4563 2160 l 4443 2190 l 4443 2160 l 4443 2130 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4755 2373 m 4725 2493 l 4695 2373 l 4695 2535 l 4755 2535 l  cp clip
n 4725 2160 m 4725 2520 l gs col-1 s gr gr

% arrowhead
n 4755 2373 m 4725 2493 l 4695 2373 l 4725 2373 l 4755 2373 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3228 4200 m 3348 4230 l 3228 4260 l 3390 4260 l 3390 4200 l  cp clip
n 3015 4230 m 3375 4230 l gs col-1 s gr gr

% arrowhead
n 3228 4200 m 3348 4230 l 3228 4260 l 3228 4230 l 3228 4200 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
5253 4200 m 5373 4230 l 5253 4260 l 5415 4260 l 5415 4200 l  cp clip
n 5040 4230 m 5400 4230 l gs col-1 s gr gr

% arrowhead
n 5253 4200 m 5373 4230 l 5253 4260 l 5253 4230 l 5253 4200 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2250 3825 m 3150 3825 l gs col-1 s gr 
% Polyline
n 2250 4095 m 3150 4095 l gs col-1 s gr 
% Polyline
n 2250 3600 m 3150 3600 l 3150 4365 l 2250 4365 l cp gs col-1 s gr 
% Polyline
n 2880 4095 m 2880 4365 l gs col-1 s gr 
% Polyline
n 4275 3825 m 5175 3825 l gs col-1 s gr 
% Polyline
n 4275 4095 m 5175 4095 l gs col-1 s gr 
% Polyline
n 4275 3600 m 5175 3600 l 5175 4365 l 4275 4365 l cp gs col-1 s gr 
% Polyline
n 4905 4095 m 4905 4365 l gs col-1 s gr 
% Polyline
n 2250 4905 m 3150 4905 l gs col-1 s gr 
% Polyline
n 2250 5175 m 3150 5175 l gs col-1 s gr 
% Polyline
n 4275 4905 m 5175 4905 l gs col-1 s gr 
% Polyline
n 4275 5175 m 5175 5175 l gs col-1 s gr 
% Polyline
n 2250 4680 m 3150 4680 l 3150 5445 l 2250 5445 l cp gs col-1 s gr 
% Polyline
n 4275 4680 m 5175 4680 l 5175 5445 l 4275 5445 l cp gs col-1 s gr 
% Open spline
gs  clippath
2825 3517 m 2719 3580 l 2783 3475 l 2668 3589 l 2711 3632 l  cp clip
n 3015.0 2880.0 m 3150.0 2880.0 l
	3150.0 2880.0 3285.0 2880.0 3285.0 2947.5 DrawSplineSection
	3285.0 2947.5 3285.0 3015.0 3285.0 3195.0 DrawSplineSection
	3285.0 3195.0 3285.0 3375.0 3105.0 3375.0 DrawSplineSection
	3105.0 3375.0 2925.0 3375.0 2812.5 3487.5 DrawSplineSection
	2700.0 3600.0 l  gs col-1 s gr
 gr

% arrowhead
n 2825 3517 m 2719 3580 l 2783 3475 l 2804 3496 l 2825 3517 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4850 3517 m 4744 3580 l 4808 3475 l 4693 3589 l 4736 3632 l  cp clip
n 5040.0 2880.0 m 5175.0 2880.0 l
	5175.0 2880.0 5310.0 2880.0 5310.0 2947.5 DrawSplineSection
	5310.0 2947.5 5310.0 3015.0 5310.0 3195.0 DrawSplineSection
	5310.0 3195.0 5310.0 3375.0 5130.0 3375.0 DrawSplineSection
	5130.0 3375.0 4950.0 3375.0 4837.5 3487.5 DrawSplineSection
	4725.0 3600.0 l  gs col-1 s gr
 gr

% arrowhead
n 4850 3517 m 4744 3580 l 4808 3475 l 4829 3496 l 4850 3517 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2418 330 m 2538 360 l 2418 390 l 2580 390 l 2580 330 l  cp clip
n 1665.0 3015.0 m 1800.0 3015.0 l
	1800.0 3015.0 1935.0 3015.0 1935.0 2902.5 DrawSplineSection
	1935.0 2902.5 1935.0 2790.0 1935.0 1687.5 DrawSplineSection
	1935.0 1687.5 1935.0 585.0 1935.0 472.5 DrawSplineSection
	1935.0 472.5 1935.0 360.0 2047.5 360.0 DrawSplineSection
	2047.5 360.0 2160.0 360.0 2362.5 360.0 DrawSplineSection
	2565.0 360.0 l  gs col-1 s gr
 gr

% arrowhead
n 2418 330 m 2538 360 l 2418 390 l 2418 360 l 2418 330 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2418 2130 m 2538 2160 l 2418 2190 l 2580 2190 l 2580 2130 l  cp clip
n 1665.0 3285.0 m 1867.5 3285.0 l
	1867.5 3285.0 2070.0 3285.0 2070.0 3172.5 DrawSplineSection
	2070.0 3172.5 2070.0 3060.0 2070.0 2700.0 DrawSplineSection
	2070.0 2700.0 2070.0 2340.0 2070.0 2250.0 DrawSplineSection
	2070.0 2250.0 2070.0 2160.0 2160.0 2160.0 DrawSplineSection
	2160.0 2160.0 2250.0 2160.0 2407.5 2160.0 DrawSplineSection
	2565.0 2160.0 l  gs col-1 s gr
 gr

% arrowhead
n 2418 2130 m 2538 2160 l 2418 2190 l 2418 2160 l 2418 2130 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4857 4609 m 4745 4662 l 4819 4563 l 4694 4667 l 4733 4713 l  cp clip
n 5040.0 3150.0 m 5332.5 3150.0 l
	5332.5 3150.0 5625.0 3150.0 5737.5 3150.0 DrawSplineSection
	5737.5 3150.0 5850.0 3150.0 5850.0 3262.5 DrawSplineSection
	5850.0 3262.5 5850.0 3375.0 5850.0 3780.0 DrawSplineSection
	5850.0 3780.0 5850.0 4185.0 5850.0 4320.0 DrawSplineSection
	5850.0 4320.0 5850.0 4455.0 5715.0 4455.0 DrawSplineSection
	5715.0 4455.0 5580.0 4455.0 5287.5 4455.0 DrawSplineSection
	5287.5 4455.0 4995.0 4455.0 4860.0 4567.5 DrawSplineSection
	4725.0 4680.0 l  gs col-1 s gr
 gr

% arrowhead
n 4857 4609 m 4745 4662 l 4819 4563 l 4838 4586 l 4857 4609 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2832 4609 m 2720 4662 l 2794 4563 l 2669 4667 l 2708 4713 l  cp clip
n 3015.0 3150.0 m 3420.0 3150.0 l
	3420.0 3150.0 3825.0 3150.0 3937.5 3150.0 DrawSplineSection
	3937.5 3150.0 4050.0 3150.0 4050.0 3262.5 DrawSplineSection
	4050.0 3262.5 4050.0 3375.0 4050.0 3780.0 DrawSplineSection
	4050.0 3780.0 4050.0 4185.0 4050.0 4320.0 DrawSplineSection
	4050.0 4320.0 4050.0 4455.0 3915.0 4455.0 DrawSplineSection
	3915.0 4455.0 3780.0 4455.0 3375.0 4455.0 DrawSplineSection
	3375.0 4455.0 2970.0 4455.0 2835.0 4567.5 DrawSplineSection
	2700.0 4680.0 l  gs col-1 s gr
 gr

% arrowhead
n 2832 4609 m 2720 4662 l 2794 4563 l 2813 4586 l 2832 4609 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
540 900 m
gs 1 -1 sc (utility) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1455 m
gs 1 -1 sc (into) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2790 m
gs 1 -1 sc (unique) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3075 m
gs 1 -1 sc (rtable) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3600 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3315 m
gs 1 -1 sc (targetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3885 m
gs 1 -1 sc (groupClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 5220 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1170 m
gs 1 -1 sc (resultRelation:    0) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1980 m
gs 1 -1 sc (isBinary:         false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2265 m
gs 1 -1 sc (union_all:        false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4410 m
gs 1 -1 sc (hasAggs:         false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4695 m
gs 1 -1 sc (hasSublinks:    false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
945 360 m
gs 1 -1 sc (Query) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 630 m
gs 1 -1 sc (command:           1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3420 1125 m
gs 1 -1 sc ("supplier") col-1 sh gr
/Times-Roman ff 150.00 scf sf
3420 1395 m
gs 1 -1 sc ("s") col-1 sh gr
/Times-Roman ff 150.00 scf sf
5445 1125 m
gs 1 -1 sc ("sells") col-1 sh gr
/Times-Roman ff 150.00 scf sf
5445 1395 m
gs 1 -1 sc ("se") col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 1395 m
gs 1 -1 sc (refname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4590 900 m
gs 1 -1 sc (RTE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 1125 m
gs 1 -1 sc (relname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 1665 m
gs 1 -1 sc (relid: 18219) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3420 4275 m
gs 1 -1 sc ("sname") col-1 sh gr
/Times-Roman ff 150.00 scf sf
5445 4275 m
gs 1 -1 sc ("pno") col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 4275 m
gs 1 -1 sc (resname ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 4005 m
gs 1 -1 sc (resno:     1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 4275 m
gs 1 -1 sc (resname ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 4005 m
gs 1 -1 sc (resno:     2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4410 3780 m
gs 1 -1 sc (RESDOM) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2385 3780 m
gs 1 -1 sc (RESDOM) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 4860 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 5085 m
gs 1 -1 sc (varno:     1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 5085 m
gs 1 -1 sc (varno:     2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4545 4860 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1695 m
gs 1 -1 sc (isPortal:          false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2505 m
gs 1 -1 sc (sortClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4125 m
gs 1 -1 sc (havingQual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4935 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 5355 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 5355 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 427 2501 a(Figure)i(3.4:)j(T)n(ransformed)d
Fp(T)-5 b(ar)n(getList)12 b Ft(and)h Fp(F)m(r)n(omList)g
Ft(for)e(query)h(of)g(e)o(xample)h(3.1)270 2745 y(Figure)g(3.5)g(sho)o
(ws)h(the)g(transformed)e Fp(wher)n(e)i(clause)p Ft(.)20
b(Ev)o(ery)13 b Fr(A)p 1411 2745 15 2 v 18 w(Expr)g Ft(node)h(is)f
(transformed)g(to)g(an)270 2804 y Fr(Expr)k Ft(node.)31
b(The)18 b Fr(Attr)f Ft(nodes)g(representing)g(the)g(attrib)o(utes)g
(are)g(replaced)g(by)h Fr(VAR)f Ft(nodes)h(as)270 2864
y(it)d(has)g(been)g(done)g(for)f(the)h Fp(tar)n(getlist)g
Ft(abo)o(v)o(e.)24 b(Checks)15 b(if)g(the)f(appearing)h
Fp(attrib)o(utes)g Ft(are)g(v)o(alid)f(and)270 2924 y(kno)o(wn)h(to)g
(the)h(system)g(are)f(made.)26 b(If)14 b(there)i(is)f(an)h
Fp(attrib)o(ute)f Ft(used)h(which)f(is)h(not)g(kno)o(wn)f(an)g(error)
270 2984 y(will)d(be)g(returned)g(and)g(the)h Fp(query)f(pr)n(ocessing)
i Ft(will)d(be)i(aborted.)270 3103 y(The)30 b(whole)g
Fp(tr)o(ansformation)g(pr)n(ocess)g Ft(performs)f(a)h(transformation)e
(of)h(the)h(data)g(structure)270 3163 y(handed)13 b(back)f(by)h(the)g
Fp(parser)g Ft(to)g(a)f(more)h(comfortable)e(form.)16
b(The)d(character)f(strings)h(representing)270 3223 y(the)g
Fp(r)n(elations)h Ft(and)f Fp(attrib)o(utes)h Ft(in)f(the)g(original)g
(tree)g(are)g(replaced)g(by)g Fp(r)n(elation)h(ids)f
Ft(and)h Fr(VAR)f Ft(nodes)270 3283 y(whose)18 b(\002elds)g(are)g
(referring)e(to)i(the)f(entries)h(of)f(the)h Fp(r)o(ange)g(table)g
(entry)g(list)p Ft(.)32 b(In)17 b(addition)g(to)h(the)270
3342 y(transformation,)c(also)g(v)o(arious)g(checks)h(if)f(the)g(used)h
Fp(r)n(elation)f Ft(and)g Fp(attrib)o(ute)g Ft(names)h(\(appearing)e
(in)270 3402 y(the)f(query\))g(are)g(v)o(alid)g(in)g(the)g(current)g
(conte)o(xt)g(are)h(performed.)p eop
%%Page: 57 57
57 56 bop 198 60 a Fm(3.3.)29 b(THE)13 b(P)-5 b(ARSER)13
b(ST)-5 b(A)n(GE)1189 b Ft(57)291 2826 y @beginspecial
144 @llx 172 @lly 467 @urx 619 @ury 3230 @rwi @setspecial
%%BeginDocument: figures/transform_where.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
117.5 632.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1530 5040 m 1800 5310 l gs col-1 s gr 
% Polyline
n 1800 5040 m 1530 5310 l gs col-1 s gr 
% Polyline
n 1530 4770 m 1800 5040 l gs col-1 s gr 
% Polyline
n 1800 4770 m 1530 5040 l gs col-1 s gr 
% Polyline
n 1530 3960 m 1800 4230 l gs col-1 s gr 
% Polyline
n 1800 3960 m 1530 4230 l gs col-1 s gr 
% Polyline
n 1530 3690 m 1800 3960 l gs col-1 s gr 
% Polyline
n 1800 3690 m 1530 3960 l gs col-1 s gr 
% Polyline
n 1530 2340 m 1800 2610 l gs col-1 s gr 
% Polyline
n 1800 2340 m 1530 2610 l gs col-1 s gr 
% Polyline
n 1530 1260 m 1800 1530 l gs col-1 s gr 
% Polyline
n 1800 1260 m 1530 1530 l gs col-1 s gr 
% Polyline
n 1530 720 m 1800 990 l gs col-1 s gr 
% Polyline
n 1800 720 m 1530 990 l gs col-1 s gr 
% Polyline
n 5130 1440 m 5130 1710 l gs col-1 s gr 
% Polyline
n 4860 1440 m 5400 1440 l 5400 1710 l 4860 1710 l cp gs col-1 s gr 
% Polyline
n 5130 1440 m 5400 1710 l gs col-1 s gr 
% Polyline
n 5400 1440 m 5130 1710 l gs col-1 s gr 
% Polyline
n 4140 1440 m 4140 1710 l gs col-1 s gr 
% Polyline
n 3870 1440 m 4410 1440 l 4410 1710 l 3870 1710 l cp gs col-1 s gr 
% Polyline
gs  clippath
4713 1545 m 4833 1575 l 4713 1605 l 4875 1605 l 4875 1545 l  cp clip
n 4275 1575 m 4860 1575 l gs col-1 s gr gr

% arrowhead
n 4713 1545 m 4833 1575 l 4713 1605 l 4713 1575 l 4713 1545 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 4140 5940 m 4140 6210 l gs col-1 s gr 
% Polyline
n 3870 5940 m 4410 5940 l 4410 6210 l 3870 6210 l cp gs col-1 s gr 
% Polyline
n 4905 5940 m 4905 6210 l gs col-1 s gr 
% Polyline
n 4635 5940 m 5175 5940 l 5175 6210 l 4635 6210 l cp gs col-1 s gr 
% Polyline
n 4905 5940 m 5175 6210 l gs col-1 s gr 
% Polyline
n 5175 5940 m 4905 6210 l gs col-1 s gr 
% Polyline
n 3870 2295 m 4635 2295 l gs col-1 s gr 
% Polyline
n 3870 2565 m 4635 2565 l gs col-1 s gr 
% Polyline
n 3870 2070 m 4635 2070 l 4635 2835 l 3870 2835 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4095 2250 m
gs 1 -1 sc (Oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3960 2475 m
gs 1 -1 sc (opno: 521) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3960 2745 m
gs 1 -1 sc (opid:     0) col-1 sh gr
% Polyline
n 4140 3015 m 4140 3285 l gs col-1 s gr 
% Polyline
n 3870 3015 m 4410 3015 l 4410 3285 l 3870 3285 l cp gs col-1 s gr 
% Polyline
n 4905 3015 m 4905 3285 l gs col-1 s gr 
% Polyline
n 4635 3015 m 5175 3015 l 5175 3285 l 4635 3285 l cp gs col-1 s gr 
% Polyline
n 4905 3015 m 5175 3285 l gs col-1 s gr 
% Polyline
n 5175 3015 m 4905 3285 l gs col-1 s gr 
% Polyline
n 450 450 m 1800 450 l gs col-1 s gr 
% Polyline
n 450 720 m 1800 720 l gs col-1 s gr 
% Polyline
n 450 990 m 1800 990 l gs col-1 s gr 
% Polyline
n 450 1260 m 1800 1260 l gs col-1 s gr 
% Polyline
n 450 1530 m 1800 1530 l gs col-1 s gr 
% Polyline
n 450 1800 m 1800 1800 l gs col-1 s gr 
% Polyline
n 450 2070 m 1800 2070 l gs col-1 s gr 
% Polyline
n 450 2340 m 1800 2340 l gs col-1 s gr 
% Polyline
n 450 2610 m 1800 2610 l gs col-1 s gr 
% Polyline
n 450 2880 m 1800 2880 l gs col-1 s gr 
% Polyline
n 450 3150 m 1800 3150 l gs col-1 s gr 
% Polyline
n 450 3690 m 1800 3690 l gs col-1 s gr 
% Polyline
n 450 3960 m 1800 3960 l gs col-1 s gr 
% Polyline
n 450 4230 m 1800 4230 l gs col-1 s gr 
% Polyline
n 450 3420 m 1800 3420 l gs col-1 s gr 
% Polyline
n 450 4500 m 1800 4500 l gs col-1 s gr 
% Polyline
n 450 4770 m 1800 4770 l gs col-1 s gr 
% Polyline
n 450 5040 m 1800 5040 l gs col-1 s gr 
% Polyline
n 450 225 m 1800 225 l 1800 5310 l 450 5310 l cp gs col-1 s gr 
% Polyline
n 1530 4770 m 1530 5310 l gs col-1 s gr 
% Polyline
n 1530 4230 m 1530 2880 l gs col-1 s gr 
% Polyline
n 1530 2340 m 1530 2610 l gs col-1 s gr 
% Polyline
n 1530 720 m 1530 990 l gs col-1 s gr 
% Polyline
n 1530 1260 m 1530 1530 l gs col-1 s gr 
% Polyline
n 1530 2610 m 1530 2880 l gs col-1 s gr 
% Polyline
n 1530 2610 m 1800 2880 l gs col-1 s gr 
% Polyline
n 1800 2610 m 1530 2880 l gs col-1 s gr 
% Polyline
n 3150 1170 m 3420 1440 l gs col-1 s gr 
% Polyline
n 3420 1170 m 3150 1440 l gs col-1 s gr 
% Polyline
gs  clippath
3723 1545 m 3843 1575 l 3723 1605 l 3885 1605 l 3885 1545 l  cp clip
n 3285 1575 m 3870 1575 l gs col-1 s gr gr

% arrowhead
n 3723 1545 m 3843 1575 l 3723 1605 l 3723 1575 l 3723 1545 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2430 5220 m 3420 5220 l gs col-1 s gr 
% Polyline
n 2430 5490 m 3420 5490 l gs col-1 s gr 
% Polyline
n 2430 5760 m 3420 5760 l gs col-1 s gr 
% Polyline
n 2430 4995 m 3420 4995 l 3420 6030 l 2430 6030 l cp gs col-1 s gr 
% Polyline
n 3150 6030 m 3150 5490 l gs col-1 s gr 
% Polyline
gs  clippath
4488 6045 m 4608 6075 l 4488 6105 l 4650 6105 l 4650 6045 l  cp clip
n 4275 6075 m 4635 6075 l gs col-1 s gr gr

% arrowhead
n 4488 6045 m 4608 6075 l 4488 6105 l 4488 6075 l 4488 6045 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3870 5220 m 4635 5220 l gs col-1 s gr 
% Polyline
n 3870 5490 m 4635 5490 l gs col-1 s gr 
% Polyline
n 3870 4995 m 4635 4995 l 4635 5760 l 3870 5760 l cp gs col-1 s gr 
% Polyline
n 2970 6750 m 3870 6750 l gs col-1 s gr 
% Polyline
n 2970 7020 m 3870 7020 l gs col-1 s gr 
% Polyline
n 4275 6750 m 5175 6750 l gs col-1 s gr 
% Polyline
n 4275 7020 m 5175 7020 l gs col-1 s gr 
% Polyline
n 2970 6525 m 3870 6525 l 3870 7290 l 2970 7290 l cp gs col-1 s gr 
% Polyline
n 4275 6525 m 5175 6525 l 5175 7290 l 4275 7290 l cp gs col-1 s gr 
% Polyline
n 2430 2295 m 3420 2295 l gs col-1 s gr 
% Polyline
n 2430 2565 m 3420 2565 l gs col-1 s gr 
% Polyline
n 2430 2835 m 3420 2835 l gs col-1 s gr 
% Polyline
n 2430 2070 m 3420 2070 l 3420 3105 l 2430 3105 l cp gs col-1 s gr 
% Polyline
n 3150 3105 m 3150 2565 l gs col-1 s gr 
% Polyline
gs  clippath
4488 3120 m 4608 3150 l 4488 3180 l 4650 3180 l 4650 3120 l  cp clip
n 4275 3150 m 4635 3150 l gs col-1 s gr gr

% arrowhead
n 4488 3120 m 4608 3150 l 4488 3180 l 4488 3150 l 4488 3120 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 4275 3825 m 5175 3825 l gs col-1 s gr 
% Polyline
n 4275 3600 m 5175 3600 l 5175 4095 l 4275 4095 l cp gs col-1 s gr 
% Polyline
n 2970 3824 m 3870 3824 l gs col-1 s gr 
% Polyline
n 2970 4094 m 3870 4094 l gs col-1 s gr 
% Polyline
n 2970 3600 m 3870 3600 l 3870 4365 l 2970 4365 l cp gs col-1 s gr 
% Polyline
n 2430 900 m 3420 900 l gs col-1 s gr 
% Polyline
n 2430 1170 m 3420 1170 l gs col-1 s gr 
% Polyline
n 2430 1440 m 3420 1440 l gs col-1 s gr 
% Polyline
n 2430 675 m 3420 675 l 3420 1710 l 2430 1710 l cp gs col-1 s gr 
% Polyline
n 3150 1710 m 3150 1170 l gs col-1 s gr 
% Open spline
gs  clippath
2955 528 m 2925 648 l 2895 528 l 2895 690 l 2955 690 l  cp clip
n 1665.0 3555.0 m 1890.0 3555.0 l
	1890.0 3555.0 2115.0 3555.0 2115.0 3397.5 DrawSplineSection
	2115.0 3397.5 2115.0 3240.0 2115.0 2047.5 DrawSplineSection
	2115.0 2047.5 2115.0 855.0 2115.0 585.0 DrawSplineSection
	2115.0 585.0 2115.0 315.0 2340.0 315.0 DrawSplineSection
	2340.0 315.0 2565.0 315.0 2677.5 315.0 DrawSplineSection
	2677.5 315.0 2790.0 315.0 2857.5 360.0 DrawSplineSection
	2857.5 360.0 2925.0 405.0 2925.0 540.0 DrawSplineSection
	2925.0 675.0 l  gs col-1 s gr
 gr

% arrowhead
n 2955 528 m 2925 648 l 2895 528 l 2925 528 l 2955 528 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3050 1987 m 2944 2050 l 3008 1945 l 2893 2059 l 2936 2102 l  cp clip
n 4005.0 1575.0 m 4005.0 1687.5 l
	4005.0 1687.5 4005.0 1800.0 3937.5 1845.0 DrawSplineSection
	3937.5 1845.0 3870.0 1890.0 3487.5 1890.0 DrawSplineSection
	3487.5 1890.0 3105.0 1890.0 3015.0 1980.0 DrawSplineSection
	2925.0 2070.0 l  gs col-1 s gr
 gr

% arrowhead
n 3050 1987 m 2944 2050 l 3008 1945 l 3029 1966 l 3050 1987 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3723 5325 m 3843 5355 l 3723 5385 l 3885 5385 l 3885 5325 l  cp clip
n 3285.0 5625.0 m 3420.0 5625.0 l
	3420.0 5625.0 3555.0 5625.0 3555.0 5490.0 DrawSplineSection
	3555.0 5490.0 3555.0 5355.0 3712.5 5355.0 DrawSplineSection
	3870.0 5355.0 l  gs col-1 s gr
 gr

% arrowhead
n 3723 5325 m 3843 5355 l 3723 5385 l 3723 5355 l 3723 5325 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3723 6045 m 3843 6075 l 3723 6105 l 3885 6105 l 3885 6045 l  cp clip
n 3285.0 5895.0 m 3397.5 5895.0 l
	3397.5 5895.0 3510.0 5895.0 3532.5 5985.0 DrawSplineSection
	3532.5 5985.0 3555.0 6075.0 3712.5 6075.0 DrawSplineSection
	3870.0 6075.0 l  gs col-1 s gr
 gr

% arrowhead
n 3723 6045 m 3843 6075 l 3723 6105 l 3723 6075 l 3723 6045 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4783 6387 m 4730 6498 l 4724 6375 l 4693 6534 l 4751 6546 l  cp clip
n 4770.0 6075.0 m 4770.0 6187.5 l
	4770.0 6187.5 4770.0 6300.0 4747.5 6412.5 DrawSplineSection
	4725.0 6525.0 l  gs col-1 s gr
 gr

% arrowhead
n 4783 6387 m 4730 6498 l 4724 6375 l 4754 6381 l 4783 6387 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3554 6457 m 3441 6508 l 3516 6410 l 3390 6511 l 3427 6558 l  cp clip
n 4005.0 6075.0 m 4005.0 6187.5 l
	4005.0 6187.5 4005.0 6300.0 3825.0 6322.5 DrawSplineSection
	3825.0 6322.5 3645.0 6345.0 3532.5 6435.0 DrawSplineSection
	3420.0 6525.0 l  gs col-1 s gr
 gr

% arrowhead
n 3554 6457 m 3441 6508 l 3516 6410 l 3535 6433 l 3554 6457 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2955 4848 m 2925 4968 l 2895 4848 l 2895 5010 l 2955 5010 l  cp clip
n 4995.0 1575.0 m 4995.0 1755.0 l
	4995.0 1755.0 4995.0 1935.0 5062.5 1980.0 DrawSplineSection
	5062.5 1980.0 5130.0 2025.0 5332.5 2025.0 DrawSplineSection
	5332.5 2025.0 5535.0 2025.0 5535.0 2205.0 DrawSplineSection
	5535.0 2205.0 5535.0 2385.0 5535.0 3375.0 DrawSplineSection
	5535.0 3375.0 5535.0 4365.0 5535.0 4545.0 DrawSplineSection
	5535.0 4545.0 5535.0 4725.0 5310.0 4725.0 DrawSplineSection
	5310.0 4725.0 5085.0 4725.0 4162.5 4725.0 DrawSplineSection
	4162.5 4725.0 3240.0 4725.0 3082.5 4725.0 DrawSplineSection
	3082.5 4725.0 2925.0 4725.0 2925.0 4860.0 DrawSplineSection
	2925.0 4995.0 l  gs col-1 s gr
 gr

% arrowhead
n 2955 4848 m 2925 4968 l 2895 4848 l 2925 4848 l 2955 4848 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3723 2400 m 3843 2430 l 3723 2460 l 3885 2460 l 3885 2400 l  cp clip
n 3285.0 2700.0 m 3420.0 2700.0 l
	3420.0 2700.0 3555.0 2700.0 3555.0 2565.0 DrawSplineSection
	3555.0 2565.0 3555.0 2430.0 3712.5 2430.0 DrawSplineSection
	3870.0 2430.0 l  gs col-1 s gr
 gr

% arrowhead
n 3723 2400 m 3843 2430 l 3723 2460 l 3723 2430 l 3723 2400 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3723 3120 m 3843 3150 l 3723 3180 l 3885 3180 l 3885 3120 l  cp clip
n 3285.0 2970.0 m 3397.5 2970.0 l
	3397.5 2970.0 3510.0 2970.0 3532.5 3060.0 DrawSplineSection
	3532.5 3060.0 3555.0 3150.0 3712.5 3150.0 DrawSplineSection
	3870.0 3150.0 l  gs col-1 s gr
 gr

% arrowhead
n 3723 3120 m 3843 3150 l 3723 3180 l 3723 3150 l 3723 3120 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4783 3462 m 4730 3573 l 4724 3450 l 4693 3609 l 4751 3621 l  cp clip
n 4770.0 3150.0 m 4770.0 3262.5 l
	4770.0 3262.5 4770.0 3375.0 4747.5 3487.5 DrawSplineSection
	4725.0 3600.0 l  gs col-1 s gr
 gr

% arrowhead
n 4783 3462 m 4730 3573 l 4724 3450 l 4754 3456 l 4783 3462 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3554 3532 m 3441 3583 l 3516 3485 l 3390 3586 l 3427 3633 l  cp clip
n 4005.0 3150.0 m 4005.0 3262.5 l
	4005.0 3262.5 4005.0 3375.0 3825.0 3397.5 DrawSplineSection
	3825.0 3397.5 3645.0 3420.0 3532.5 3510.0 DrawSplineSection
	3420.0 3600.0 l  gs col-1 s gr
 gr

% arrowhead
n 3554 3532 m 3441 3583 l 3516 3485 l 3535 3508 l 3554 3532 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
540 900 m
gs 1 -1 sc (utility) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2505 m
gs 1 -1 sc (sortClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2790 m
gs 1 -1 sc (unique) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3075 m
gs 1 -1 sc (rtable) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3600 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3315 m
gs 1 -1 sc (targetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 3885 m
gs 1 -1 sc (groupClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 5220 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1170 m
gs 1 -1 sc (resultRelation:    0) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1980 m
gs 1 -1 sc (isBinary:         false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2265 m
gs 1 -1 sc (union_all:        false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4410 m
gs 1 -1 sc (hasAggs:         false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4695 m
gs 1 -1 sc (hasSublinks:    false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
945 360 m
gs 1 -1 sc (Query) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 630 m
gs 1 -1 sc (command:           1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 5400 m
gs 1 -1 sc (opType:  OP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 5925 m
gs 1 -1 sc (args) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2790 5175 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4095 5175 m
gs 1 -1 sc (Oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3960 5400 m
gs 1 -1 sc (opno:  96) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3960 5670 m
gs 1 -1 sc (opid:     0) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 6705 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 6930 m
gs 1 -1 sc (varno:     1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 6930 m
gs 1 -1 sc (varno:     2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4545 6705 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 7200 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 7200 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 2475 m
gs 1 -1 sc (opType:  OP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 3000 m
gs 1 -1 sc (args) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2790 2250 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4545 3780 m
gs 1 -1 sc (Const) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 3780 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 4004 m
gs 1 -1 sc (varno:     1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 4275 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4320 4005 m
gs 1 -1 sc (constvalue: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4935 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4125 m
gs 1 -1 sc (havingQual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1455 m
gs 1 -1 sc (into) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1695 m
gs 1 -1 sc (isPortal:          false) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 5685 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 2760 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 1080 m
gs 1 -1 sc (opType: AND) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 1605 m
gs 1 -1 sc (args) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2790 855 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 1365 m
gs 1 -1 sc (oper) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 464 2935 a(Figure)12 b(3.5:)j(T)n(ransformed)d
Fp(wher)n(e)i(clause)f Ft(for)e(query)h(of)g(e)o(xample)g(3.1)p
eop
%%Page: 58 58
58 57 bop 270 60 a Ft(58)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Fi(3.4)71 b(The)18 b(P)o(ostgr)o(eSQL)e(Rule)h(System)270
349 y Ft(PostgreSQL)c(supports)g(a)h(po)o(werful)e Fp(rule)h(system)i
Ft(for)d(the)h(speci\002cation)h(of)f Fp(vie)o(ws)h Ft(and)f(ambiguous)
270 409 y Fp(vie)o(w)g(updates)p Ft(.)j(Originally)11
b(the)h(PostgreSQL)g Fp(rule)h(system)g Ft(consisted)g(of)f(two)g
(implementations.)345 471 y(The)18 b(\002rst)g(one)f(worked)g(using)h
Fp(tuple)f(le)o(vel)i Ft(processing)f(and)f(was)h(implemented)f(deep)h
(in)g(the)270 531 y Fp(e)o(xecutor)p Ft(.)35 b(The)19
b Fp(rule)g(system)g Ft(was)g(called)f(whene)o(v)o(er)h(an)f(indi)o
(vidual)g(tuple)g(had)h(been)f(accessed.)270 591 y(This)11
b(implementation)d(has)j(been)f(remo)o(v)o(ed)f(in)h(1995)g(when)g(the)
g(last)g(of)o(\002cial)f(release)h(of)f(the)h(Postgres)270
650 y(project)i(was)g(further)f(enhanced)i(to)f(Postgres95.)345
712 y(The)22 b(second)h(implementation)d(of)i(the)g Fp(rule)g(system)h
Ft(is)f(a)g(technique)g(called)g Fp(query)g(r)n(e)o(writ-)270
772 y(ing)p Ft(.)32 b(The)18 b Fp(r)n(e)o(write)h(system)g
Ft(is)f(a)g(module)f(that)h(e)o(xists)g(between)g(the)g
Fp(parser)g(stage)f Ft(and)h(the)g Fp(plan-)270 832 y(ner/optimizer)p
Ft(.)e(This)d(technique)f(is)h(still)f(implemented.)345
894 y(F)o(or)h(information)f(on)i(the)f(syntax)h(and)g(creation)f(of)g
Fp(rules)i Ft(in)e(the)h(PostgreSQL)f(system)h(refer)f(to)270
953 y(section)g(2.5.8)g Fp(Rules)g(in)f(P)l(ostgr)n(eSQL)p
Ft(.)270 1107 y Fh(3.4.1)59 b(The)15 b(Rewrite)e(System)270
1205 y Ft(The)g Fp(query)g(r)n(e)o(write)h Ft(system)e(is)h(a)g(module)
e(between)i(the)f Fp(parser)h(stage)f Ft(and)g(the)h
Fp(planner/optimizer)p Ft(.)270 1264 y(It)e(processes)h(the)g(tree)f
(handed)g(back)g(by)h(the)f Fp(parser)h(stage)f Ft(\(which)f
(represents)i(a)f(user)h(query\))e(and)i(if)270 1324
y(there)h(is)g(a)h Fp(rule)f Ft(present)h(that)f(has)g(to)g(be)h
(applied)f(to)g(the)g(query)g(it)g Fp(r)n(e)o(writes)i
Ft(the)e(tree)g(to)g(an)g(alternate)270 1384 y(form.)270
1528 y Fn(T)-5 b(echniques)12 b(T)-5 b(o)13 b(Implement)g(V)n(iews)270
1625 y Ft(No)o(w)f(will)h(sketch)f(the)h(algorithm)f(of)g(the)h
Fp(query)g(r)n(e)o(write)h(system)p Ft(.)k(F)o(or)12
b(better)g(illustration)g(we)h(sho)o(w)270 1685 y(ho)o(w)f(to)g
(implement)g Fp(vie)o(ws)h Ft(using)g(rules)f(as)h(an)f(e)o(xample.)270
1805 y(Let)h(the)f(follo)o(wing)f Fp(rule)i Ft(be)f(gi)o(v)o(en:)330
1913 y Fr(create)29 b(rule)g(view_rule)330 1972 y(as)g(on)h(select)330
2032 y(to)f(test_view)330 2092 y(do)g(instead)419 2152
y(select)h(s.sname,)f(p.pname)419 2211 y(from)h(supplier)f(s,)h(sells)f
(se,)g(part)h(p)419 2271 y(where)g(s.sno)f(=)h(se.sno)f(and)599
2331 y(p.pno)g(=)h(se.pno;)270 2437 y Ft(The)22 b(gi)o(v)o(en)f
Fp(rule)h Ft(will)f(be)g Fp(\002r)n(ed)h Ft(whene)o(v)o(er)f(a)h
Fr(select)e Ft(against)i(the)f Fp(r)n(elation)g Fr(test)p
1881 2437 15 2 v 18 w(view)g Ft(is)270 2497 y(detected.)16
b(Instead)c(of)f(selecting)h(the)g(tuples)g(from)f Fr(test)p
1298 2497 V 17 w(view)h Ft(the)f Fr(select)h Ft(statement)g(gi)o(v)o
(en)f(in)270 2556 y(the)h Fp(action)g(part)h Ft(of)f(the)g
Fp(rule)h Ft(is)f(e)o(x)o(ecuted.)270 2676 y(Let)h(the)f(follo)o(wing)f
(user)o(-query)h(against)g Fr(test)p 1128 2676 V 17 w(view)g
Ft(be)h(gi)o(v)o(en:)330 2784 y Fr(select)29 b(sname)330
2844 y(from)g(test_view)330 2903 y(where)g(sname)g(<>)h('Smith';)270
3009 y Ft(Here)17 b(is)g(a)g(list)g(of)f(the)h(steps)g(performed)f(by)g
(the)h Fp(query)h(r)n(e)o(write)g(system)f Ft(whene)o(v)o(er)g(a)g
(user)o(-query)270 3069 y(against)k Fr(test)p 555 3069
V 17 w(view)g Ft(appears.)41 b(\(The)21 b(follo)o(wing)e(listing)h(is)h
(a)g(v)o(ery)g(informal)e(description)i(of)270 3129 y(the)e(algorithm)f
(just)h(intended)f(for)g(basic)i(understanding.)35 b(F)o(or)18
b(a)h(detailed)g(description)f(refer)g(to)270 3189 y([ST)o(ON89]\).)345
3294 y Fo(\017)25 b Ft(T)l(ake)12 b(the)g(query)g(gi)o(v)o(en)g(in)h
(the)f Fp(action)g(part)g Ft(of)g(the)h Fp(rule)p Ft(.)345
3402 y Fo(\017)25 b Ft(Adapt)9 b(the)g Fp(tar)n(getlist)g
Ft(to)h(meet)f(the)h(number)e(and)i(order)f(of)g(attrib)o(utes)g(gi)o
(v)o(en)g(in)g(the)h(user)o(-query)m(.)p eop
%%Page: 59 59
59 58 bop 198 60 a Fm(3.5.)29 b(PLANNER/OPTIMIZER)1139
b Ft(59)273 234 y Fo(\017)25 b Ft(Add)12 b(the)g(quali\002cation)f(gi)o
(v)o(en)i(in)f(the)g Fp(wher)n(e)h(clause)g Ft(of)f(the)g(user)o
(-query)g(to)g(the)g(quali\002cation)323 294 y(of)f(the)i(query)f(gi)o
(v)o(en)g(in)g(the)g Fp(action)g(part)h Ft(of)f(the)g
Fp(rule)p Ft(.)198 394 y(Gi)o(v)o(en)e(the)g Fp(rule)g(de\002nition)g
Ft(abo)o(v)o(e,)h(the)f(user)o(-query)f(will)h(be)g(re)o(written)f(to)h
(the)g(follo)o(wing)f(form)g(\(Note)198 454 y(that)14
b(the)h Fp(r)n(e)o(writing)g Ft(is)g(done)f(on)h(the)f(internal)g
(representation)g(of)g(the)g(user)o(-query)g(handed)h(back)f(by)198
513 y(the)e Fp(parser)h(stage)f Ft(b)o(ut)g(the)g(deri)o(v)o(ed)g(ne)o
(w)g(data)h(structure)f(will)g(represent)g(the)g(follo)o(wing)f
(query\):)258 614 y Fr(select)29 b(s.sname)258 673 y(from)g(supplier)g
(s,)h(sells)f(se,)h(part)f(p)258 733 y(where)g(s.sno)g(=)h(se.sno)f
(and)437 793 y(p.pno)g(=)h(se.pno)f(and)437 853 y(s.sname)g(<>)h
('Smith;)198 1022 y Fi(3.5)71 b(Planner/Optimizer)198
1133 y Ft(The)10 b(task)h(of)e(the)h Fp(planner/optimizer)g
Ft(is)g(to)f(create)h(an)g(optimal)f Fp(e)o(xecution)h(plan)p
Ft(.)15 b(It)9 b(\002rst)g(combines)h(all)198 1193 y(possible)k(ways)f
(of)g Fp(scanning)g Ft(and)g Fp(joining)g Ft(the)g Fp(r)n(elations)h
Ft(that)f(appear)g(in)g(a)g(query)m(.)18 b(All)13 b(the)g(created)198
1253 y(paths)h(lead)g(to)g(the)g(same)g(result)g(and)g(it')m(s)f(the)h
Fp(optimizer')n(s)g Ft(task)h(to)e(estimate)h(the)g(cost)g(of)g(e)o(x)o
(ecuting)198 1313 y(each)f(path)f(and)g(\002nd)g(out)g(which)h(one)f
(is)h(the)f(cheapest.)198 1456 y Fh(3.5.1)59 b(Generating)13
b(P)o(ossible)h(Plans)198 1550 y Ft(The)j Fp(planner/optimizer)f
Ft(decides)h(which)f(plans)g(should)g(be)g(generated)g(based)h(upon)f
(the)g(types)h(of)198 1609 y(indices)g(de\002ned)g(on)g(the)g
(relations)g(appearing)g(in)g(a)g(query)m(.)29 b(There)18
b(is)f(always)g(the)g(possibility)g(of)198 1669 y(performing)10
b(a)j Fp(sequential)f(scan)g Ft(on)g(a)h(relation,)f(so)g(a)g
Fp(plan)g Ft(using)g(only)g Fp(sequential)g(scans)h Ft(is)g(always)198
1729 y(created.)j(Assume)c(an)h(inde)o(x)f(is)g(de\002ned)g(on)g(a)h
(relation)e(\(for)g(e)o(xample)h(a)h(B-tree)e(inde)o(x\))h(and)g(a)h
(query)198 1789 y(contains)20 b(the)f(restriction)g Fp(r)n
(elation.attrib)o(ute)12 b(OPR)i(constant)o Ft(.)38 b(If)19
b Fp(r)n(elation.attrib)o(ute)g Ft(happens)h(to)198 1848
y(match)e(the)g(ke)o(y)f(of)h(the)g(B-tree)f(inde)o(x)h(and)g
Fp(OPR)h Ft(is)f(an)o(ything)f(b)o(ut)h(')p Fo(6)p Fl(=)p
Ft(')f(another)g(plan)h(is)g(created)198 1908 y(using)h(the)f(B-tree)h
(inde)o(x)f(to)h(scan)g(the)g(relation.)34 b(If)18 b(there)g(are)h
(further)e(indices)i(present)f(and)h(the)198 1968 y(restrictions)10
b(in)h(the)g(query)g(happen)f(to)h(match)g(a)g(ke)o(y)g(of)f(an)h(inde)
o(x)g(further)f(plans)h(will)g(be)g(considered.)273 2028
y(After)g(all)h(feasible)h(plans)f(ha)o(v)o(e)h(been)g(found)e(for)h
(scanning)g(single)h Fp(r)n(elations)p Ft(,)g(plans)f(for)g(joining)198
2088 y Fp(r)n(elations)i Ft(are)f(created.)20 b(The)14
b Fp(planner/optimizer)g Ft(considers)f(only)h(joins)f(between)h(e)o(v)
o(ery)f(two)g Fp(r)n(ela-)198 2147 y(tions)j Ft(for)g(which)g(there)h
(e)o(xists)g(a)g(corresponding)e Fp(join)h(clause)h Ft(\(i.e.)28
b(for)16 b(which)g(a)h(restriction)f(like)198 2207 y
Fk(:)8 b(:)g(:)18 b Fp(wher)n(e)g(r)n(el1.attr1=r)n(el2.attr2)h
Ft(e)o(xists\))f(in)f(the)h Fp(wher)n(e)g(quali\002cation)p
Ft(.)30 b(All)18 b(possible)f(plans)h(are)198 2267 y(generated)13
b(for)g(e)o(v)o(ery)h(join)f(pair)g(considered)h(by)f(the)h
Fp(planner/optimizer)p Ft(.)20 b(The)14 b(three)f(possible)h(join)198
2327 y(strate)o(gies)f(are:)273 2427 y Fo(\017)25 b Fp(nested)13
b(iter)o(ation)g(join)p Ft(:)j(The)e(right)e Fp(r)n(elation)h
Ft(is)h(scanned)g(once)f(for)f(e)o(v)o(ery)h(tuple)g(found)f(in)h(the)
323 2487 y(left)e Fp(r)n(elation)p Ft(.)16 b(This)d(strate)o(gy)g(is)f
(easy)h(to)f(implement)g(b)o(ut)g(can)h(be)f(v)o(ery)g(time)g
(consuming.)273 2587 y Fo(\017)25 b Fp(mer)n(ge)15 b(sort)g(join)p
Ft(:)20 b(Each)c(relation)e(is)h(sorted)g(on)g(the)g
Fp(join)g(attrib)o(utes)g Ft(before)f(the)h(join)f(starts.)323
2647 y(Then)i(the)h(two)e(relations)i(are)f Fp(mer)n(ged)g(together)g
Ft(taking)g(into)g(account)g(that)h(both)f Fp(r)n(elations)323
2706 y Ft(are)d(ordered)f(on)h(the)g Fp(join)g(attrib)o(utes)p
Ft(.)18 b(This)c(kind)f(of)g(join)g(is)g(more)g(attracti)o(v)o(e)f
(because)i(e)o(v)o(ery)323 2766 y Fp(r)n(elation)e Ft(has)h(to)f(be)g
(scanned)h(only)f(once.)273 2866 y Fo(\017)25 b Fp(hash)11
b(join)p Ft(:)j(the)d(right)f Fp(r)n(elation)h Ft(is)g(\002rst)g
(hashed)g(on)g(its)g Fp(join)g(attrib)o(utes)p Ft(.)k(Ne)o(xt)d(the)f
(left)f Fp(r)n(elation)323 2926 y Ft(is)k(scanned)i(and)e(the)h
(appropriate)e(v)o(alues)i(of)f(e)o(v)o(ery)g(tuple)h(found)e(are)i
(used)g(as)g Fp(hash)g(ke)o(ys)f Ft(to)323 2986 y(locate)e(the)g
(tuples)h(in)f(the)g(right)g Fp(r)n(elation)p Ft(.)198
3129 y Fh(3.5.2)59 b(Data)15 b(Structur)o(e)f(of)g(the)h(Plan)198
3223 y Ft(Here)e(we)g(will)g(gi)o(v)o(e)g(a)h(little)f(description)f
(of)h(the)g(nodes)h(appearing)e(in)i(the)f Fp(plan)p
Ft(.)18 b(Figure)12 b(3.6)i(sho)o(ws)198 3283 y(the)e
Fp(plan)g Ft(produced)g(for)g(the)g(query)g(in)g(e)o(xample)h(3.1.)273
3342 y(The)d(top)g(node)g(of)g(the)g Fp(plan)f Ft(is)i(a)f
Fr(MergeJoin)f Ft(node)h(which)g(has)g(two)g(successors,)i(one)e
(attached)198 3402 y(to)18 b(the)f(\002eld)h Fr(lefttree)f
Ft(and)h(the)f(second)i(attached)e(to)h(the)g(\002eld)f
Fr(righttree)p Ft(.)31 b(Each)19 b(of)e(the)p eop
%%Page: 60 60
60 59 bop 270 60 a Ft(60)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(subnodes)f(represents)f(one)g Fp(r)n(elation)h
Ft(of)f(the)g(join.)15 b(As)10 b(mentioned)g(abo)o(v)o(e)h(a)f
Fp(mer)n(ge)h(sort)g(join)f Ft(requires)270 294 y(each)h
Fp(r)n(elation)f Ft(to)g(be)g(sorted.)15 b(That')m(s)c(why)f(we)h
(\002nd)e(a)i Fr(Sort)f Ft(node)g(in)g(each)h(subplan.)k(The)c
(additional)270 354 y(quali\002cation)19 b(gi)o(v)o(en)g(in)g(the)h
(query)f(\()p Fk(s:sno)27 b(>)f Fl(2)p Ft(\))20 b(is)f(pushed)h(do)o
(wn)f(as)h(far)e(as)i(possible)g(and)g(is)270 413 y(attached)12
b(to)h(the)f Fr(qpqual)g Ft(\002eld)g(of)g(the)g(leaf)g
Fr(SeqScan)g Ft(node)g(of)g(the)g(corresponding)g(subplan.)345
494 y(The)k(list)f(attached)g(to)g(the)h(\002eld)f Fr(mergeclauses)f
Ft(of)g(the)i Fr(MergeJoin)e Ft(node)h(contains)h(in-)270
554 y(formation)e(about)h(the)g Fr(join)30 b(attributes)p
Ft(.)23 b(The)16 b(v)o(alues)g Fl(65000)f Ft(and)g Fl(65001)g
Ft(for)f(the)i Fr(varno)270 613 y Ft(\002elds)f(in)f(the)h
Fr(VAR)g Ft(nodes)g(appearing)f(in)h(the)g Fr(mergeclauses)e
Ft(list)i(\(and)f(also)h(in)g(the)g Fp(tar)n(getlist)p
Ft(\))270 673 y(mean)d(that)g(not)g(the)g(tuples)g(of)g(the)g(current)f
(node)i(should)f(be)g(considered)g(b)o(ut)g(the)g(tuples)g(of)g(the)g
(ne)o(xt)270 733 y(\224deeper\224)g(nodes)h(\(i.e.)j(the)c(top)g(nodes)
h(of)f(the)g(subplans\))h(should)f(be)h(used)f(instead.)345
813 y(Note)i(that)g(e)o(v)o(ery)h Fr(Sort)f Ft(and)g
Fr(SeqScan)g Ft(node)h(appearing)f(in)g(\002gure)g(3.6)g(has)h(got)g(a)
f Fp(tar)n(getlist)270 873 y Ft(b)o(ut)g(because)h(there)g(was)f(not)g
(enough)h(space)g(only)f(the)g(one)h(for)e(the)i Fr(MergeJoin)e
Ft(node)i(could)f(be)270 933 y(dra)o(wn.)345 1013 y(Another)c(task)i
(performed)d(by)i(the)g Fp(planner/optimizer)g Ft(is)h(\002xing)e(the)h
Fp(oper)o(ator)h(ids)f Ft(in)g(the)g Fr(Expr)270 1073
y Ft(and)16 b Fr(Oper)h Ft(nodes.)28 b(As)17 b(mentioned)e(earlier)n(,)
j(PostgreSQL)e(supports)g(a)h(v)o(ariety)e(of)h(dif)o(ferent)f(data)270
1133 y(types)f(and)f(e)o(v)o(en)g(user)h(de\002ned)f(types)g(can)h(be)f
(used.)20 b(T)l(o)13 b(be)h(able)f(to)g(maintain)g(the)g(huge)h(amount)
f(of)270 1193 y(functions)h(and)g(operators)g(it)g(is)h(necessary)g(to)
f(store)h(them)f(in)g(a)h Fp(system)g(table)p Ft(.)22
b(Each)15 b(function)e(and)270 1253 y(operator)e(gets)i(a)g(unique)f
Fp(oper)o(ator)h(id)p Ft(.)j(According)11 b(to)h(the)h(types)f(of)g
(the)h(attrib)o(utes)f(used)g(within)g(the)270 1312 y(quali\002cations)
g(etc.,)h(the)g(appropriate)e Fp(oper)o(ator)i(ids)g
Ft(ha)o(v)o(e)f(to)h(be)f(used.)270 1594 y Fi(3.6)71
b(Executor)270 1745 y Ft(The)12 b Fp(e)o(xecutor)f Ft(takes)g(the)g
Fp(plan)g Ft(handed)g(back)g(by)g(the)g Fp(planner/optimizer)g
Ft(and)g(starts)g(processing)g(the)270 1804 y(top)16
b(node.)27 b(In)15 b(the)h(case)h(of)f(our)f(e)o(xample)i(\(the)e
(query)h(gi)o(v)o(en)g(in)g(e)o(xample)g(3.1\))g(the)g(top)g(node)g(is)
g(a)270 1864 y Fr(MergeJoin)11 b Ft(node.)345 1945 y(Before)i(an)o(y)h
(mer)o(ge)f(can)g(be)h(done)f(two)g(tuples)h(ha)o(v)o(e)g(to)f(be)h
(fetched)f(\(one)g(from)f(each)i(subplan\).)270 2004
y(So)i(the)g Fp(e)o(xecutor)h Ft(recursi)o(v)o(ely)f(calls)g(itself)g
(to)g(process)h(the)f(subplans)h(\(it)e(starts)i(with)f(the)g(subplan)
270 2064 y(attached)10 b(to)g Fr(lefttree)p Ft(\).)j(The)e(ne)o(w)f
(top)f(node)h(\(the)g(top)f(node)h(of)g(the)f(left)h(subplan\))f(is)i
(a)f Fr(SeqScan)270 2124 y Ft(node)19 b(and)f(again)h(a)g(tuple)f(has)h
(to)g(be)g(fetched)f(before)g(the)h(node)f(itself)h(can)f(be)h
(processed.)36 b(The)270 2184 y Fp(e)o(xecutor)13 b Ft(calls)g(itself)f
(recursi)o(v)o(ely)f(another)h(time)g(for)g(the)g(subplan)g(attached)h
(to)f Fr(lefttree)f Ft(of)h(the)270 2244 y Fr(SeqScan)g
Ft(node.)345 2324 y(No)o(w)g(the)g(ne)o(w)g(top)h(node)f(is)h(a)f
Fr(Sort)g Ft(node.)k(As)d(a)g(sort)f(has)h(to)f(be)g(done)h(on)f(the)g
(whole)h Fp(r)n(elation)p Ft(,)270 2384 y(the)18 b Fp(e)o(xecutor)h
Ft(starts)f(fetching)f(tuples)h(from)f(the)h Fr(Sort)g
Ft(node')m(s)g(subplan)g(and)g(sorts)h(them)e(into)h(a)270
2444 y(temporary)13 b(relation)h(\(in)f(memory)h(or)f(a)i(\002le\))e
(when)i(the)f Fr(Sort)g Ft(node)g(is)g(visited)h(for)e(the)h(\002rst)g
(time.)270 2503 y(\(Further)e(e)o(xaminations)i(of)g(the)g
Fr(Sort)f Ft(node)h(will)g(always)f(return)g(just)h(one)g(tuple)g(from)
e(the)i(sorted)270 2563 y(temporary)d Fp(r)n(elation)p
Ft(.\))345 2644 y(Ev)o(ery)k(time)g(the)g(processing)g(of)f(the)h
Fr(Sort)g Ft(node)g(needs)g(a)h(ne)o(w)e(tuple)h(the)g
Fp(e)o(xecutor)h Ft(is)f(recur)o(-)270 2703 y(si)o(v)o(ely)i(called)g
(for)f(the)g Fr(SeqScan)g Ft(node)h(attached)g(as)g(subplan.)29
b(The)17 b Fp(r)n(elation)g Ft(\(internally)e(refer)o(-)270
2763 y(enced)i(by)g(the)f(v)o(alue)h(gi)o(v)o(en)f(in)h(the)f
Fr(scanrelid)g Ft(\002eld\))g(is)h(scanned)g(for)f(the)h(ne)o(xt)g
(tuple.)28 b(If)16 b(the)270 2823 y(tuple)h(satis\002es)h(the)f
(quali\002cation)g(gi)o(v)o(en)g(by)g(the)g(tree)g(attached)h(to)f
Fr(qpqual)g Ft(it)g(is)g(handed)h(back,)270 2883 y(otherwise)12
b(the)h(ne)o(xt)f(tuple)h(is)g(fetched)f(until)g(the)g(quali\002cation)
g(is)h(satis\002ed.)k(If)11 b(the)i(last)g(tuple)f(of)g(the)270
2942 y Fp(r)n(elation)g Ft(has)h(been)g(processed)g(a)f
Fr(NULL)g Ft(pointer)g(is)g(returned.)345 3023 y(After)23
b(a)i(tuple)f(has)h(been)f(handed)h(back)f(by)g(the)h
Fr(lefttree)e Ft(of)h(the)h Fr(MergeJoin)e Ft(the)270
3083 y Fr(righttree)16 b Ft(is)h(processed)g(in)g(the)g(same)g(way)m(.)
28 b(If)17 b(both)f(tuples)h(are)g(present)f(the)h(e)o(x)o(ecutor)g
(pro-)270 3142 y(cesses)d(the)e Fr(MergeJoin)f Ft(node.)16
b(Whene)o(v)o(er)c(a)h(ne)o(w)f(tuple)g(from)f(one)h(of)g(the)g
(subplans)h(is)f(needed)h(a)270 3202 y(recursi)o(v)o(e)g(call)f(to)h
(the)g Fp(e)o(xecutor)h Ft(is)f(performed)e(to)i(obtain)f(it.)18
b(If)12 b(a)h Fp(joined)f Ft(tuple)h(could)g(be)g(created)f(it)270
3262 y(is)h(handed)f(back)g(and)h(one)f(complete)g(processing)h(of)f
(the)g Fp(plan)g(tr)n(ee)h Ft(has)g(\002nished.)345 3342
y(No)o(w)j(the)g(described)g(steps)h(are)f(performed)f(once)h(for)g(e)o
(v)o(ery)g(tuple,)h(until)f(a)g Fr(NULL)g Ft(pointer)g(is)270
3402 y(returned)11 b(for)h(the)g(processing)h(of)f(the)g
Fr(MergeJoin)g Ft(node,)g(indicating)g(that)g(we)h(are)f(\002nished.)p
eop
%%Page: 61 61
61 60 bop 198 60 a Fm(3.6.)29 b(EXECUT)o(OR)1384 b Ft(61)243
3011 y @beginspecial 135 @llx 135 @lly 477 @urx 656 @ury
3420 @rwi @setspecial
%%BeginDocument: figures/plan.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
116.0 655.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 315 2025 m 1215 2025 l 1215 2790 l 315 2790 l cp gs col-1 s gr 
% Polyline
n 315 2250 m 1215 2250 l gs col-1 s gr 
% Polyline
n 315 2520 m 1215 2520 l gs col-1 s gr 
% Polyline
n 945 2250 m 945 2790 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
495 2205 m
gs 1 -1 sc (SeqScan) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 2700 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
675 2475 m
gs 1 -1 sc  90.0 rot (. . . ) col-1 sh gr
% Polyline
n 630 3150 m 1530 3150 l 1530 3915 l 630 3915 l cp gs col-1 s gr 
% Polyline
n 630 3375 m 1530 3375 l gs col-1 s gr 
% Polyline
n 630 3645 m 1530 3645 l gs col-1 s gr 
% Polyline
n 1260 3375 m 1260 3915 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
720 3825 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
990 3600 m
gs 1 -1 sc  90.0 rot (. . . ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
945 3330 m
gs 1 -1 sc (Sort) col-1 sh gr
% Polyline
gs  clippath
1110 3003 m 1080 3123 l 1050 3003 l 1050 3165 l 1110 3165 l  cp clip
n 1080 2655 m 1080 3150 l gs col-1 s gr gr

% arrowhead
n 1110 3003 m 1080 3123 l 1050 3003 l 1080 3003 l 1110 3003 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1425 4128 m 1395 4248 l 1365 4128 l 1365 4290 l 1425 4290 l  cp clip
n 1395 3780 m 1395 4275 l gs col-1 s gr gr

% arrowhead
n 1425 4128 m 1395 4248 l 1365 4128 l 1395 4128 l 1425 4128 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 945 4500 m 1845 4500 l gs col-1 s gr 
% Polyline
n 945 4770 m 1845 4770 l gs col-1 s gr 
% Polyline
n 1575 5310 m 1575 5580 l gs col-1 s gr 
% Polyline
n 945 4275 m 1845 4275 l 1845 5580 l 945 5580 l cp gs col-1 s gr 
% Polyline
n 945 5040 m 1845 5040 l gs col-1 s gr 
% Polyline
n 945 5310 m 1845 5310 l gs col-1 s gr 
% Polyline
n 1845 5310 m 1575 5580 l gs col-1 s gr 
% Polyline
n 1575 5310 m 1845 5580 l gs col-1 s gr 
% Polyline
n 1575 4500 m 1575 5040 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1125 4455 m
gs 1 -1 sc (SeqScan) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1305 4725 m
gs 1 -1 sc  90.0 rot (. . . ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1035 5490 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1035 4950 m
gs 1 -1 sc (qpqual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1035 5220 m
gs 1 -1 sc (scanrelid:  1) col-1 sh gr
% Polyline
n 4590 5400 m 4590 5670 l gs col-1 s gr 
% Polyline
n 4320 5400 m 4860 5400 l 4860 5670 l 4320 5670 l cp gs col-1 s gr 
% Polyline
n 5355 5400 m 5355 5670 l gs col-1 s gr 
% Polyline
n 5085 5400 m 5625 5400 l 5625 5670 l 5085 5670 l cp gs col-1 s gr 
% Polyline
n 5355 5400 m 5625 5670 l gs col-1 s gr 
% Polyline
n 5625 5400 m 5355 5670 l gs col-1 s gr 
% Polyline
n 2430 855 m 2430 1125 l gs col-1 s gr 
% Polyline
n 2430 855 m 2700 1125 l gs col-1 s gr 
% Polyline
n 2700 855 m 2430 1125 l gs col-1 s gr 
% Polyline
n 2160 855 m 2700 855 l 2700 1125 l 2160 1125 l cp gs col-1 s gr 
% Polyline
n 1575 2025 m 2475 2025 l 2475 2790 l 1575 2790 l cp gs col-1 s gr 
% Polyline
n 1575 2250 m 2475 2250 l gs col-1 s gr 
% Polyline
n 1575 2520 m 2475 2520 l gs col-1 s gr 
% Polyline
n 2205 2250 m 2205 2790 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1755 2205 m
gs 1 -1 sc (SeqScan) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1665 2700 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1935 2475 m
gs 1 -1 sc  90.0 rot (. . . ) col-1 sh gr
% Polyline
n 1890 3150 m 2790 3150 l 2790 3915 l 1890 3915 l cp gs col-1 s gr 
% Polyline
n 1890 3375 m 2790 3375 l gs col-1 s gr 
% Polyline
n 1890 3645 m 2790 3645 l gs col-1 s gr 
% Polyline
n 2520 3375 m 2520 3915 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1980 3825 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2250 3600 m
gs 1 -1 sc  90.0 rot (. . . ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2205 3330 m
gs 1 -1 sc (Sort) col-1 sh gr
% Polyline
n 3105 225 m 3645 225 l 3645 495 l 3105 495 l cp gs col-1 s gr 
% Polyline
n 3375 225 m 3375 495 l gs col-1 s gr 
% Polyline
n 3915 225 m 4455 225 l 4455 495 l 3915 495 l cp gs col-1 s gr 
% Polyline
n 4185 225 m 4185 495 l gs col-1 s gr 
% Polyline
n 4455 495 m 4185 225 l gs col-1 s gr 
% Polyline
n 4455 225 m 4185 495 l gs col-1 s gr 
% Polyline
n 3240 945 m 4140 945 l 4140 1710 l 3240 1710 l cp gs col-1 s gr 
% Polyline
n 3240 1170 m 4140 1170 l gs col-1 s gr 
% Polyline
n 3240 1440 m 4140 1440 l gs col-1 s gr 
% Polyline
n 3870 1170 m 3870 1710 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3555 1125 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3330 1620 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3330 1350 m
gs 1 -1 sc (resdom) col-1 sh gr
% Polyline
n 4590 945 m 5490 945 l 5490 1710 l 4590 1710 l cp gs col-1 s gr 
% Polyline
n 4590 1170 m 5490 1170 l gs col-1 s gr 
% Polyline
n 4590 1440 m 5490 1440 l gs col-1 s gr 
% Polyline
n 5220 1170 m 5220 1710 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4905 1125 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4680 1620 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4680 1350 m
gs 1 -1 sc (resdom) col-1 sh gr
% Polyline
n 2655 6885 m 2655 7155 l gs col-1 s gr 
% Polyline
n 2385 6885 m 2925 6885 l 2925 7155 l 2385 7155 l cp gs col-1 s gr 
% Polyline
n 3420 6885 m 3420 7155 l gs col-1 s gr 
% Polyline
n 3150 6885 m 3690 6885 l 3690 7155 l 3150 7155 l cp gs col-1 s gr 
% Polyline
n 3420 6885 m 3690 7155 l gs col-1 s gr 
% Polyline
n 3690 6885 m 3420 7155 l gs col-1 s gr 
% Polyline
gs  clippath
4938 5505 m 5058 5535 l 4938 5565 l 5100 5565 l 5100 5505 l  cp clip
n 4725 5535 m 5085 5535 l gs col-1 s gr gr

% arrowhead
n 4938 5505 m 5058 5535 l 4938 5565 l 4938 5535 l 4938 5505 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 4725 5940 m 5625 5940 l 5625 6705 l 4725 6705 l cp gs col-1 s gr 
% Polyline
gs  clippath
2013 960 m 2133 990 l 2013 1020 l 2175 1020 l 2175 960 l  cp clip
n 1395 990 m 2160 990 l gs col-1 s gr gr

% arrowhead
n 2013 960 m 2133 990 l 2013 1020 l 2013 990 l 2013 960 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 315 855 m 1530 855 l gs col-1 s gr 
% Polyline
n 315 1125 m 1530 1125 l gs col-1 s gr 
% Polyline
n 315 1395 m 1530 1395 l gs col-1 s gr 
% Polyline
n 315 585 m 1530 585 l gs col-1 s gr 
% Polyline
n 315 225 m 1530 225 l gs col-1 s gr 
% Polyline
n 2835 4770 m 3105 5040 l gs col-1 s gr 
% Polyline
n 3105 4770 m 2835 5040 l gs col-1 s gr 
% Polyline
gs  clippath
2370 3003 m 2340 3123 l 2310 3003 l 2310 3165 l 2370 3165 l  cp clip
n 2340 2655 m 2340 3150 l gs col-1 s gr gr

% arrowhead
n 2370 3003 m 2340 3123 l 2310 3003 l 2340 3003 l 2370 3003 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2685 4128 m 2655 4248 l 2625 4128 l 2625 4290 l 2685 4290 l  cp clip
n 2655 3780 m 2655 4275 l gs col-1 s gr gr

% arrowhead
n 2685 4128 m 2655 4248 l 2625 4128 l 2655 4128 l 2685 4128 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2205 4500 m 3105 4500 l gs col-1 s gr 
% Polyline
n 2205 4770 m 3105 4770 l gs col-1 s gr 
% Polyline
n 2835 5310 m 2835 5580 l gs col-1 s gr 
% Polyline
n 2205 4275 m 3105 4275 l 3105 5580 l 2205 5580 l cp gs col-1 s gr 
% Polyline
n 2205 5040 m 3105 5040 l gs col-1 s gr 
% Polyline
n 2205 5310 m 3105 5310 l gs col-1 s gr 
% Polyline
n 3105 5310 m 2835 5580 l gs col-1 s gr 
% Polyline
n 2835 5310 m 3105 5580 l gs col-1 s gr 
% Polyline
n 2835 4500 m 2835 5040 l gs col-1 s gr 
% Polyline
gs  clippath
3768 330 m 3888 360 l 3768 390 l 3930 390 l 3930 330 l  cp clip
n 3510 360 m 3915 360 l gs col-1 s gr gr

% arrowhead
n 3768 330 m 3888 360 l 3768 390 l 3768 360 l 3768 330 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 4500 2250 m 5580 2250 l gs col-1 s gr 
% Polyline
n 3150 2250 m 4230 2250 l gs col-1 s gr 
% Polyline
n 3150 2025 m 4230 2025 l 4230 2520 l 3150 2520 l cp gs col-1 s gr 
% Polyline
n 4500 2025 m 5580 2025 l 5580 2520 l 4500 2520 l cp gs col-1 s gr 
% Polyline
n 3240 2835 m 4140 2835 l 4140 3600 l 3240 3600 l cp gs col-1 s gr 
% Polyline
n 3240 3060 m 4140 3060 l gs col-1 s gr 
% Polyline
n 3240 3330 m 4140 3330 l gs col-1 s gr 
% Polyline
n 4590 2835 m 5490 2835 l 5490 3600 l 4590 3600 l cp gs col-1 s gr 
% Polyline
n 4590 3060 m 5490 3060 l gs col-1 s gr 
% Polyline
n 4590 3330 m 5490 3330 l gs col-1 s gr 
% Polyline
n 4725 6165 m 5625 6165 l gs col-1 s gr 
% Polyline
n 4725 6435 m 5625 6435 l gs col-1 s gr 
% Polyline
n 3600 6165 m 4500 6165 l gs col-1 s gr 
% Polyline
n 3600 6435 m 4500 6435 l gs col-1 s gr 
% Polyline
n 3600 5940 m 4500 5940 l 4500 6705 l 3600 6705 l cp gs col-1 s gr 
% Polyline
n 945 6165 m 1935 6165 l gs col-1 s gr 
% Polyline
n 945 6435 m 1935 6435 l gs col-1 s gr 
% Polyline
n 945 6705 m 1935 6705 l gs col-1 s gr 
% Polyline
n 945 5940 m 1935 5940 l 1935 6975 l 945 6975 l cp gs col-1 s gr 
% Polyline
n 1665 6975 m 1665 6435 l gs col-1 s gr 
% Polyline
gs  clippath
3003 6990 m 3123 7020 l 3003 7050 l 3165 7050 l 3165 6990 l  cp clip
n 2790 7020 m 3150 7020 l gs col-1 s gr gr

% arrowhead
n 3003 6990 m 3123 7020 l 3003 7050 l 3003 7020 l 3003 6990 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2385 6165 m 3150 6165 l gs col-1 s gr 
% Polyline
n 2385 6435 m 3150 6435 l gs col-1 s gr 
% Polyline
n 2385 5940 m 3150 5940 l 3150 6705 l 2385 6705 l cp gs col-1 s gr 
% Polyline
n 1485 7695 m 2385 7695 l gs col-1 s gr 
% Polyline
n 1485 7965 m 2385 7965 l gs col-1 s gr 
% Polyline
n 2790 7695 m 3690 7695 l gs col-1 s gr 
% Polyline
n 2790 7470 m 3690 7470 l 3690 7965 l 2790 7965 l cp gs col-1 s gr 
% Polyline
n 1485 7470 m 2385 7470 l 2385 8235 l 1485 8235 l cp gs col-1 s gr 
% Polyline
n 3375 4275 m 4365 4275 l gs col-1 s gr 
% Polyline
n 3375 4545 m 4365 4545 l gs col-1 s gr 
% Polyline
n 3375 4815 m 4365 4815 l gs col-1 s gr 
% Polyline
n 3375 4050 m 4365 4050 l 4365 5085 l 3375 5085 l cp gs col-1 s gr 
% Polyline
n 4095 5085 m 4095 4545 l gs col-1 s gr 
% Polyline
n 4815 4275 m 5580 4275 l gs col-1 s gr 
% Polyline
n 4815 4545 m 5580 4545 l gs col-1 s gr 
% Polyline
n 4815 4050 m 5580 4050 l 5580 4815 l 4815 4815 l cp gs col-1 s gr 
% Polyline
n 315 0 m 1530 0 l 1530 1665 l 315 1665 l cp gs col-1 s gr 
% Polyline
n 1260 225 m 1260 1665 l gs col-1 s gr 
% Open spline
gs  clippath
750 1878 m 720 1998 l 690 1878 l 690 2040 l 750 2040 l  cp clip
n 1395.0 1260.0 m 1462.5 1260.0 l
	1462.5 1260.0 1530.0 1260.0 1597.5 1260.0 DrawSplineSection
	1597.5 1260.0 1665.0 1260.0 1665.0 1327.5 DrawSplineSection
	1665.0 1327.5 1665.0 1395.0 1665.0 1530.0 DrawSplineSection
	1665.0 1530.0 1665.0 1665.0 1665.0 1732.5 DrawSplineSection
	1665.0 1732.5 1665.0 1800.0 1597.5 1800.0 DrawSplineSection
	1597.5 1800.0 1530.0 1800.0 1192.5 1800.0 DrawSplineSection
	1192.5 1800.0 855.0 1800.0 787.5 1800.0 DrawSplineSection
	787.5 1800.0 720.0 1800.0 720.0 1912.5 DrawSplineSection
	720.0 2025.0 l  gs col-1 s gr
 gr

% arrowhead
n 750 1878 m 720 1998 l 690 1878 l 720 1878 l 750 1878 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1547 5834 m 1454 5917 l 1497 5801 l 1407 5936 l 1457 5969 l  cp clip
n 1710.0 4905.0 m 1800.0 4905.0 l
	1800.0 4905.0 1890.0 4905.0 1957.5 4905.0 DrawSplineSection
	1957.5 4905.0 2025.0 4905.0 2025.0 4995.0 DrawSplineSection
	2025.0 4995.0 2025.0 5085.0 2025.0 5355.0 DrawSplineSection
	2025.0 5355.0 2025.0 5625.0 2025.0 5692.5 DrawSplineSection
	2025.0 5692.5 2025.0 5760.0 1957.5 5760.0 DrawSplineSection
	1957.5 5760.0 1890.0 5760.0 1755.0 5760.0 DrawSplineSection
	1755.0 5760.0 1620.0 5760.0 1575.0 5782.5 DrawSplineSection
	1575.0 5782.5 1530.0 5805.0 1485.0 5872.5 DrawSplineSection
	1440.0 5940.0 l  gs col-1 s gr
 gr

% arrowhead
n 1547 5834 m 1454 5917 l 1497 5801 l 1522 5818 l 1547 5834 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2055 1878 m 2025 1998 l 1995 1878 l 1995 2040 l 2055 2040 l  cp clip
n 1395.0 1530.0 m 1642.5 1530.0 l
	1642.5 1530.0 1890.0 1530.0 1957.5 1530.0 DrawSplineSection
	1957.5 1530.0 2025.0 1530.0 2025.0 1620.0 DrawSplineSection
	2025.0 1620.0 2025.0 1710.0 2025.0 1867.5 DrawSplineSection
	2025.0 2025.0 l  gs col-1 s gr
 gr

% arrowhead
n 2055 1878 m 2025 1998 l 1995 1878 l 2025 1878 l 2055 1878 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
5229 5800 m 5179 5913 l 5170 5790 l 5143 5950 l 5202 5960 l  cp clip
n 5220.0 5535.0 m 5220.0 5602.5 l
	5220.0 5602.5 5220.0 5670.0 5197.5 5805.0 DrawSplineSection
	5175.0 5940.0 l  gs col-1 s gr
 gr

% arrowhead
n 5229 5800 m 5179 5913 l 5170 5790 l 5199 5795 l 5229 5800 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4175 5857 m 4069 5920 l 4133 5815 l 4018 5929 l 4061 5972 l  cp clip
n 4455.0 5535.0 m 4455.0 5647.5 l
	4455.0 5647.5 4455.0 5760.0 4320.0 5782.5 DrawSplineSection
	4320.0 5782.5 4185.0 5805.0 4117.5 5872.5 DrawSplineSection
	4050.0 5940.0 l  gs col-1 s gr
 gr

% arrowhead
n 4175 5857 m 4069 5920 l 4133 5815 l 4154 5836 l 4175 5857 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4620 5253 m 4590 5373 l 4560 5253 l 4560 5415 l 4620 5415 l  cp clip
n 4230.0 4950.0 m 4342.5 4950.0 l
	4342.5 4950.0 4455.0 4950.0 4522.5 4950.0 DrawSplineSection
	4522.5 4950.0 4590.0 4950.0 4590.0 5017.5 DrawSplineSection
	4590.0 5017.5 4590.0 5085.0 4590.0 5242.5 DrawSplineSection
	4590.0 5400.0 l  gs col-1 s gr
 gr

% arrowhead
n 4620 5253 m 4590 5373 l 4560 5253 l 4590 5253 l 4620 5253 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3843 3902 m 3859 4024 l 3788 3925 l 3848 4075 l 3903 4053 l  cp clip
n 2295.0 990.0 m 2340.0 1170.0 l
	2340.0 1170.0 2385.0 1350.0 2587.5 1485.0 DrawSplineSection
	2587.5 1485.0 2790.0 1620.0 2857.5 2677.5 DrawSplineSection
	2857.5 2677.5 2925.0 3735.0 3352.5 3780.0 DrawSplineSection
	3352.5 3780.0 3780.0 3825.0 3825.0 3937.5 DrawSplineSection
	3870.0 4050.0 l  gs col-1 s gr
 gr

% arrowhead
n 3843 3902 m 3859 4024 l 3788 3925 l 3815 3914 l 3843 3902 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2958 330 m 3078 360 l 2958 390 l 3120 390 l 3120 330 l  cp clip
n 1395.0 720.0 m 1552.5 720.0 l
	1552.5 720.0 1710.0 720.0 1845.0 540.0 DrawSplineSection
	1845.0 540.0 1980.0 360.0 2542.5 360.0 DrawSplineSection
	3105.0 360.0 l  gs col-1 s gr
 gr

% arrowhead
n 2958 330 m 3078 360 l 2958 390 l 2958 360 l 2958 330 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3607 820 m 3670 925 l 3565 862 l 3679 977 l 3722 934 l  cp clip
n 3240.0 360.0 m 3307.5 495.0 l
	3307.5 495.0 3375.0 630.0 3532.5 787.5 DrawSplineSection
	3690.0 945.0 l  gs col-1 s gr
 gr

% arrowhead
n 3607 820 m 3670 925 l 3565 862 l 3586 841 l 3607 820 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4957 820 m 5020 925 l 4915 862 l 5029 977 l 5072 934 l  cp clip
n 4050.0 360.0 m 4095.0 495.0 l
	4095.0 495.0 4140.0 630.0 4455.0 652.5 DrawSplineSection
	4455.0 652.5 4770.0 675.0 4905.0 810.0 DrawSplineSection
	5040.0 945.0 l  gs col-1 s gr
 gr

% arrowhead
n 4957 820 m 5020 925 l 4915 862 l 4936 841 l 4957 820 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3802 1925 m 3706 2003 l 3754 1889 l 3657 2019 l 3705 2055 l  cp clip
n 4005.0 1305.0 m 4095.0 1305.0 l
	4095.0 1305.0 4185.0 1305.0 4230.0 1305.0 DrawSplineSection
	4230.0 1305.0 4275.0 1305.0 4275.0 1372.5 DrawSplineSection
	4275.0 1372.5 4275.0 1440.0 4275.0 1575.0 DrawSplineSection
	4275.0 1575.0 4275.0 1710.0 4275.0 1777.5 DrawSplineSection
	4275.0 1777.5 4275.0 1845.0 4207.5 1845.0 DrawSplineSection
	4207.5 1845.0 4140.0 1845.0 4050.0 1845.0 DrawSplineSection
	4050.0 1845.0 3960.0 1845.0 3892.5 1845.0 DrawSplineSection
	3892.5 1845.0 3825.0 1845.0 3757.5 1935.0 DrawSplineSection
	3690.0 2025.0 l  gs col-1 s gr
 gr

% arrowhead
n 3802 1925 m 3706 2003 l 3754 1889 l 3778 1907 l 3802 1925 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
5152 1925 m 5056 2003 l 5104 1889 l 5007 2019 l 5055 2055 l  cp clip
n 5355.0 1305.0 m 5445.0 1305.0 l
	5445.0 1305.0 5535.0 1305.0 5580.0 1305.0 DrawSplineSection
	5580.0 1305.0 5625.0 1305.0 5625.0 1372.5 DrawSplineSection
	5625.0 1372.5 5625.0 1440.0 5625.0 1575.0 DrawSplineSection
	5625.0 1575.0 5625.0 1710.0 5625.0 1777.5 DrawSplineSection
	5625.0 1777.5 5625.0 1845.0 5557.5 1845.0 DrawSplineSection
	5557.5 1845.0 5490.0 1845.0 5400.0 1845.0 DrawSplineSection
	5400.0 1845.0 5310.0 1845.0 5242.5 1845.0 DrawSplineSection
	5242.5 1845.0 5175.0 1845.0 5107.5 1935.0 DrawSplineSection
	5040.0 2025.0 l  gs col-1 s gr
 gr

% arrowhead
n 5152 1925 m 5056 2003 l 5104 1889 l 5128 1907 l 5152 1925 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3815 2752 m 3709 2815 l 3773 2710 l 3658 2824 l 3701 2867 l  cp clip
n 4005.0 1575.0 m 4140.0 1575.0 l
	4140.0 1575.0 4275.0 1575.0 4320.0 1575.0 DrawSplineSection
	4320.0 1575.0 4365.0 1575.0 4365.0 1620.0 DrawSplineSection
	4365.0 1620.0 4365.0 1665.0 4365.0 2092.5 DrawSplineSection
	4365.0 2092.5 4365.0 2520.0 4365.0 2610.0 DrawSplineSection
	4365.0 2610.0 4365.0 2700.0 4297.5 2700.0 DrawSplineSection
	4297.5 2700.0 4230.0 2700.0 4027.5 2700.0 DrawSplineSection
	4027.5 2700.0 3825.0 2700.0 3757.5 2767.5 DrawSplineSection
	3690.0 2835.0 l  gs col-1 s gr
 gr

% arrowhead
n 3815 2752 m 3709 2815 l 3773 2710 l 3794 2731 l 3815 2752 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
5165 2752 m 5059 2815 l 5123 2710 l 5008 2824 l 5051 2867 l  cp clip
n 5355.0 1575.0 m 5467.5 1575.0 l
	5467.5 1575.0 5580.0 1575.0 5647.5 1575.0 DrawSplineSection
	5647.5 1575.0 5715.0 1575.0 5715.0 1620.0 DrawSplineSection
	5715.0 1620.0 5715.0 1665.0 5715.0 2092.5 DrawSplineSection
	5715.0 2092.5 5715.0 2520.0 5715.0 2610.0 DrawSplineSection
	5715.0 2610.0 5715.0 2700.0 5647.5 2700.0 DrawSplineSection
	5647.5 2700.0 5580.0 2700.0 5377.5 2700.0 DrawSplineSection
	5377.5 2700.0 5175.0 2700.0 5107.5 2767.5 DrawSplineSection
	5040.0 2835.0 l  gs col-1 s gr
 gr

% arrowhead
n 5165 2752 m 5059 2815 l 5123 2710 l 5144 2731 l 5165 2752 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2238 6270 m 2358 6300 l 2238 6330 l 2400 6330 l 2400 6270 l  cp clip
n 1800.0 6570.0 m 1935.0 6570.0 l
	1935.0 6570.0 2070.0 6570.0 2070.0 6435.0 DrawSplineSection
	2070.0 6435.0 2070.0 6300.0 2227.5 6300.0 DrawSplineSection
	2385.0 6300.0 l  gs col-1 s gr
 gr

% arrowhead
n 2238 6270 m 2358 6300 l 2238 6330 l 2238 6300 l 2238 6270 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2238 6990 m 2358 7020 l 2238 7050 l 2400 7050 l 2400 6990 l  cp clip
n 1800.0 6840.0 m 1912.5 6840.0 l
	1912.5 6840.0 2025.0 6840.0 2047.5 6930.0 DrawSplineSection
	2047.5 6930.0 2070.0 7020.0 2227.5 7020.0 DrawSplineSection
	2385.0 7020.0 l  gs col-1 s gr
 gr

% arrowhead
n 2238 6990 m 2358 7020 l 2238 7050 l 2238 7020 l 2238 6990 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3298 7332 m 3245 7443 l 3239 7320 l 3208 7479 l 3266 7491 l  cp clip
n 3285.0 7020.0 m 3285.0 7132.5 l
	3285.0 7132.5 3285.0 7245.0 3262.5 7357.5 DrawSplineSection
	3240.0 7470.0 l  gs col-1 s gr
 gr

% arrowhead
n 3298 7332 m 3245 7443 l 3239 7320 l 3269 7326 l 3298 7332 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2069 7402 m 1956 7453 l 2031 7355 l 1905 7456 l 1942 7503 l  cp clip
n 2520.0 7020.0 m 2520.0 7132.5 l
	2520.0 7132.5 2520.0 7245.0 2340.0 7267.5 DrawSplineSection
	2340.0 7267.5 2160.0 7290.0 2047.5 7380.0 DrawSplineSection
	1935.0 7470.0 l  gs col-1 s gr
 gr

% arrowhead
n 2069 7402 m 1956 7453 l 2031 7355 l 2050 7378 l 2069 7402 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4668 4380 m 4788 4410 l 4668 4440 l 4830 4440 l 4830 4380 l  cp clip
n 4230.0 4680.0 m 4365.0 4680.0 l
	4365.0 4680.0 4500.0 4680.0 4500.0 4545.0 DrawSplineSection
	4500.0 4545.0 4500.0 4410.0 4657.5 4410.0 DrawSplineSection
	4815.0 4410.0 l  gs col-1 s gr
 gr

% arrowhead
n 4668 4380 m 4788 4410 l 4668 4440 l 4668 4410 l 4668 4380 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
405 1035 m
gs 1 -1 sc (mergeclauses) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 1305 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 1575 m
gs 1 -1 sc (righttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 765 m
gs 1 -1 sc (targetList) col-1 sh gr
/Times-Roman ff 150.00 scf sf
810 495 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2385 4455 m
gs 1 -1 sc (SeqScan) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 4725 m
gs 1 -1 sc  90.0 rot (. . . ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2295 5490 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2295 4950 m
gs 1 -1 sc (qpqual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2295 5220 m
gs 1 -1 sc (scanrelid:  2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4815 2205 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4590 2430 m
gs 1 -1 sc (resname: pno) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3465 2205 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 2430 m
gs 1 -1 sc (resname: sname) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3510 3015 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4860 3015 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4995 6120 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4770 6615 m
gs 1 -1 sc (varattno:  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4770 6345 m
gs 1 -1 sc (varno: 65000) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3870 6120 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3645 6615 m
gs 1 -1 sc (varattno:  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3645 6345 m
gs 1 -1 sc (varno: 65001) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4635 3510 m
gs 1 -1 sc (varattno:  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4635 3240 m
gs 1 -1 sc (varno: 65000) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3285 3240 m
gs 1 -1 sc (varno: 65001) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3285 3510 m
gs 1 -1 sc (varattno:  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
585 180 m
gs 1 -1 sc (MergeJoin) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1035 6345 m
gs 1 -1 sc (opType:  OP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1035 6870 m
gs 1 -1 sc (args) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1305 6120 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2610 6120 m
gs 1 -1 sc (Oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2475 6345 m
gs 1 -1 sc (opno: 521) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2475 6615 m
gs 1 -1 sc (opid:  147) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1755 7650 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 7875 m
gs 1 -1 sc (varno:     1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 7650 m
gs 1 -1 sc (Const) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 8145 m
gs 1 -1 sc (varattno  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3465 4455 m
gs 1 -1 sc (opType:  OP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3465 4980 m
gs 1 -1 sc (args) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3735 4230 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
5040 4230 m
gs 1 -1 sc (Oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4905 4455 m
gs 1 -1 sc (opno:  96) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4905 4725 m
gs 1 -1 sc (opid:   65) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2835 7875 m
gs 1 -1 sc (constvalue: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1035 6630 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3465 4740 m
gs 1 -1 sc (oper) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 681 3120 a(Figure)12 b(3.6:)j Fp(Plan)e
Ft(for)e(query)h(of)g(e)o(xample)h(3.1)p eop
%%Page: 62 62
62 61 bop 270 60 a Ft(62)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Fi(3.7)71 b(The)18 b(Realization)f(of)g(the)h(Ha)n(ving)f(Clause)
270 354 y Ft(The)h Fp(having)g(clause)g Ft(has)g(been)g(designed)g(in)g
(SQL)g(to)f(be)h(able)g(to)g(use)g(the)g(results)f(of)h
Fp(aggr)n(e)n(gate)270 414 y(functions)12 b Ft(within)g(a)h(query)e
(quali\002cation.)k(The)e(handling)f(of)g(the)h Fp(having)f(clause)g
Ft(is)h(v)o(ery)f(similar)g(to)270 474 y(the)h(handling)f(of)h(the)g
Fp(wher)n(e)h(clause)p Ft(.)k(Both)13 b(are)g(formulas)f(in)h(\002rst)g
(order)f(logic)h(\(FOL\))f(that)h(ha)o(v)o(e)g(to)270
534 y(e)o(v)o(aluate)f(to)g(true)g(for)g(a)g(certain)g(object)g(to)h
(be)f(handed)g(back:)345 648 y Fo(\017)25 b Ft(The)13
b(formula)f(gi)o(v)o(en)g(in)h(the)g Fp(wher)n(e)h(clause)f
Ft(is)g(e)o(v)o(aluated)f(for)g(e)o(v)o(ery)h(tuple.)k(If)12
b(the)h(e)o(v)o(aluation)395 707 y(returns)18 b Fr(true)i
Ft(the)f(tuple)g(is)h(returned,)h(e)o(v)o(ery)e(tuple)g(not)g
(satisfying)h(the)f(quali\002cation)g(is)395 767 y(ignored.)345
886 y Fo(\017)25 b Ft(In)10 b(the)h(case)h(of)e Fp(gr)n(oups)i
Ft(the)f Fp(having)f(clause)i Ft(is)f(e)o(v)o(aluated)f(for)g(e)o(v)o
(ery)h(group.)k(If)10 b(the)h(e)o(v)o(aluation)395 945
y(returns)g Fr(true)h Ft(the)h(group)e(is)i(taken)f(into)g(account)g
(otherwise)g(it)g(is)h(ignored.)270 1114 y Fh(3.7.1)59
b(Ho)o(w)15 b(Aggr)o(egate)e(Functions)i(ar)o(e)f(Implemented)270
1216 y Ft(Before)g(we)h(can)g(describe)f(ho)o(w)g(the)h
Fp(having)f(clause)h Ft(is)g(implemented)f(we)g(will)h(ha)o(v)o(e)g(a)f
(look)h(at)f(the)270 1276 y(implementation)h(of)g Fp(aggr)n(e)n(gate)g
(functions)h Ft(as)h(long)e(as)i(the)o(y)f(just)g(appear)f(in)h(the)g
Fp(tar)n(getlist)p Ft(.)26 b(Note)270 1336 y(that)12
b Fp(aggr)n(e)n(gate)g(functions)g Ft(are)g(applied)g(to)g(groups)h(so)
f(the)h(query)e(must)i(contain)f(a)g Fp(gr)n(oup)h(clause)p
Ft(.)270 1484 y Fn(Example)g(3.2)25 b Ft(Here)18 b(is)g(an)g(e)o
(xample)g(of)g(the)g(usage)g(of)g(the)g Fp(aggr)n(e)n(gate)f(function)h
Fr(count)f Ft(which)270 1544 y(counts)c(the)h(number)e(of)h(part)g
(numbers)g(\()p Fr(pno)p Ft(\))f(of)h(e)o(v)o(ery)g(group.)18
b(\(The)c(table)f Fr(sells)g Ft(is)g(de\002ned)g(in)270
1604 y(e)o(xample)f(1.1.\))330 1722 y Fr(select)29 b(sno,)g
(count\(pno\))330 1782 y(from)g(sells)330 1842 y(group)g(by)h(sno;)270
1955 y Ft(A)12 b(query)g(like)g(the)g(one)h(in)f(e)o(xample)g(3.2)h(is)
g(processed)g(by)f(the)g(usual)h(stages:)345 2069 y Fo(\017)25
b Ft(the)12 b(parser)g(stage)345 2188 y Fo(\017)25 b
Ft(the)12 b(re)o(write)f(system)345 2306 y Fo(\017)25
b Ft(the)12 b(planner/optimizer)345 2425 y Fo(\017)25
b Ft(the)12 b(e)o(x)o(ecutor)270 2539 y(and)i(in)f(the)g(follo)o(wing)f
(sections)j(we)e(will)g(describe)h(what)f(e)o(v)o(ery)h(stage)g(does)g
(to)f(the)g(query)h(in)f(order)270 2598 y(to)f(obtain)g(the)h
(appropriate)e(result.)270 2757 y Fn(The)h(Parser)i(Stage)270
2860 y Ft(The)h(parser)e(stage)i(b)o(uilds)f(up)g(a)g
Fp(querytr)n(ee)h Ft(containing)f(the)g Fp(wher)n(e)h
Ft(quali\002cation)e(and)h(information)270 2919 y(about)h(the)f
Fp(gr)n(ouping)h Ft(that)f(has)i(to)e(be)h(done)g(\(i.e.)23
b(a)15 b(list)g(of)f(all)h(attrib)o(utes)f(to)h(group)f(for)g(is)h
(attached)270 2979 y(to)e(the)h(\002eld)f Fr(groupClause)p
Ft(\).)18 b(The)c(main)f(dif)o(ference)f(to)h Fp(querytr)n(ees)i
Ft(b)o(uilt)e(up)h(for)e(queries)i(with-)270 3039 y(out)j
Fp(aggr)n(e)n(gate)f(functions)h Ft(is)h(gi)o(v)o(en)f(in)g(the)g
(\002eld)g Fr(hasAggs)g Ft(which)g(is)g(set)h(to)f Fr(true)g
Ft(and)g(in)g(the)270 3099 y Fp(tar)n(getlist)p Ft(.)30
b(The)18 b Fr(expr)e Ft(\002eld)h(of)g(the)g(second)h
Fr(TLE)e Ft(node)i(of)e(the)h Fp(tar)n(getlist)g Ft(sho)o(wn)g(in)g
(\002gure)g(3.7)270 3158 y(does)e(not)f(point)f(directly)h(to)g(a)g
Fr(VAR)g Ft(node)g(b)o(ut)g(to)g(an)g Fr(Aggreg)g Ft(node)g
(representing)g(the)g Fp(aggr)n(e)n(gate)270 3218 y(function)e
Ft(used)g(in)h(the)f(query)m(.)345 3283 y(A)17 b(check)g(is)h(made)f
(that)g(e)o(v)o(ery)g(attrib)o(ute)g(grouped)f(for)h(appears)g(only)g
(without)f(an)i Fp(aggr)n(e)n(gate)270 3342 y(function)12
b Ft(in)h(the)f Fp(tar)n(getlist)h Ft(and)f(that)h(e)o(v)o(ery)f
(attrib)o(ute)g(which)h(appears)g(without)f(an)h Fp(aggr)n(e)n(gate)f
(func-)270 3402 y(tion)g Ft(in)g(the)g Fp(tar)n(getlist)h
Ft(is)f(grouped)g(for)m(.)p eop
%%Page: 63 63
63 62 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(63)393
1754 y @beginspecial 165 @llx 239 @lly 447 @urx 553 @ury
2820 @rwi @setspecial
%%BeginDocument: figures/parse_having.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
155.0 566.0 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1665 720 m 2205 720 l 2205 990 l 1665 990 l cp gs col-1 s gr 
% Polyline
n 1935 720 m 1935 990 l gs col-1 s gr 
% Polyline
n 2475 720 m 3015 720 l 3015 990 l 2475 990 l cp gs col-1 s gr 
% Polyline
n 2745 720 m 2745 990 l gs col-1 s gr 
% Polyline
n 3015 990 m 2745 720 l gs col-1 s gr 
% Polyline
n 3015 720 m 2745 990 l gs col-1 s gr 
% Polyline
n 3690 225 m 4230 225 l 4230 495 l 3690 495 l cp gs col-1 s gr 
% Polyline
n 3960 225 m 3960 495 l gs col-1 s gr 
% Polyline
n 4230 495 m 3960 225 l gs col-1 s gr 
% Polyline
n 4230 225 m 3960 495 l gs col-1 s gr 
% Polyline
n 3690 945 m 4590 945 l gs col-1 s gr 
% Polyline
n 3690 720 m 4590 720 l 4590 1215 l 3690 1215 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4005 900 m
gs 1 -1 sc (RTE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3735 1125 m
gs 1 -1 sc (relname: sells) col-1 sh gr
% Polyline
n 1800 1440 m 2700 1440 l 2700 2205 l 1800 2205 l cp gs col-1 s gr 
% Polyline
n 1800 1665 m 2700 1665 l gs col-1 s gr 
% Polyline
n 1800 1935 m 2700 1935 l gs col-1 s gr 
% Polyline
n 2430 1665 m 2430 2205 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2115 1620 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 2115 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 1845 m
gs 1 -1 sc (resdom) col-1 sh gr
% Polyline
n 3150 1440 m 4050 1440 l 4050 2205 l 3150 2205 l cp gs col-1 s gr 
% Polyline
n 3150 1665 m 4050 1665 l gs col-1 s gr 
% Polyline
n 3150 1935 m 4050 1935 l gs col-1 s gr 
% Polyline
n 3780 1665 m 3780 2205 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3465 1620 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 2115 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 1845 m
gs 1 -1 sc (resdom) col-1 sh gr
% Polyline
n 405 4005 m 945 4005 l 945 4275 l 405 4275 l cp gs col-1 s gr 
% Polyline
n 675 4005 m 675 4275 l gs col-1 s gr 
% Polyline
n 945 4275 m 675 4005 l gs col-1 s gr 
% Polyline
n 945 4005 m 675 4275 l gs col-1 s gr 
% Polyline
n 1125 450 m 1125 1530 l gs col-1 s gr 
% Polyline
n 180 450 m 1395 450 l gs col-1 s gr 
% Polyline
n 180 720 m 1395 720 l gs col-1 s gr 
% Polyline
n 180 990 m 1395 990 l gs col-1 s gr 
% Polyline
n 180 1260 m 1395 1260 l gs col-1 s gr 
% Polyline
n 180 1530 m 1395 1530 l gs col-1 s gr 
% Polyline
n 180 1800 m 1395 1800 l gs col-1 s gr 
% Polyline
n 180 225 m 1395 225 l 1395 2205 l 180 2205 l cp gs col-1 s gr 
% Polyline
n 1125 1800 m 1125 2205 l gs col-1 s gr 
% Polyline
n 1125 990 m 1395 1260 l gs col-1 s gr 
% Polyline
n 1395 990 m 1125 1260 l gs col-1 s gr 
% Polyline
gs  clippath
1518 825 m 1638 855 l 1518 885 l 1680 885 l 1680 825 l  cp clip
n 1260 855 m 1665 855 l gs col-1 s gr gr

% arrowhead
n 1518 825 m 1638 855 l 1518 885 l 1518 855 l 1518 825 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2328 825 m 2448 855 l 2328 885 l 2490 885 l 2490 825 l  cp clip
n 2070 855 m 2475 855 l gs col-1 s gr gr

% arrowhead
n 2328 825 m 2448 855 l 2328 885 l 2328 855 l 2328 825 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3105 2745 m 4095 2745 l gs col-1 s gr 
% Polyline
n 3105 2520 m 4095 2520 l 4095 3015 l 3105 3015 l cp gs col-1 s gr 
% Polyline
n 1755 2745 m 2745 2745 l gs col-1 s gr 
% Polyline
n 1755 2520 m 2745 2520 l 2745 3015 l 1755 3015 l cp gs col-1 s gr 
% Polyline
n 3060 3555 m 4140 3555 l gs col-1 s gr 
% Polyline
n 3060 3825 m 4140 3825 l gs col-1 s gr 
% Polyline
n 3150 4410 m 4050 4410 l 4050 5175 l 3150 5175 l cp gs col-1 s gr 
% Polyline
n 3150 4635 m 4050 4635 l gs col-1 s gr 
% Polyline
n 3150 4905 m 4050 4905 l gs col-1 s gr 
% Polyline
n 3060 3330 m 4140 3330 l 4140 4095 l 3060 4095 l cp gs col-1 s gr 
% Polyline
n 3870 3825 m 3870 4095 l gs col-1 s gr 
% Polyline
n 1800 3330 m 2700 3330 l 2700 4095 l 1800 4095 l cp gs col-1 s gr 
% Polyline
n 1800 3555 m 2700 3555 l gs col-1 s gr 
% Polyline
n 1800 3825 m 2700 3825 l gs col-1 s gr 
% Polyline
n 225 4680 m 1125 4680 l 1125 5175 l 225 5175 l cp gs col-1 s gr 
% Polyline
n 225 4905 m 1125 4905 l gs col-1 s gr 
% Polyline
n 855 4905 m 855 5175 l gs col-1 s gr 
% Open spline
gs  clippath
2167 1315 m 2230 1420 l 2125 1357 l 2239 1472 l 2282 1429 l  cp clip
n 1800.0 855.0 m 1867.5 990.0 l
	1867.5 990.0 1935.0 1125.0 2092.5 1282.5 DrawSplineSection
	2250.0 1440.0 l  gs col-1 s gr
 gr

% arrowhead
n 2167 1315 m 2230 1420 l 2125 1357 l 2146 1336 l 2167 1315 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3517 1315 m 3580 1420 l 3475 1357 l 3589 1472 l 3632 1429 l  cp clip
n 2610.0 855.0 m 2655.0 990.0 l
	2655.0 990.0 2700.0 1125.0 3015.0 1147.5 DrawSplineSection
	3015.0 1147.5 3330.0 1170.0 3465.0 1305.0 DrawSplineSection
	3600.0 1440.0 l  gs col-1 s gr
 gr

% arrowhead
n 3517 1315 m 3580 1420 l 3475 1357 l 3496 1336 l 3517 1315 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3543 330 m 3663 360 l 3543 390 l 3705 390 l 3705 330 l  cp clip
n 1260.0 585.0 m 1462.5 585.0 l
	1462.5 585.0 1665.0 585.0 2070.0 472.5 DrawSplineSection
	2070.0 472.5 2475.0 360.0 3082.5 360.0 DrawSplineSection
	3690.0 360.0 l  gs col-1 s gr
 gr

% arrowhead
n 3543 330 m 3663 360 l 3543 390 l 3543 360 l 3543 330 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4022 627 m 4115 707 l 3995 681 l 4140 754 l 4167 700 l  cp clip
n 3825.0 360.0 m 3847.5 472.5 l
	3847.5 472.5 3870.0 585.0 4005.0 652.5 DrawSplineSection
	4140.0 720.0 l  gs col-1 s gr
 gr

% arrowhead
n 4022 627 m 4115 707 l 3995 681 l 4009 654 l 4022 627 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2343 2402 m 2262 2495 l 2289 2375 l 2216 2520 l 2270 2547 l  cp clip
n 2565.0 1800.0 m 2700.0 1800.0 l
	2700.0 1800.0 2835.0 1800.0 2835.0 2070.0 DrawSplineSection
	2835.0 2070.0 2835.0 2340.0 2587.5 2340.0 DrawSplineSection
	2587.5 2340.0 2340.0 2340.0 2295.0 2430.0 DrawSplineSection
	2250.0 2520.0 l  gs col-1 s gr
 gr

% arrowhead
n 2343 2402 m 2262 2495 l 2289 2375 l 2316 2389 l 2343 2402 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3693 2402 m 3612 2495 l 3639 2375 l 3566 2520 l 3620 2547 l  cp clip
n 3915.0 1800.0 m 4050.0 1800.0 l
	4050.0 1800.0 4185.0 1800.0 4185.0 2070.0 DrawSplineSection
	4185.0 2070.0 4185.0 2340.0 3937.5 2340.0 DrawSplineSection
	3937.5 2340.0 3690.0 2340.0 3645.0 2430.0 DrawSplineSection
	3600.0 2520.0 l  gs col-1 s gr
 gr

% arrowhead
n 3693 2402 m 3612 2495 l 3639 2375 l 3666 2389 l 3693 2402 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2362 3230 m 2266 3308 l 2314 3194 l 2217 3324 l 2265 3360 l  cp clip
n 2565.0 2070.0 m 2767.5 2070.0 l
	2767.5 2070.0 2970.0 2070.0 2970.0 2632.5 DrawSplineSection
	2970.0 2632.5 2970.0 3195.0 2677.5 3172.5 DrawSplineSection
	2677.5 3172.5 2385.0 3150.0 2317.5 3240.0 DrawSplineSection
	2250.0 3330.0 l  gs col-1 s gr
 gr

% arrowhead
n 2362 3230 m 2266 3308 l 2314 3194 l 2338 3212 l 2362 3230 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3712 3230 m 3616 3308 l 3664 3194 l 3567 3324 l 3615 3360 l  cp clip
n 3915.0 2070.0 m 4117.5 2070.0 l
	4117.5 2070.0 4320.0 2070.0 4320.0 2632.5 DrawSplineSection
	4320.0 2632.5 4320.0 3195.0 4027.5 3172.5 DrawSplineSection
	4027.5 3172.5 3735.0 3150.0 3667.5 3240.0 DrawSplineSection
	3600.0 3330.0 l  gs col-1 s gr
 gr

% arrowhead
n 3712 3230 m 3616 3308 l 3664 3194 l 3688 3212 l 3712 3230 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3693 4292 m 3612 4385 l 3639 4265 l 3566 4410 l 3620 4437 l  cp clip
n 4005.0 3960.0 m 3982.5 4072.5 l
	3982.5 4072.5 3960.0 4185.0 3825.0 4207.5 DrawSplineSection
	3825.0 4207.5 3690.0 4230.0 3645.0 4320.0 DrawSplineSection
	3600.0 4410.0 l  gs col-1 s gr
 gr

% arrowhead
n 3693 4292 m 3612 4385 l 3639 4265 l 3666 4279 l 3693 4292 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
305 4028 m 383 4123 l 269 4076 l 399 4173 l 435 4125 l  cp clip
n 1260.0 1395.0 m 1395.0 1395.0 l
	1395.0 1395.0 1530.0 1395.0 1507.5 2047.5 DrawSplineSection
	1507.5 2047.5 1485.0 2700.0 877.5 2767.5 DrawSplineSection
	877.5 2767.5 270.0 2835.0 247.5 3420.0 DrawSplineSection
	247.5 3420.0 225.0 4005.0 315.0 4072.5 DrawSplineSection
	405.0 4140.0 l  gs col-1 s gr
 gr

% arrowhead
n 305 4028 m 383 4123 l 269 4076 l 287 4052 l 305 4028 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
636 4535 m 662 4655 l 582 4562 l 655 4707 l 709 4680 l  cp clip
n 540.0 4140.0 m 540.0 4275.0 l
	540.0 4275.0 540.0 4410.0 607.5 4545.0 DrawSplineSection
	675.0 4680.0 l  gs col-1 s gr
 gr

% arrowhead
n 636 4535 m 662 4655 l 582 4562 l 609 4549 l 636 4535 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1675 1883 m 1780 1819 l 1717 1925 l 1832 1811 l 1789 1768 l  cp clip
n 990.0 5040.0 m 1305.0 4972.5 l
	1305.0 4972.5 1620.0 4905.0 1620.0 3825.0 DrawSplineSection
	1620.0 3825.0 1620.0 2745.0 1620.0 2362.5 DrawSplineSection
	1620.0 2362.5 1620.0 1980.0 1710.0 1890.0 DrawSplineSection
	1800.0 1800.0 l  gs col-1 s gr
 gr

% arrowhead
n 1675 1883 m 1780 1819 l 1717 1925 l 1696 1904 l 1675 1883 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
540 405 m
gs 1 -1 sc (Query) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 630 m
gs 1 -1 sc (rtable) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 900 m
gs 1 -1 sc (targetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 1170 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 1440 m
gs 1 -1 sc (groupClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 1710 m
gs 1 -1 sc (hasAggs:     true) col-1 sh gr
/Times-Roman ff 150.00 scf sf
630 1935 m
gs 1 -1 sc  270.0 rot (. . . ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 2700 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3150 2925 m
gs 1 -1 sc (resname: count) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1845 2925 m
gs 1 -1 sc (resname: sno) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2025 2700 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 4815 m
gs 1 -1 sc (varno:      1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 5085 m
gs 1 -1 sc (varattno:  2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3420 4590 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 3510 m
gs 1 -1 sc (Aggreg) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 4005 m
gs 1 -1 sc (target) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 3735 m
gs 1 -1 sc (aggname: count) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 3735 m
gs 1 -1 sc (varno:      1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 4005 m
gs 1 -1 sc (varattno:  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2070 3510 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 5085 m
gs 1 -1 sc (entry) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 4860 m
gs 1 -1 sc (GroupClause) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 509 1864 a(Figure)11 b(3.7:)16 b Fp(Querytr)n(ee)e
Ft(b)o(uilt)d(up)i(for)e(the)h(query)g(of)g(e)o(xample)h(3.2)198
2091 y Fn(The)f(Rewrite)h(System)198 2200 y Ft(The)19
b(re)o(writing)d(system)j(does)g(not)f(make)f(an)o(y)i(changes)f(to)h
(the)f Fp(querytr)n(ee)h Ft(as)g(long)f(as)g(the)h(query)198
2260 y(in)n(v)o(olv)o(es)12 b(just)g Fp(base)g(tables)p
Ft(.)j(If)c(an)o(y)h Fp(vie)o(ws)h Ft(are)f(present)f(the)h(query)f(is)
h(re)o(written)f(to)g(access)i(the)f(tables)198 2320
y(speci\002ed)h(in)f(the)g Fp(vie)o(w)h(de\002nition)p
Ft(.)198 2499 y Fn(Planner/Optimizer)198 2608 y Ft(Whene)o(v)o(er)d(an)
f Fp(aggr)n(e)n(gate)g(function)g Ft(is)i(in)n(v)o(olv)o(ed)e(in)h(a)g
(query)f(\(which)g(is)h(indicated)f(by)h(the)g Fr(hasAggs)198
2668 y Ft(\003ag)18 b(set)i(to)e Fr(true)p Ft(\))g(the)h(planner)f
(creates)h(a)g Fp(plantr)n(ee)g Ft(whose)g(top)f(node)h(is)g(an)f
Fr(AGG)h Ft(node.)35 b(The)198 2728 y Fp(tar)n(getlist)12
b Ft(is)g(searched)h(for)e Fp(aggr)n(e)n(gate)h(functions)g
Ft(and)g(for)g(e)o(v)o(ery)f(function)h(that)g(is)g(found,)g(a)h
(pointer)198 2788 y(to)h(the)g(corresponding)g Fr(Aggreg)f
Ft(node)h(is)h(added)f(to)g(a)h(list)f(which)g(is)g(\002nally)g
(attached)g(to)g(the)g(\002eld)198 2847 y Fr(aggs)19
b Ft(of)g(the)g Fr(AGG)g Ft(node.)36 b(This)20 b(list)g(is)f(needed)h
(by)f(the)g Fp(e)o(xecutor)h Ft(to)f(kno)o(w)g(which)g
Fp(aggr)n(e)n(gate)198 2907 y(functions)12 b Ft(are)g(present)h(and)f
(ha)o(v)o(e)h(to)f(be)h(handled.)273 2975 y(The)i Fr(AGG)f
Ft(node)g(is)h(follo)o(wed)e(by)h(a)h Fr(GRP)f Ft(node.)21
b(The)15 b(implementation)e(of)h(the)h Fp(gr)n(ouping)e
Ft(logic)198 3035 y(needs)j(a)g(sorted)f(table)g(for)g(its)h(operation)
e(so)i(the)g Fr(GRP)f Ft(node)g(is)h(follo)o(wed)e(by)i(a)f
Fr(SORT)h Ft(node.)25 b(The)198 3095 y Fr(SORT)11 b Ft(operation)f
(gets)h(its)g(tuples)g(from)f(a)i(kind)e(of)h Fr(Scan)f
Ft(node)h(\(if)f(no)h(indices)h(are)e(present)h(this)g(will)198
3155 y(be)16 b(a)f(simple)g Fr(SeqScan)g Ft(node\).)25
b(An)o(y)15 b(quali\002cations)g(present)g(are)h(attached)f(to)g(the)h
Fr(Scan)f Ft(node.)198 3214 y(Figure)d(3.8)g(sho)o(ws)h(the)f
Fp(plan)g Ft(created)h(for)e(the)h(query)g(gi)o(v)o(en)g(in)h(e)o
(xample)f(3.2.)273 3283 y(Note)i(that)g(e)o(v)o(ery)f(node)h(has)h(its)
f(o)o(wn)g Fp(tar)n(getlist)g Ft(which)g(may)g(dif)o(fer)e(from)h(the)h
(one)g(of)g(the)g(node)198 3342 y(abo)o(v)o(e)g(or)f(belo)o(w)m(.)18
b(The)c(\002eld)f Fr(varattno)g Ft(of)g(e)o(v)o(ery)g
Fr(VAR)g Ft(node)g(included)g(in)g(a)h Fp(tar)n(getlist)f
Ft(contains)198 3402 y(a)g(number)e(representing)h(the)g(position)g(of)
g(the)g(attrib)o(ute')m(s)g(v)o(alue)g(in)g(the)h(tuple)f(of)g(the)g
(current)g(node.)p eop
%%Page: 64 64
64 63 bop 270 60 a Ft(64)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)385
2841 y @beginspecial 149 @llx 169 @lly 463 @urx 622 @ury
3140 @rwi @setspecial
%%BeginDocument: figures/plan_having.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
130.0 635.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1665 720 m 2205 720 l 2205 990 l 1665 990 l cp gs col-1 s gr 
% Polyline
n 1935 720 m 1935 990 l gs col-1 s gr 
% Polyline
n 2475 720 m 3015 720 l 3015 990 l 2475 990 l cp gs col-1 s gr 
% Polyline
n 2745 720 m 2745 990 l gs col-1 s gr 
% Polyline
n 3015 990 m 2745 720 l gs col-1 s gr 
% Polyline
n 3015 720 m 2745 990 l gs col-1 s gr 
% Polyline
n 1800 1440 m 2700 1440 l 2700 2205 l 1800 2205 l cp gs col-1 s gr 
% Polyline
n 1800 1665 m 2700 1665 l gs col-1 s gr 
% Polyline
n 1800 1935 m 2700 1935 l gs col-1 s gr 
% Polyline
n 2430 1665 m 2430 2205 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2115 1620 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 2115 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 1845 m
gs 1 -1 sc (resdom) col-1 sh gr
% Polyline
n 3150 1440 m 4050 1440 l 4050 2205 l 3150 2205 l cp gs col-1 s gr 
% Polyline
n 3150 1665 m 4050 1665 l gs col-1 s gr 
% Polyline
n 3150 1935 m 4050 1935 l gs col-1 s gr 
% Polyline
n 3780 1665 m 3780 2205 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3465 1620 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 2115 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 1845 m
gs 1 -1 sc (resdom) col-1 sh gr
% Polyline
n 3510 225 m 4050 225 l 4050 495 l 3510 495 l cp gs col-1 s gr 
% Polyline
n 3780 225 m 3780 495 l gs col-1 s gr 
% Polyline
n 3780 225 m 4050 495 l gs col-1 s gr 
% Polyline
n 4050 225 m 3780 495 l gs col-1 s gr 
% Polyline
gs  clippath
1518 825 m 1638 855 l 1518 885 l 1680 885 l 1680 825 l  cp clip
n 1260 855 m 1665 855 l gs col-1 s gr gr

% arrowhead
n 1518 825 m 1638 855 l 1518 885 l 1518 855 l 1518 825 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2328 825 m 2448 855 l 2328 885 l 2490 885 l 2490 825 l  cp clip
n 2070 855 m 2475 855 l gs col-1 s gr gr

% arrowhead
n 2328 825 m 2448 855 l 2328 885 l 2328 855 l 2328 825 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3105 2745 m 4095 2745 l gs col-1 s gr 
% Polyline
n 3105 2520 m 4095 2520 l 4095 3015 l 3105 3015 l cp gs col-1 s gr 
% Polyline
n 1755 2745 m 2745 2745 l gs col-1 s gr 
% Polyline
n 1755 2520 m 2745 2520 l 2745 3015 l 1755 3015 l cp gs col-1 s gr 
% Polyline
n 3060 3555 m 4140 3555 l gs col-1 s gr 
% Polyline
n 3060 3825 m 4140 3825 l gs col-1 s gr 
% Polyline
n 3150 4410 m 4050 4410 l 4050 5175 l 3150 5175 l cp gs col-1 s gr 
% Polyline
n 3150 4635 m 4050 4635 l gs col-1 s gr 
% Polyline
n 3150 4905 m 4050 4905 l gs col-1 s gr 
% Polyline
n 3060 3330 m 4140 3330 l 4140 4095 l 3060 4095 l cp gs col-1 s gr 
% Polyline
n 3870 3825 m 3870 4095 l gs col-1 s gr 
% Polyline
n 1800 3330 m 2700 3330 l 2700 4095 l 1800 4095 l cp gs col-1 s gr 
% Polyline
n 1800 3555 m 2700 3555 l gs col-1 s gr 
% Polyline
n 1800 3825 m 2700 3825 l gs col-1 s gr 
% Polyline
n 315 450 m 1395 450 l gs col-1 s gr 
% Polyline
n 315 720 m 1395 720 l gs col-1 s gr 
% Polyline
n 315 990 m 1395 990 l gs col-1 s gr 
% Polyline
n 315 1260 m 1395 1260 l gs col-1 s gr 
% Polyline
n 1125 450 m 1125 1620 l gs col-1 s gr 
% Polyline
n 1125 450 m 1125 1530 l gs col-1 s gr 
% Polyline
n 720 4995 m 1800 4995 l gs col-1 s gr 
% Polyline
n 720 5265 m 1800 5265 l gs col-1 s gr 
% Polyline
n 1530 4725 m 1530 5625 l gs col-1 s gr 
% Polyline
n 720 4725 m 1800 4725 l gs col-1 s gr 
% Polyline
n 720 4500 m 1800 4500 l 1800 5625 l 720 5625 l cp gs col-1 s gr 
% Polyline
n 2160 5895 m 3240 5895 l gs col-1 s gr 
% Polyline
n 2160 6165 m 3240 6165 l gs col-1 s gr 
% Polyline
n 2970 5625 m 2970 6525 l gs col-1 s gr 
% Polyline
n 2160 5625 m 3240 5625 l gs col-1 s gr 
% Polyline
n 3600 6795 m 4680 6795 l gs col-1 s gr 
% Polyline
n 3600 7065 m 4680 7065 l gs col-1 s gr 
% Polyline
n 3600 6525 m 4680 6525 l gs col-1 s gr 
% Polyline
n 2160 5400 m 3240 5400 l 3240 6525 l 2160 6525 l cp gs col-1 s gr 
% Polyline
n 4410 6525 m 4410 7380 l gs col-1 s gr 
% Polyline
n 3600 6300 m 4680 6300 l 4680 7380 l 3600 7380 l cp gs col-1 s gr 
% Polyline
n 315 225 m 1395 225 l 1395 1620 l 315 1620 l cp gs col-1 s gr 
% Open spline
gs  clippath
2167 1315 m 2230 1420 l 2125 1357 l 2239 1472 l 2282 1429 l  cp clip
n 1800.0 855.0 m 1867.5 990.0 l
	1867.5 990.0 1935.0 1125.0 2092.5 1282.5 DrawSplineSection
	2250.0 1440.0 l  gs col-1 s gr
 gr

% arrowhead
n 2167 1315 m 2230 1420 l 2125 1357 l 2146 1336 l 2167 1315 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3517 1315 m 3580 1420 l 3475 1357 l 3589 1472 l 3632 1429 l  cp clip
n 2610.0 855.0 m 2655.0 990.0 l
	2655.0 990.0 2700.0 1125.0 3015.0 1147.5 DrawSplineSection
	3015.0 1147.5 3330.0 1170.0 3465.0 1305.0 DrawSplineSection
	3600.0 1440.0 l  gs col-1 s gr
 gr

% arrowhead
n 3517 1315 m 3580 1420 l 3475 1357 l 3496 1336 l 3517 1315 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2343 2402 m 2262 2495 l 2289 2375 l 2216 2520 l 2270 2547 l  cp clip
n 2565.0 1800.0 m 2700.0 1800.0 l
	2700.0 1800.0 2835.0 1800.0 2835.0 2070.0 DrawSplineSection
	2835.0 2070.0 2835.0 2340.0 2587.5 2340.0 DrawSplineSection
	2587.5 2340.0 2340.0 2340.0 2295.0 2430.0 DrawSplineSection
	2250.0 2520.0 l  gs col-1 s gr
 gr

% arrowhead
n 2343 2402 m 2262 2495 l 2289 2375 l 2316 2389 l 2343 2402 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3693 2402 m 3612 2495 l 3639 2375 l 3566 2520 l 3620 2547 l  cp clip
n 3915.0 1800.0 m 4050.0 1800.0 l
	4050.0 1800.0 4185.0 1800.0 4185.0 2070.0 DrawSplineSection
	4185.0 2070.0 4185.0 2340.0 3937.5 2340.0 DrawSplineSection
	3937.5 2340.0 3690.0 2340.0 3645.0 2430.0 DrawSplineSection
	3600.0 2520.0 l  gs col-1 s gr
 gr

% arrowhead
n 3693 2402 m 3612 2495 l 3639 2375 l 3666 2389 l 3693 2402 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3712 3230 m 3616 3308 l 3664 3194 l 3567 3324 l 3615 3360 l  cp clip
n 3915.0 2070.0 m 4117.5 2070.0 l
	4117.5 2070.0 4320.0 2070.0 4320.0 2632.5 DrawSplineSection
	4320.0 2632.5 4320.0 3195.0 4027.5 3172.5 DrawSplineSection
	4027.5 3172.5 3735.0 3150.0 3667.5 3240.0 DrawSplineSection
	3600.0 3330.0 l  gs col-1 s gr
 gr

% arrowhead
n 3712 3230 m 3616 3308 l 3664 3194 l 3688 3212 l 3712 3230 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3693 4292 m 3612 4385 l 3639 4265 l 3566 4410 l 3620 4437 l  cp clip
n 4005.0 3960.0 m 3982.5 4072.5 l
	3982.5 4072.5 3960.0 4185.0 3825.0 4207.5 DrawSplineSection
	3825.0 4207.5 3690.0 4230.0 3645.0 4320.0 DrawSplineSection
	3600.0 4410.0 l  gs col-1 s gr
 gr

% arrowhead
n 3693 4292 m 3612 4385 l 3639 4265 l 3666 4279 l 3693 4292 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2362 3230 m 2266 3308 l 2314 3194 l 2217 3324 l 2265 3360 l  cp clip
n 2565.0 2070.0 m 2767.5 2070.0 l
	2767.5 2070.0 2970.0 2070.0 2970.0 2632.5 DrawSplineSection
	2970.0 2632.5 2970.0 3195.0 2677.5 3172.5 DrawSplineSection
	2677.5 3172.5 2385.0 3150.0 2317.5 3240.0 DrawSplineSection
	2250.0 3330.0 l  gs col-1 s gr
 gr

% arrowhead
n 2362 3230 m 2266 3308 l 2314 3194 l 2338 3212 l 2362 3230 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3363 330 m 3483 360 l 3363 390 l 3525 390 l 3525 330 l  cp clip
n 1260.0 585.0 m 1687.5 585.0 l
	1687.5 585.0 2115.0 585.0 2407.5 472.5 DrawSplineSection
	2407.5 472.5 2700.0 360.0 3105.0 360.0 DrawSplineSection
	3510.0 360.0 l  gs col-1 s gr
 gr

% arrowhead
n 3363 330 m 3483 360 l 3363 390 l 3363 360 l 3363 330 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4277 3628 m 4161 3674 l 4241 3579 l 4110 3675 l 4146 3723 l  cp clip
n 3645.0 360.0 m 3645.0 585.0 l
	3645.0 585.0 3645.0 810.0 4140.0 1102.5 DrawSplineSection
	4140.0 1102.5 4635.0 1395.0 4635.0 2362.5 DrawSplineSection
	4635.0 2362.5 4635.0 3330.0 4387.5 3510.0 DrawSplineSection
	4140.0 3690.0 l  gs col-1 s gr
 gr

% arrowhead
n 4277 3628 m 4161 3674 l 4241 3579 l 4259 3604 l 4277 3628 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2608 5282 m 2679 5382 l 2569 5327 l 2692 5433 l 2731 5387 l  cp clip
n 1665.0 5130.0 m 2025.0 5130.0 l
	2025.0 5130.0 2385.0 5130.0 2542.5 5265.0 DrawSplineSection
	2700.0 5400.0 l  gs col-1 s gr
 gr

% arrowhead
n 2608 5282 m 2679 5382 l 2569 5327 l 2588 5304 l 2608 5282 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1290 4353 m 1260 4473 l 1230 4353 l 1230 4515 l 1290 4515 l  cp clip
n 1260.0 1125.0 m 1417.5 1125.0 l
	1417.5 1125.0 1575.0 1125.0 1552.5 1935.0 DrawSplineSection
	1552.5 1935.0 1530.0 2745.0 1395.0 3127.5 DrawSplineSection
	1395.0 3127.5 1260.0 3510.0 1260.0 4005.0 DrawSplineSection
	1260.0 4500.0 l  gs col-1 s gr
 gr

% arrowhead
n 1290 4353 m 1260 4473 l 1230 4353 l 1260 4353 l 1290 4353 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2238 4695 m 2358 4725 l 2238 4755 l 2400 4755 l 2400 4695 l  cp clip
n 1665.0 4860.0 m 1845.0 4860.0 l
	1845.0 4860.0 2025.0 4860.0 2092.5 4792.5 DrawSplineSection
	2092.5 4792.5 2160.0 4725.0 2272.5 4725.0 DrawSplineSection
	2385.0 4725.0 l  gs col-1 s gr
 gr

% arrowhead
n 2238 4695 m 2358 4725 l 2238 4755 l 2238 4725 l 2238 4695 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3678 5595 m 3798 5625 l 3678 5655 l 3840 5655 l 3840 5595 l  cp clip
n 3105.0 5760.0 m 3285.0 5760.0 l
	3285.0 5760.0 3465.0 5760.0 3532.5 5692.5 DrawSplineSection
	3532.5 5692.5 3600.0 5625.0 3712.5 5625.0 DrawSplineSection
	3825.0 5625.0 l  gs col-1 s gr
 gr

% arrowhead
n 3678 5595 m 3798 5625 l 3678 5655 l 3678 5625 l 3678 5595 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
5118 6495 m 5238 6525 l 5118 6555 l 5280 6555 l 5280 6495 l  cp clip
n 4545.0 6660.0 m 4725.0 6660.0 l
	4725.0 6660.0 4905.0 6660.0 4972.5 6592.5 DrawSplineSection
	4972.5 6592.5 5040.0 6525.0 5152.5 6525.0 DrawSplineSection
	5265.0 6525.0 l  gs col-1 s gr
 gr

% arrowhead
n 5118 6495 m 5238 6525 l 5118 6555 l 5118 6525 l 5118 6495 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4048 6182 m 4119 6282 l 4009 6227 l 4132 6333 l 4171 6287 l  cp clip
n 3105.0 6030.0 m 3465.0 6030.0 l
	3465.0 6030.0 3825.0 6030.0 3982.5 6165.0 DrawSplineSection
	4140.0 6300.0 l  gs col-1 s gr
 gr

% arrowhead
n 4048 6182 m 4119 6282 l 4009 6227 l 4028 6204 l 4048 6182 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
3375 2700 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3150 2925 m
gs 1 -1 sc (resname: count) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1845 2925 m
gs 1 -1 sc (resname: sno) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2025 2700 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 4815 m
gs 1 -1 sc (varno:      1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 5085 m
gs 1 -1 sc (varattno:  2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 3510 m
gs 1 -1 sc (Aggreg) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 4005 m
gs 1 -1 sc (target) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 3735 m
gs 1 -1 sc (aggname: count) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 3735 m
gs 1 -1 sc (varno:      1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1890 4005 m
gs 1 -1 sc (varattno:  1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2070 3510 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
810 1530 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
720 405 m
gs 1 -1 sc (AGG) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3915 5445 m
gs 1 -1 sc (Pointer to ) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3915 5835 m
gs 1 -1 sc (SORT node) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3915 5640 m
gs 1 -1 sc (targetlist of) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 900 m
gs 1 -1 sc (qptargetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 630 m
gs 1 -1 sc (aggs) col-1 sh gr
/Times-Roman ff 150.00 scf sf
810 4905 m
gs 1 -1 sc (qptargetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
810 5175 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1170 5535 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2655 6435 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3690 6975 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2250 5805 m
gs 1 -1 sc (qptargetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2250 6075 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3915 6480 m
gs 1 -1 sc (SeqScan) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4095 7290 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 1170 m
gs 1 -1 sc (lefttree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3690 6705 m
gs 1 -1 sc (qptargetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1125 4680 m
gs 1 -1 sc (GRP) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3465 4590 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 5580 m
gs 1 -1 sc (SORT) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 679 2950 a Ft(Figure)f(3.8:)16 b Fp(Plantr)n(ee)d
Ft(for)e(the)i(query)f(of)g(e)o(xample)g(3.2)p eop
%%Page: 65 65
65 64 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(65)198
234 y Fn(Executor)198 329 y Ft(The)13 b Fp(e)o(xecutor)f
Ft(uses)h(the)f(function)g Fr(execAgg\(\))f Ft(to)h(e)o(x)o(ecute)g
Fr(AGG)g Ft(nodes.)k(As)d(described)f(earlier)f(it)198
389 y(uses)k(one)g(main)f(function)f Fr(ExecProcNode)h
Ft(which)g(is)h(called)f(recursi)o(v)o(ely)g(to)g(e)o(x)o(ecute)h
(subtrees.)198 449 y(The)e(follo)o(wing)e(steps)i(are)f(performed)f(by)
h Fr(execAgg\(\))p Ft(:)273 552 y Fo(\017)25 b Ft(The)15
b(list)g(attached)h(to)f(the)g(\002eld)g Fr(aggs)f Ft(of)h(the)g
Fr(AGG)g Ft(node)g(is)h(e)o(xamined)f(and)g(for)f(e)o(v)o(ery)h
Fp(ag-)323 612 y(gr)n(e)n(gate)f(function)f Ft(included)h(the)g
Fp(tr)o(ansition)g(functions)f Ft(are)h(fetched)g(from)f(a)h
Fp(function)f(table)p Ft(.)323 671 y(Calculating)f(the)g(v)o(alue)g(of)
g(an)h Fp(aggr)n(e)n(gate)e(function)h Ft(is)h(done)f(using)g(three)g
(functions:)382 775 y Fn(\226)25 b Ft(The)18 b Fp(\002rst)g(tr)o
(ansition)g(function)f Fr(xfn1)g Ft(is)h(called)g(with)g(the)f(current)
g(v)o(alue)g(of)h(the)f(at-)432 835 y(trib)o(ute)c(the)h
Fp(aggr)n(e)n(gate)f(function)g Ft(is)h(applied)f(to)h(and)g(changes)g
(its)g(internal)f(state)h(using)432 895 y(the)e(attrib)o(ute')m(s)g(v)o
(alue)g(gi)o(v)o(en)g(as)h(an)g(ar)o(gument.)382 976
y Fn(\226)25 b Ft(The)e Fp(second)f(tr)o(ansition)g(function)f
Fr(xfn2)h Ft(is)g(called)g(without)f(an)o(y)h(ar)o(guments)g(and)432
1036 y(changes)13 b(its)g(internal)e(state)i(only)f(according)g(to)g
(internal)g(rules.)382 1118 y Fn(\226)25 b Ft(The)13
b Fp(\002nal)g(function)f Fr(finalfn)g Ft(takes)h(the)g(\002nal)f
(states)h(of)g Fr(xfn1)f Ft(and)h Fr(xfn2)f Ft(as)i(ar)o(gu-)432
1178 y(ments)f(and)f(\002nishes)h(the)f Fp(aggr)n(e)n(gation)p
Ft(.)323 1302 y Fn(Example)g(3.3)25 b Ft(Recall)19 b(the)f(functions)g
(necessary)h(to)f(implement)g(the)g Fp(aggr)n(e)n(gate)g(function)323
1362 y Fr(avg)12 b Ft(b)o(uilding)g(the)h(a)o(v)o(erage)g(o)o(v)o(er)f
(all)h(v)o(alues)g(of)f(an)h(attrib)o(ute)f(in)g(a)h(group)f(\(see)h
(section)g(2.5.5)323 1422 y Fp(Extending)f(Aggr)n(e)n(gates)p
Ft(\):)382 1526 y Fn(\226)25 b Ft(The)10 b(\002rst)f(transition)g
(function)g Fr(xfn1)g Ft(has)h(to)f(be)g(a)h(function)f(that)g(takes)g
(the)h(actual)f(v)o(alue)432 1585 y(of)15 b(the)h(attrib)o(ute)e
Fr(avg)h Ft(is)h(applied)f(to)h(as)g(an)f(ar)o(gument)g(and)g(adds)h
(it)f(to)h(the)f(internally)432 1645 y(stored)d(sum)h(of)f(pre)o(vious)
g(calls.)382 1727 y Fn(\226)25 b Ft(The)15 b(second)h(transition)d
(function)h Fr(xfn2)h Ft(only)f(increases)h(an)g(internal)f(counter)g
(e)o(v)o(ery)432 1787 y(time)e(it)g(is)h(called.)382
1868 y Fn(\226)25 b Ft(The)10 b(\002nal)g(function)f
Fr(finalfn)g Ft(di)o(vides)g(the)h(result)g(of)f Fr(xfn1)g
Ft(by)h(the)g(counter)f(of)g Fr(xfn2)432 1928 y Ft(to)j(calculate)h
(the)f(a)o(v)o(erage.)323 2053 y(Note)h(that)h Fr(xfn2)f
Ft(and)h Fr(finalfn)f Ft(may)h(be)f(absent)i(\(e.g.)20
b(for)13 b(the)g Fp(aggr)n(e)n(gate)g(function)g Fr(sum)323
2113 y Ft(which)f(simply)g(sums)h(up)f(all)g(v)o(alues)h(of)f(the)g(gi)
o(v)o(en)g(attrib)o(ute)g(within)f(a)i(group.)323 2232
y Fr(execAgg\(\))25 b Ft(creates)i(an)g(array)f(containing)g(one)h
(entry)f(for)g(e)o(v)o(ery)h Fp(aggr)n(e)n(gate)f(func-)323
2292 y(tion)16 b Ft(found)h(in)g(the)g(list)g(attached)g(to)g(the)g
(\002eld)g Fr(aggs)p Ft(.)30 b(The)18 b(array)e(will)h(hold)g
(information)323 2352 y(needed)25 b(for)f(the)i(e)o(x)o(ecution)f(of)g
(e)o(v)o(ery)g Fp(aggr)n(e)n(gate)g(function)g Ft(\(including)f(the)h
Fp(tr)o(ansition)323 2412 y(functions)12 b Ft(described)g(abo)o(v)o
(e\).)273 2515 y Fo(\017)25 b Ft(The)15 b(follo)o(wing)f(steps)i(are)f
(e)o(x)o(ecuted)h(in)f(a)g(loop)g(as)g(long)g(as)h(there)f(are)g(still)
g(tuples)g(returned)323 2575 y(by)e(the)h(subplan)g(\(i.e.)20
b(as)15 b(long)e(as)i(there)e(are)h(still)g(tuples)g(left)f(in)h(the)g
(current)f(group\).)19 b(When)323 2635 y(there)12 b(are)h(no)g(tuples)g
(left)f(in)h(the)g(group)f(a)h Fr(NULL)g Ft(pointer)f(is)h(returned)f
(indicating)h(the)g(end)g(of)323 2695 y(the)f(group.)382
2798 y Fn(\226)25 b Ft(A)15 b(ne)o(w)f(tuple)h(from)e(the)i(subplan)g
(\(i.e.)22 b(the)15 b Fp(plan)f Ft(attached)h(to)f(the)h(\002eld)f
Fr(lefttree)p Ft(\))432 2858 y(is)e(fetched)f(by)g(recursi)o(v)o(ely)f
(calling)h Fr(ExecProcNode\(\))f Ft(with)h(the)g(subplan)g(as)h(ar)o
(gu-)432 2918 y(ment.)382 3000 y Fn(\226)25 b Ft(F)o(or)14
b(e)o(v)o(ery)g Fp(aggr)n(e)n(gate)f(function)h Ft(\(contained)f(in)h
(the)g(array)g(created)g(before\))f(apply)h(the)432 3059
y(transition)e(functions)h Fr(xfn1)f Ft(and)h Fr(xfn2)f
Ft(to)h(the)g(v)o(alues)g(of)f(the)h(appropriate)f(attrib)o(utes)432
3119 y(of)g(the)g(current)g(tuple.)273 3223 y Fo(\017)25
b Ft(When)13 b(we)g(get)g(here,)g(all)g(tuples)g(of)g(the)g(current)f
(group)g(ha)o(v)o(e)i(been)f(processed)g(and)g(the)g
Fp(tr)o(an-)323 3283 y(sition)18 b(functions)h Ft(of)g(all)g
Fp(aggr)n(e)n(gate)g(functions)f Ft(ha)o(v)o(e)i(been)f(applied)g(to)g
(the)g(v)o(alues)g(of)g(the)323 3342 y(attrib)o(utes.)c(W)l(e)d(are)g
(no)o(w)g(ready)f(to)h(complete)g(the)g Fp(aggr)n(e)n(gation)f
Ft(by)h(applying)f(the)h Fp(\002nal)g(func-)323 3402
y(tion)f Ft(\()p Fr(finalfn)p Ft(\))g(for)h(e)o(v)o(ery)g
Fp(aggr)n(e)n(gate)g(function)p Ft(.)p eop
%%Page: 66 66
66 65 bop 270 60 a Ft(66)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)345
234 y Fo(\017)25 b Ft(Store)10 b(the)i(tuple)f(containing)g(the)h(ne)o
(w)g(v)o(alues)f(\(the)h(results)f(of)h(the)f Fp(aggr)n(e)n(gate)g
(functions)p Ft(\))g(and)395 294 y(hand)h(it)g(back.)270
405 y(Note)j(that)g(the)g(procedure)f(described)i(abo)o(v)o(e)f(only)g
(returns)g(one)g(tuple)g(\(i.e.)24 b(it)15 b(processes)h(just)f(one)270
465 y(group)f(and)h(when)f(the)h(end)g(of)f(the)h(group)f(is)h
(detected)g(it)f(processes)i(the)f Fp(aggr)n(e)n(gate)f(functions)g
Ft(and)270 524 y(hands)21 b(back)f(one)h(tuple\).)39
b(T)l(o)20 b(retrie)o(v)o(e)g(all)g(tuples)h(\(i.e.)40
b(to)20 b(process)h(all)f(groups\))g(the)g(function)270
584 y Fr(execAgg\(\))15 b Ft(has)i(to)f(be)g(called)h(\(returning)d(a)i
(ne)o(w)h(tuple)e(e)o(v)o(ery)h(time\))g(until)f(it)h(returns)g(a)g
Fr(NULL)270 644 y Ft(pointer)c(indicating)f(that)h(there)g(are)h(no)f
(groups)g(left)g(to)g(process.)270 807 y Fh(3.7.2)59
b(Ho)o(w)15 b(the)g(Ha)o(ving)e(Clause)i(is)g(Implemented)270
908 y Ft(The)k(basic)g(idea)f(of)g(the)g(implementation)f(is)i(to)f
(attach)h(the)f Fp(oper)o(ator)h(tr)n(ee)g Ft(b)o(uilt)f(for)f(the)h
Fp(having)270 968 y(clause)e Ft(to)f(the)g(\002eld)g
Fr(qpqual)f Ft(of)h(node)g Fr(AGG)g Ft(\(which)g(is)h(the)f(top)g(node)
g(of)g(the)g(query)g(tree\).)23 b(No)o(w)270 1028 y(the)17
b(e)o(x)o(ecutor)g(has)h(to)f(e)o(v)o(aluate)g(the)g(ne)o(w)g
Fp(oper)o(ator)h(tr)n(ee)g Ft(attached)f(to)g Fr(qpqual)g
Ft(for)f(e)o(v)o(ery)h(group)270 1087 y(processed.)26
b(If)15 b(the)h(e)o(v)o(aluation)e(returns)h Fr(true)h
Ft(the)f(group)g(is)h(taken)f(into)g(account)h(otherwise)f(it)h(is)270
1147 y(ignored)c(and)g(the)g(ne)o(xt)h(group)e(will)h(be)h(e)o
(xamined.)270 1267 y(In)21 b(order)g(to)g(implement)g(the)g
Fp(having)g(clause)h Ft(a)f(v)o(ariety)g(of)g(changes)h(ha)o(v)o(e)g
(been)f(made)h(to)f(the)270 1326 y(follo)o(wing)11 b(stages:)345
1437 y Fo(\017)25 b Ft(The)15 b Fp(parser)h(stage)f Ft(has)h(been)f
(modi\002ed)g(slightly)g(to)g(b)o(uild)g(up)g(and)h(transform)e(an)h
Fp(oper)o(ator)395 1497 y(tr)n(ee)e Ft(for)e(the)h Fp(having)h(clause)p
Ft(.)345 1612 y Fo(\017)25 b Ft(The)12 b Fp(r)n(e)o(write)i(system)f
Ft(has)g(been)g(adapted)f(to)g(be)h(able)f(to)h(use)f
Fp(vie)o(ws)i Ft(with)e(the)g Fp(having)g(logic)p Ft(.)345
1727 y Fo(\017)25 b Ft(The)12 b Fp(planner/optimizer)g
Ft(no)o(w)g(takes)g(the)g Fp(oper)o(ator)h(tr)n(ee)g
Ft(of)f(the)g Fp(having)g(clause)g Ft(and)h(attaches)395
1787 y(it)f(to)g(the)g Fr(AGG)g Ft(node)h(\(which)e(is)i(the)f(top)h
(node)f(of)g(the)g Fp(queryplan)p Ft(\).)345 1901 y Fo(\017)25
b Ft(The)13 b Fp(e)o(xecutor)g Ft(has)g(been)g(modi\002ed)e(to)i(e)o(v)
o(aluate)f(the)h Fp(oper)o(ator)g(tr)n(ee)g Ft(\(i.e.)k(the)12
b(internal)g(repre-)395 1961 y(sentation)g(of)f(the)i
Fp(having)e(quali\002cation)p Ft(\))g(attached)h(to)g(the)h
Fr(AGG)f Ft(node)g(and)g(the)g(results)g(of)g(the)395
2021 y Fp(aggr)n(e)n(gation)f Ft(are)h(only)g(considered)g(if)g(the)g
(e)o(v)o(aluation)g(returns)g Fr(true)p Ft(.)270 2132
y(In)g(the)g(follo)o(wing)e(sections)j(we)f(will)g(describe)g(the)g
(changes)h(made)f(to)g(e)o(v)o(ery)g(single)g(stage)h(in)f(detail.)270
2285 y Fn(The)g(Parser)i(Stage)270 2386 y Ft(The)g(grammar)f(rules)g
(of)g(the)h Fp(parser)g Ft(de\002ned)g(in)f Fr(gram.y)g
Ft(did)g(not)h(require)e(an)o(y)i(changes)h(\(i.e.)k(the)270
2446 y(rules)14 b(had)g(already)g(been)g(prepared)g(for)f(the)h
Fp(having)g(clause)p Ft(\).)21 b(The)15 b Fp(oper)o(ator)f(tr)n(ee)h
Ft(b)o(uilt)f(up)g(for)f(the)270 2506 y Fp(having)f(clause)h
Ft(is)f(attached)h(to)f(the)g(\002eld)g Fr(havingClause)f
Ft(of)h(the)h Fr(SelectStmt)e Ft(node)h(handed)270 2565
y(back)h(by)f(the)g Fp(parser)p Ft(.)270 2685 y(The)18
b Fp(tr)o(ansformation)g Ft(procedures)f(applied)h(to)f(the)h(tree)f
(handed)h(back)g(by)f(the)h Fp(parser)g Ft(transform)270
2745 y(the)d Fp(oper)o(ator)g(tr)n(ee)g Ft(attached)g(to)g(the)f
(\002eld)h Fr(havingClause)e Ft(using)i(e)o(xactly)g(the)f(same)i
(functions)270 2804 y(used)j(for)f(the)h(transformation)e(of)i(the)g
Fp(oper)o(ator)g(tr)n(ee)h Ft(for)e(the)h Fp(wher)n(e)g(clause)p
Ft(.)36 b(This)20 b(is)f(possible)270 2864 y(because)c(both)e(trees)h
(are)g(b)o(uilt)g(up)f(by)h(the)g(same)h(grammar)d(rules)i(of)g(the)g
Fp(parser)g Ft(and)g(are)g(therefore)270 2924 y(compatible.)h
(Additional)9 b(checks)j(which)e(make)g(sure)h(that)f(the)h
Fp(having)f(clause)h Ft(in)n(v)o(olv)o(es)f(at)h(least)g(one)270
2984 y Fp(aggr)n(e)n(gate)f(function)g Ft(etc.)15 b(are)c(performed)e
(at)h(a)h(later)f(point)g(in)g(time)h(in)f(the)h Fp(planner/optimizer)f
Ft(stage.)270 3103 y(The)24 b(necessary)h(changes)f(ha)o(v)o(e)g(been)g
(applied)g(to)g(the)f(follo)o(wing)g(functions)g(included)g(in)h(the)
270 3163 y(\002le)19 b Fk(:)8 b(:)g(:)p Fr
(/src/backend/parser/analyze.c)o Ft(.)33 b(Note,)21 b(that)d(only)h
(the)g(rele)o(v)o(ant)f(parts)h(of)270 3223 y(the)e(af)o(fected)f(code)
g(are)h(presented)f(instead)h(of)g(the)f(whole)h(functions.)28
b(Ev)o(ery)17 b(added)g(source)f(line)270 3283 y(will)f(be)h(marked)e
(by)h(a)h Fr('+')f Ft(at)h(the)f(be)o(ginning)g(of)g(the)g(line)h(and)f
(e)o(v)o(ery)g(changed)h(source)f(line)g(will)270 3342
y(be)f(marked)f(by)h(a)g Fr('!')19 b Ft(throughout)13
b(the)h(follo)o(wing)e(code)i(listings.)21 b(Whene)o(v)o(er)13
b(a)h(part)g(of)f(the)h(code)270 3402 y(which)e(is)h(not)f(rele)o(v)o
(ant)f(at)i(the)f(moment)g(is)h(skipped,)f(three)g(v)o(ertical)h(dots)f
(are)g(inserted)g(instead.)p eop
%%Page: 67 67
67 66 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(67)273
234 y Fo(\017)25 b Fr(transformInsertStmt\(\))323 294
y Ft(This)14 b(function)e(becomes)i(is)g(in)n(v)o(oked)e(e)o(v)o(ery)i
(time)f(a)g(SQL)h Fr(insert)f Ft(statement)g(in)n(v)o(olving)g(a)323
354 y Fr(select)e Ft(is)i(used)g(like)e(the)i(follo)o(wing)e(e)o
(xample)h(illustrates:)382 467 y Fr(insert)30 b(into)f(t2)382
527 y(select)h(x,)f(y)382 587 y(from)h(t1;)323 700 y
Ft(T)l(wo)10 b(statements)h(ha)o(v)o(e)h(been)f(added)f(to)h(this)g
(function.)j(The)e(\002rst)e(one)h(performs)f(the)g(transfor)o(-)323
760 y(mation)g(of)h(the)h Fp(oper)o(ator)g(tr)n(ee)g
Ft(attached)f(to)h(the)f(\002eld)g Fr(havingClause)f
Ft(using)i(the)f(function)323 819 y Fr(transformWhereClause\(\))h
Ft(as)j(done)f(for)g(the)h Fp(wher)n(e)g(clause)p Ft(.)23
b(It)14 b(is)h(possible)g(to)g(use)323 879 y(the)c(same)h(function)f
(for)g(both)g(clauses,)j(because)e(the)o(y)g(are)f(both)h(b)o(uilt)f
(up)h(by)f(the)h(same)g Fp(gr)o(am-)323 939 y(mar)g(rules)h
Ft(gi)o(v)o(en)f(in)h Fr(gram.y)e Ft(and)i(are)f(therefore)f
(compatible.)323 1017 y(The)h(second)h(statement)f(makes)g(sure,)h
(that)f Fp(aggr)n(e)n(gate)f(functions)h Ft(are)g(in)n(v)o(olv)o(ed)g
(in)g(the)h(query)323 1077 y(whene)o(v)o(er)h(a)h Fp(having)f(clause)h
Ft(is)g(used,)i(otherwise)d(the)h(query)f(could)g(ha)o(v)o(e)i(been)e
(formulated)323 1137 y(using)e(only)g(a)h Fp(wher)n(e)g(clause)p
Ft(.)382 1250 y Fr(static)30 b(Query)f(*)382 1310 y
(transformInsertStmt\(ParseState)e(*pstate,)980 1370
y(InsertStmt)i(*stmt\))382 1430 y({)442 1489 y(/*)h(make)f(a)h(new)g
(query)f(tree)g(*/)442 1549 y(Query)g(*qry)h(=)g(makeNode\(Query\);)
1159 1609 y(.)1159 1669 y(.)1159 1729 y(.)442 1788 y(/*)g(fix)f(where)h
(clause)f(*/)442 1848 y(qry->qual)g(=)h(transformWhereClause\(pstate,)
1428 1908 y(stmt->whereClause\);)323 2027 y(+)89 b(/*)30
b(The)f(havingQual)g(has)h(a)f(similar)g(meaning)h(as)f("qual")g(in)323
2087 y(+)119 b(*)30 b(the)f(where)h(statement.)e(So)i(we)g(can)f
(easily)g(use)h(the)323 2147 y(+)119 b(*)30 b(code)f(from)h(the)f
("where)g(clause")g(with)h(some)f(additional)323 2207
y(+)119 b(*)30 b(traversals)f(done)g(in)h(.../optimizer/plan/planner.c)
323 2267 y(+)119 b(*/)323 2326 y(+)89 b(qry->havingQual)28
b(=)i(transformWhereClause\(pstate,)323 2386 y(+)1045
b(stmt->havingClause\);)1159 2446 y(.)1159 2506 y(.)1159
2565 y(.)323 2625 y(+)89 b(/*)30 b(If)f(there)h(is)f(a)h(havingQual)f
(but)g(there)h(are)f(no)323 2685 y(+)119 b(*)30 b(aggregates,)e(then)i
(there)f(is)h(something)f(wrong)g(with)323 2745 y(+)119
b(*)30 b(the)f(query)h(because)f(having)g(must)g(contain)g(aggregates)
323 2804 y(+)119 b(*)30 b(in)f(its)h(expressions!)f(Otherwise)f(the)i
(query)f(could)323 2864 y(+)119 b(*)30 b(have)f(been)h(formulated)e
(using)i(the)f(where)h(clause.)323 2924 y(+)119 b(*/)323
2984 y(+)89 b(if\(\(qry->hasAggs)28 b(==)i(false\))f(&&)323
3044 y(+)179 b(\(qry->havingQual)28 b(!=)i(NULL\)\))323
3103 y(+)89 b({)323 3163 y(+)149 b(elog\(ERROR,"This)28
b(is)i(not)f(a)h(valid)f(having)g(query!"\);)323 3223
y(+)149 b(return)29 b(\(Query)g(*\)NIL;)323 3283 y(+)89
b(})442 3342 y(return)29 b(\(Query)h(*\))f(qry;)382 3402
y(})p eop
%%Page: 68 68
68 67 bop 270 60 a Ft(68)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)345
234 y Fo(\017)25 b Fr(transformSelectStmt\(\))395 294
y Ft(Exactly)17 b(the)g(same)h(statements)f(added)g(to)g(the)g
(function)f Fr(transformInsertStmt\(\))395 354 y Ft(abo)o(v)o(e)c(ha)o
(v)o(e)h(been)g(added)f(here)g(as)h(well.)454 555 y Fr(static)30
b(Query)f(*)454 614 y(transformSelectStmt\(ParseState)e(*pstate,)1052
674 y(SelectStmt)i(*stmt\))454 734 y({)514 794 y(Query)59
b(*qry)30 b(=)g(makeNode\(Query\);)514 913 y(qry->commandType)e(=)i
(CMD_SELECT;)1231 973 y(.)1231 1033 y(.)1231 1093 y(.)514
1152 y(qry->qual)f(=)h(transformWhereClause\(pstate,)1500
1212 y(stmt->whereClause\);)395 1332 y(+)89 b(/*)30 b(The)f(havingQual)
g(has)h(a)f(similar)g(meaning)h(as)f("qual")g(in)395
1391 y(+)119 b(*)30 b(the)f(where)h(statement.)e(So)i(we)g(can)f
(easily)g(use)h(the)395 1451 y(+)119 b(*)30 b(code)f(from)h(the)f
("where)g(clause")g(with)h(some)f(additional)395 1511
y(+)119 b(*)30 b(traversals)f(done)g(in)h(.../optimizer/plan/planner.c)
395 1571 y(+)119 b(*/)395 1631 y(+)89 b(qry->havingQual)28
b(=)i(transformWhereClause\(pstate,)395 1690 y(+)1045
b(stmt->havingClause\);)1231 1750 y(.)1231 1810 y(.)1231
1870 y(.)395 1929 y(+)89 b(/*)30 b(If)f(there)h(is)f(a)h(havingQual)f
(but)g(there)h(are)f(no)395 1989 y(+)119 b(*)30 b(aggregates,)e(then)i
(there)f(is)h(something)f(wrong)g(with)395 2049 y(+)119
b(*)30 b(the)f(query)h(because)f(having)g(must)g(contain)g(aggregates)
395 2109 y(+)119 b(*)30 b(in)f(its)h(expressions!)f(Otherwise)f(the)i
(query)f(could)395 2169 y(+)119 b(*)30 b(have)f(been)h(formulated)e
(using)i(the)f(where)h(clause.)395 2228 y(+)119 b(*/)395
2288 y(+)89 b(if\(\(qry->hasAggs)28 b(==)i(false\))f(&&)395
2348 y(+)179 b(\(qry->havingQual)28 b(!=)i(NULL\)\))395
2408 y(+)89 b({)395 2467 y(+)149 b(elog\(ERROR,"This)28
b(is)i(not)f(a)h(valid)f(having)g(query!"\);)395 2527
y(+)149 b(return)29 b(\(Query)g(*\)NIL;)395 2587 y(+)89
b(})514 2647 y(return)29 b(\(Query)h(*\))f(qry;)454 2707
y(})270 2951 y Fn(The)12 b(Rewrite)h(System)270 3083
y Ft(This)19 b(section)g(describes)g(the)g(changes)g(to)g(the)f
Fp(r)n(e)o(write)i(system)g Ft(of)e(PostgreSQL)g(that)h(ha)o(v)o(e)g
(been)270 3143 y(necessary)c(to)f(support)g(the)g(use)h(of)f
Fp(vie)o(ws)h Ft(within)f(queries)g(using)g(a)h Fp(having)f(clause)g
Ft(and)g(to)h(support)270 3203 y(the)d(de\002nition)g(of)g
Fp(vie)o(ws)h Ft(by)f(queries)h(using)f(a)h Fp(having)f(clause)p
Ft(.)345 3283 y(As)f(described)h(in)f(section)g(3.4.1)h
Fp(T)-5 b(ec)o(hniques)12 b(T)-5 b(o)11 b(Implement)g(V)l(ie)o(ws)i
Ft(a)e(query)g(re)o(write)f(technique)270 3342 y(is)i(used)h(to)f
(implement)f Fp(vie)o(ws)p Ft(.)17 b(There)12 b(are)g(two)f(cases)j(to)
e(be)g(handled)g(within)f(the)h Fp(r)n(e)o(write)i(system)f
Ft(as)270 3402 y(far)e(as)i(the)g Fp(having)f(clause)g
Ft(is)h(concerned:)p eop
%%Page: 69 69
69 68 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(69)273
234 y Fo(\017)25 b Ft(The)10 b Fp(vie)o(w)h(de\002nition)f
Ft(does)h(not)f(contain)g(a)h Fp(having)f(clause)g Ft(b)o(ut)h(the)f
(queries)g(e)o(v)o(aluated)g(against)323 294 y(this)i(vie)o(w)g(may)g
(contain)g Fp(having)g(clauses)p Ft(.)273 423 y Fo(\017)25
b Ft(The)15 b Fp(vie)o(w)g(de\002nition)f Ft(contains)g(a)h
Fp(having)g(clause)p Ft(.)22 b(In)14 b(this)h(case)h(queries)e(e)o(v)o
(aluated)g(against)323 483 y(this)e(vie)o(w)g(must)g(meet)h(some)f
(restrictions)g(as)h(we)g(will)f(describe)g(later)m(.)198
655 y Fn(No)h(ha)o(ving)f(clause)i(in)f(the)g(view)g(de\002nition:)47
b Ft(First)13 b(we)h(will)f(look)g(at)g(the)g(changes)h(necessary)g(to)
198 715 y(support)e(queries)g(using)h(a)f Fp(having)g(clause)h
Ft(against)f(a)h Fp(vie)o(w)g Ft(de\002ned)f(without)g(a)g
Fp(having)g(clause)p Ft(.)198 835 y(Let)h(the)f(follo)o(wing)f(vie)o(w)
h(de\002nition)g(be)g(gi)o(v)o(en:)258 964 y Fr(create)29
b(view)g(test_view)258 1023 y(as)g(select)h(sno,)f(pno)347
1083 y(from)h(sells)347 1143 y(where)g(sno)f(>)h(2;)198
1264 y Ft(and)12 b(the)h(follo)o(wing)e(query)h(made)g(against)g
Fr(test)p 1083 1264 15 2 v 18 w(view)p Ft(:)258 1393
y Fr(select)29 b(*)258 1453 y(from)g(testview)258 1513
y(where)g(sno)h(<>)f(5;)198 1634 y Ft(The)13 b(query)f(will)g(be)g(re)o
(written)f(to:)258 1763 y Fr(select)29 b(sno,)g(pno)258
1823 y(from)g(sells)258 1883 y(where)g(sno)h(>)f(2)h(and)437
1943 y(sno)g(<>)f(5;)198 2064 y Ft(The)13 b(query)g(gi)o(v)o(en)g(in)f
(the)h(de\002nition)f(of)h(the)g Fp(vie)o(w)g Fr(test)p
1221 2064 V 18 w(view)f Ft(is)h(the)g Fp(bac)o(kbone)g
Ft(of)g(the)f(re)o(written)198 2124 y(query)m(.)k(The)d
Fp(tar)n(getlist)f Ft(is)h(taken)f(from)g(the)h(user')m(s)g(query)f
(and)g(also)h(the)g Fp(wher)n(e)h(quali\002cation)24
b Ft(of)12 b(the)198 2184 y(user')m(s)e(query)f(is)h(added)f(to)h(the)f
Fp(wher)n(e)i(quali\002cation)d Ft(of)h(the)h(ne)o(w)f(query)g(by)h
(using)f(an)h Fr(AND)f Ft(operation.)198 2303 y(No)o(w)j(consider)g
(the)h(follo)o(wing)e(query:)258 2432 y Fr(select)29
b(sno,)g(count\(pno\))258 2492 y(from)g(testview)258
2552 y(where)g(sno)h(<>)f(5)258 2611 y(group)g(by)h(sno)258
2671 y(having)f(count\(pno\))g(>)h(1;)198 2793 y Ft(From)12
b(no)o(w)g(on)h(it)g(is)g(no)f(longer)h(suf)o(\002cient)f(to)g(add)h
(just)g(the)g Fp(wher)n(e)h(clause)f Ft(and)g(the)f Fp(tar)n(getlist)h
Ft(of)f(the)198 2853 y(user')m(s)i(query)f(to)h(the)g(ne)o(w)f(query)m
(.)19 b(The)c Fp(gr)n(oup)e(clause)h Ft(and)g(the)g Fp(having)f
(quali\002cation)g Ft(also)h(ha)o(v)o(e)g(to)198 2912
y(be)e(added)h(to)f(the)g(re)o(written)f(query:)258 3041
y Fr(select)29 b(sno,)g(count\(pno\))258 3101 y(from)g(sells)258
3161 y(where)g(sno)h(>)f(2)h(and)437 3221 y(sno)g(<>)f(5)258
3280 y(group)g(by)h(sno)258 3340 y(having)f(count\(pno\))g(>)h(1;)p
eop
%%Page: 70 70
70 69 bop 270 60 a Ft(70)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(Se)o(v)o(eral)i(changes)g(that)h(ha)o(v)o(e)f(already)g(been)g
(applied)g(to)g(the)h Fp(tar)n(getlist)f Ft(and)g(the)g
Fp(wher)n(e)h(clause)g Ft(also)270 294 y(ha)o(v)o(e)c(to)g(be)g
(applied)f(to)h(the)g Fp(having)f(clause)p Ft(.)16 b(Here)10
b(is)h(a)g(collection)g(of)f(all)h Fp(additional)f Ft(steps)h(that)g
(ha)o(v)o(e)270 354 y(to)g(be)g(performed)f(in)h(order)g(to)g(re)o
(write)f(a)h(query)g(using)g(a)h Fp(having)e(clause)i
Ft(against)f(a)h(simple)f Fp(vie)o(w)h Ft(\(i.e.)270
413 y(a)h Fp(vie)o(w)g Ft(whose)f(de\002nition)g(does)h(not)f(use)g(an)
o(y)h Fp(gr)n(oup)f Ft(and)h Fp(having)f(clauses)p Ft(\):)345
523 y Fo(\017)25 b Ft(Re)o(write)11 b(the)i(subselects)g(contained)f
(in)h(the)f Fp(having)g(clause)h Ft(if)f(an)o(y)g(are)g(present.)345
635 y Fo(\017)25 b Ft(Adapt)12 b(the)g Fr(varno)g Ft(and)g
Fr(varattno)f Ft(\002elds)i(of)e(all)i Fr(VAR)f Ft(nodes)g(contained)g
(in)g(the)g Fp(oper)o(ator)395 695 y(tr)n(ee)i Ft(representing)g(the)f
Fp(having)h(clause)h Ft(in)e(the)h(same)h(way)e(as)i(it)f(has)g(been)g
(done)g(for)f(the)h(tree)395 755 y(representing)e(the)g
Fp(wher)n(e)i(clause)p Ft(.)j(The)d Fr(varno)e Ft(\002elds)h(are)f
(changed)h(to)g(use)g(the)g Fp(base)g(tables)395 814
y Ft(gi)o(v)o(en)g(in)g(the)h Fp(vie)o(w)g(de\002nition)e
Ft(\(which)h(ha)o(v)o(e)h(been)g(inserted)f(into)g(the)g
Fp(r)o(ange)h(table)f(entry)h(list)395 874 y Ft(in)h(the)h(meantime\))f
(instead)i(of)e(the)h Fp(virtual)g(tables)p Ft(.)27 b(The)17
b(positions)f(of)f(the)h(attrib)o(utes)g(used)395 934
y(in)d(the)g Fp(vie)o(w)h Ft(may)g(dif)o(fer)e(from)g(the)h(positions)h
(of)f(the)g(corresponding)g(attrib)o(utes)g(in)g(the)h
Fp(base)395 994 y(tables)p Ft(.)h(That')m(s)e(why)f(the)h
Fr(varattno)e Ft(\002elds)i(also)f(ha)o(v)o(e)h(to)f(be)h(adapted.)345
1106 y Fo(\017)25 b Ft(Adapt)i(the)h Fr(varno)f Ft(and)h
Fr(varattno)f Ft(\002elds)h(of)f(all)h Fr(VAR)f Ft(nodes)h(contained)g
(in)f(the)395 1166 y Fr(groupClause)11 b Ft(of)h(the)g(user')m(s)h
(query)f(in)g(the)g(way)g(and)g(for)g(the)g(reasons)h(described)f(abo)o
(v)o(e.)345 1278 y Fo(\017)25 b Ft(Attach)19 b(the)g(tree)g
(representing)g(the)h Fp(having)f(quali\002cation)f Ft(\(which)h(is)h
(currently)e(attached)395 1338 y(to)d(the)i(\002eld)e
Fr(havingClause)g Ft(of)h(the)g Fr(Query)f Ft(node)i(for)e(the)h(user')
m(s)g(query\))f(to)h(the)g(\002eld)395 1398 y Fr(havingClause)11
b Ft(of)h(the)g Fr(Query)g Ft(node)g(for)g(the)g(ne)o(w)g(\(re)o
(written\))e(query)m(.)345 1510 y Fo(\017)25 b Ft(Attach)j(the)h(list)g
(representing)f(the)h Fp(gr)n(oup)g(clause)g Ft(\(currently)f(attached)
h(to)g(the)f(\002eld)395 1570 y Fr(groupClause)10 b Ft(of)h(the)g
Fr(Query)g Ft(node)g(for)f(the)h(user')m(s)h(query\))e(to)i(the)f
(\002eld)g Fp(gr)n(oup)g(clause)h Ft(of)395 1630 y(the)g(node)g(for)g
(the)g(ne)o(w)g(\(re)o(written\))e(query)m(.)270 1780
y Fn(The)15 b(view)h(de\002nition)d(contains)i(a)g(ha)o(ving)f(clause:)
50 b Ft(No)o(w)15 b(we)g(will)g(look)g(at)g(the)g(problems)g(that)270
1840 y(can)e(arise)f(using)g Fp(vie)o(ws)i Ft(that)e(are)g(de\002ned)g
(using)h(a)f(query)g(in)n(v)o(olving)g(a)g Fp(having)g(clause)p
Ft(.)270 1959 y(Let)h(the)f(follo)o(wing)f Fp(vie)o(w)i(de\002nition)f
Ft(be)g(gi)o(v)o(en:)330 2072 y Fr(create)29 b(view)g(test_view)330
2132 y(as)g(select)h(sno,)f(count\(pno\))g(as)h(number)419
2191 y(from)g(sells)419 2251 y(where)g(sno)f(>)h(2)419
2311 y(group)g(by)f(sno)419 2371 y(having)h(count\(pno\))e(>)i(1;)270
2480 y Ft(Simple)12 b(queries)g(against)g(this)h Fp(vie)o(w)g
Ft(will)f(not)g(cause)h(an)o(y)f(troubles:)330 2592 y
Fr(select)29 b(*)330 2652 y(from)g(test_view)330 2712
y(where)g(sno)h(<>)f(5;)270 2821 y Ft(This)17 b(query)g(can)g(easily)g
(be)g(re)o(written)f(by)g(adding)h(the)g Fp(wher)n(e)g(quali\002cation)
f Ft(of)h(the)f(user')m(s)i(query)270 2881 y(\()p Fr(sno)29
b Fk(<>)h Fr(5)p Ft(\))11 b(to)i(the)f Fp(wher)n(e)h(quali\002cation)f
Ft(of)g(the)g Fp(vie)o(w)h(de\002nition')n(s)24 b Ft(query)m(.)270
3000 y(The)f(ne)o(xt)g(query)f(is)h(also)g(simple)g(b)o(ut)f(it)g(will)
h(cause)g(troubles)f(when)h(it)f(is)h(e)o(v)o(aluated)f(against)270
3060 y(the)12 b(abo)o(v)o(e)h(gi)o(v)o(en)f Fp(vie)o(w)h(de\002nition)p
Ft(:)330 3173 y Fr(select)29 b(*)330 3232 y(from)g(test_view)330
3292 y(where)g(number)g(>)h(1;)g(/*)f(count\(pno\))g(in)h(the)f(view)h
(def.)898 3352 y(*)f(is)h(called)59 b(number)29 b(here)h(*/)p
eop
%%Page: 71 71
71 70 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(71)198
234 y(The)13 b(currently)e(implemented)h(techniques)g(for)g(query)g(re)
o(writing)e(will)i(re)o(write)g(the)g(query)g(to:)258
368 y Fr(select)29 b(*)258 428 y(from)g(sells)258 487
y(where)g(sno)h(>)f(2)h(and)437 547 y(count\(pno\))f(>)h(1)258
607 y(group)f(by)h(sno)258 667 y(having)f(count\(pno\))g(>)h(1;)198
792 y Ft(which)12 b(is)h(an)f(in)n(v)o(alid)g(query)g(because)h(an)f
Fp(aggr)n(e)n(gate)g(function)g Ft(appears)g(in)h(the)f
Fp(wher)n(e)h(clause)p Ft(.)198 912 y(Also)g(the)f(ne)o(xt)g(query)g
(will)g(cause)h(troubles:)258 1045 y Fr(select)29 b(pno,)g
(count\(sno\))258 1105 y(from)g(test_view)258 1165 y(group)g(by)h(pno;)
198 1290 y Ft(As)16 b(you)f(can)h(see)g(this)g(query)f(does)h(neither)f
(in)n(v)o(olv)o(e)g(a)h Fp(wher)n(e)g(clause)g Ft(nor)f(a)h
Fp(having)f(clause)h Ft(b)o(ut)f(it)198 1350 y(contains)i(a)g
Fp(gr)n(oup)g(clause)g Ft(which)g(groups)g(by)g(the)g(attrib)o(ute)f
Fr(pno)p Ft(.)29 b(The)18 b(query)e(in)h(the)g(de\002nition)198
1410 y(of)d(the)g Fp(vie)o(w)h Ft(also)g(contains)f(a)h
Fp(gr)n(oup)f(clause)h Ft(that)f(groups)g(by)g(the)h(attrib)o(ute)e
Fr(sno)p Ft(.)22 b(The)15 b(two)e Fp(gr)n(oup)198 1469
y(clauses)19 b Ft(are)f(in)h(con\003ict)e(with)i(each)f(other)g(and)g
(therefore)g(the)g(query)g(cannot)g(be)h(re)o(written)e(to)h(a)198
1529 y(form)11 b(that)h(would)g(make)g(sense.)198 1649
y Fn(Note:)38 b Ft(There)24 b(is)g(no)g(solution)g(to)g(the)g(abo)o(v)o
(e)g(mentioned)g(problems)f(at)h(the)g(moment)f(and)h(it)198
1709 y(does)12 b(not)f(make)g(sense)h(to)f(put)g(much)h(ef)o(fort)d
(into)i(that)h(because)g(the)f(implementation)f(of)h(the)h(support)198
1768 y(for)g(queries)g(like:)258 1902 y Fr(select)29
b(pno_count,)g(count\(sno\))258 1962 y(from)g(\()h(select)f(sno,)h
(count\(pno\))e(as)i(pno_count)467 2022 y(from)f(sells)467
2081 y(where)g(sno)h(>)g(2)467 2141 y(group)f(by)h(sno)467
2201 y(having)f(count\(pno\))g(>)h(1\))258 2261 y(group)f(by)h
(pno_count;)198 2386 y Ft(\(which)12 b(is)g(part)g(of)g(the)h(SQL92)f
(standard\))g(will)g(automatically)f(also)i(solv)o(e)g(these)g
(problems.)198 2506 y(In)26 b(the)h(ne)o(xt)g(part)f(of)h(the)g
(current)f(section)h(we)g(will)f(present)h(the)g(changes)g(applied)f
(to)h(the)198 2565 y(source)15 b(code)f(in)h(order)f(to)g(realize)h
(the)f(abo)o(v)o(e)h(described)g(items.)22 b(Note)15
b(that)f(it)h(is)g(not)f(necessary)h(to)198 2625 y(understand)e(the)h
(meaning)g(of)f(e)o(v)o(ery)h(single)g(source)f(line)h(here)g(and)f
(therefore)g(we)h(will)g(not)f(discuss)198 2685 y(detailed)j(questions)
g(like)g(\224Why)g(has)g(the)g(v)o(ariable)g Fr(varno)f
Ft(to)h(be)g(increased)h(by)f(3?\224.)27 b(Questions)198
2745 y(like)13 b(that)h(belong)f(to)h(a)g(chapter)f(dealing)g(with)h
(the)g(implementation)e(of)h Fp(vie)o(ws)i Ft(in)f(PostgreSQL)f(and)198
2804 y(to)k(be)g(able)g(to)g(answer)g(them)g(it)g(would)f(be)h
(necessary)h(to)f(kno)o(w)f(all)h(the)g(functions)g(and)g(not)f(only)
198 2864 y(those)g(described)g(here.)25 b(The)17 b(fact)e(important)f
(for)h(us)h(is)g(to)g(make)f(sure,)i(that)f(whate)o(v)o(er)f(is)h
(applied)198 2924 y(to)d(the)g Fp(tar)n(getlist)g Ft(and)g(the)g(data)h
(structures)f(representing)f(the)h Fp(wher)n(e)i(clause)e
Ft(is)h(also)f(applied)g(to)g(the)198 2984 y(data)f(structures)h(for)e
(the)h Fp(having)g(clause)p Ft(.)17 b(There)12 b(are)h(three)f(\002les)
g(af)o(fected:)273 3103 y Fk(:)c(:)g(:)p Fr
(/src/backend/rewrite/rewriteHa)o(ndler.c)273 3163 y
Fk(:)g(:)g(:)p Fr(/src/backend/rewrite/rewriteMa)o(nip.c)273
3223 y Fk(:)g(:)g(:)p Fr(/src/backend/commands/view.c)198
3342 y Ft(Here)29 b(is)h(a)g(description)f(of)g(the)g(changes)h(made)g
(to)f(the)g(functions)g(contained)h(in)f(the)g(\002le)198
3402 y Fk(:)8 b(:)g(:)p Fr(/src/backend/rewrite/rewriteHandl)o(er.c)p
Ft(:)p eop
%%Page: 72 72
72 71 bop 270 60 a Ft(72)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)345
234 y Fo(\017)25 b Fr(ApplyRetrieveRule\(\))395 294 y
Ft(This)g(function)g(becomes)g(in)n(v)o(oked)f(whene)o(v)o(er)h(a)g
Fr(select)g Ft(statement)g(against)g(a)g Fp(vie)o(w)395
354 y Ft(is)f(recognized)g(and)g(applies)g(the)g Fp(r)n(e)o(write)h
(rule)g Ft(stored)f(in)f(the)h Fp(system)h(catalogs)p
Ft(.)51 b(The)395 413 y(additional)23 b(source)h(lines)g(gi)o(v)o(en)f
(in)h(the)g(listing)f(belo)o(w)h(make)f(sure)h(that)g(the)g(functions)
395 473 y Fr(OffsetVarNodes\(\))12 b Ft(and)j Fr(ChangeVarNodes\(\))d
Ft(that)i(are)h(in)n(v)o(oked)e(for)h(the)g Fp(wher)n(e)395
533 y(clause)g Ft(and)h(the)f Fp(tar)n(getlist)g Ft(of)g(the)g(query)g
(gi)o(v)o(en)g(in)h(the)f Fp(vie)o(w)h(de\002nition)f
Ft(are)g(also)h(called)f(for)395 593 y(the)i Fp(having)h(clause)g
Ft(and)g(the)g Fp(gr)n(oup)g(clause)g Ft(of)f(the)h(query)f(in)h(the)g
Fp(vie)o(w)g(de\002nition)p Ft(.)29 b(These)395 653 y(functions)11
b(adapt)i(the)f Fr(varno)g Ft(and)g Fr(varattno)g Ft(\002elds)g(of)g
(the)h Fr(VAR)f Ft(nodes)g(in)n(v)o(olv)o(ed.)395 730
y(The)g(additional)g(source)g(lines)g(at)g(the)g(end)g(of)g
Fr(ApplyRetrieveRule\(\))e Ft(attach)i(the)g(data)395
790 y(structures)k(representing)g(the)h Fp(having)f(clause)i
Ft(and)e(the)h Fp(gr)n(oup)g(clause)g Ft(of)f(the)h(query)f(in)h(the)
395 850 y Fp(vie)o(w)h(de\002nition)g Ft(to)g(the)g(re)o(written)e
Fp(parsetr)n(ee)p Ft(.)34 b(As)19 b(mentioned)e(earlier)n(,)j(a)e
Fp(vie)o(w)h(de\002nition)395 910 y Ft(in)n(v)o(olving)8
b(a)i Fp(gr)n(oup)g(clause)g Ft(will)g(cause)g(troubles)f(whene)o(v)o
(er)h(a)g(query)f(using)h(a)g(dif)o(ferent)e Fp(gr)n(oup)395
969 y(clause)i Ft(against)f(this)h Fp(vie)o(w)h Ft(is)f(e)o(x)o
(ecuted.)16 b(There)10 b(is)g(no)f(mechanism)h(pre)o(v)o(enting)f
(these)i(troubles)395 1029 y(included)h(at)g(the)g(moment.)395
1107 y(Note)30 b(that)g(the)g(functions)g Fr(OffsetVarNodes\(\))e
Ft(,)36 b Fr(ChangeVarNodes\(\))28 b Ft(and)395 1167
y Fr(AddHavingQual\(\))14 b Ft(appearing)i(in)g Fr
(ApplyRetrieveRule\(\))e Ft(are)i(described)h(at)f(a)395
1227 y(later)c(point)f(in)i(time.)454 1337 y Fr(static)30
b(void)454 1397 y(ApplyRetrieveRule\(Query)e(*parsetree,)g(RewriteRule)
h(*rule,)992 1456 y(int)h(rt_index,)f(int)g(relation_level,)992
1516 y(Relation)g(relation,)g(int)h(*modified\))454 1576
y({)514 1636 y(Query)59 b(*rule_action)29 b(=)h(NULL;)514
1696 y(Node)89 b(*rule_qual;)514 1755 y(List)g(*rtable,)1231
1815 y(.)1231 1875 y(.)1231 1935 y(.)514 1994 y(OffsetVarNodes\(\(Node)
28 b(*\))h(rule_action->targetList,)962 2054 y(rt_length\);)514
2114 y(OffsetVarNodes\(rule_qual,)e(rt_length\);)395
2233 y(+)89 b(OffsetVarNodes\(\(Node)28 b(*\))h
(rule_action->groupClause,)395 2293 y(+)537 b(rt_length\);)395
2353 y(+)89 b(OffsetVarNodes\(\(Node)28 b(*\))h
(rule_action->havingQual,)395 2413 y(+)537 b(rt_length\);)1231
2473 y(.)1231 2532 y(.)1231 2592 y(.)514 2652 y
(ChangeVarNodes\(rule_qual,)962 2712 y(PRS2_CURRENT_VARNO)28
b(+)i(rt_length,)962 2771 y(rt_index,)f(0\);)395 2891
y(+)89 b(ChangeVarNodes\(\(Node)28 b(*\))h(rule_action->groupClause,)
395 2951 y(+)537 b(PRS2_CURRENT_VARNO)28 b(+)i(rt_length,)395
3011 y(+)537 b(rt_index,)29 b(0\);)395 3070 y(+)89 b
(ChangeVarNodes\(\(Node)28 b(*\))h(rule_action->havingQual,)395
3130 y(+)537 b(PRS2_CURRENT_VARNO)28 b(+)i(rt_length,)395
3190 y(+)537 b(rt_index,)29 b(0\);)1231 3250 y(.)1231
3309 y(.)1231 3369 y(.)p eop
%%Page: 73 73
73 72 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(73)442
234 y Fr(if)30 b(\(*modified)f(&&)g(!badsql\))442 294
y({)502 354 y(AddQual\(parsetree,)f(rule_action->qual\);)323
413 y(+)149 b(/*)30 b(This)f(will)g(only)h(work)f(if)h(the)f(query)h
(made)f(to)h(the)323 473 y(+)179 b(*)30 b(view)f(defined)g(by)h(the)f
(following)g(groupClause)323 533 y(+)179 b(*)30 b(groups)f(by)g(the)h
(same)f(attributes)g(or)h(does)f(not)h(use)323 593 y(+)179
b(*)30 b(groups)f(at)g(all!)323 653 y(+)179 b(*/)323
712 y(+)g(if)29 b(\(parsetree->groupClause)f(==)h(NULL\))323
772 y(+)268 b(parsetree->groupClause)28 b(=)323 832 y(+)597
b(rule_action->groupClause;)323 892 y(+)179 b
(AddHavingQual\(parsetree,)323 951 y(+)597 b
(rule_action->havingQual\);)323 1011 y(+)179 b(parsetree->hasAggs)28
b(=)323 1071 y(+)268 b(\(rule_action->hasAggs)28 b(||)i
(parsetree->hasAggs\);)323 1131 y(+)179 b(parsetree->hasSubLinks)27
b(=)323 1191 y(+)268 b(\(rule_action->hasSubLinks)27
b(||)323 1250 y(+)298 b(parsetree->hasSubLinks\);)442
1310 y(})382 1370 y(})273 1529 y Fo(\017)25 b Fr
(QueryRewriteSubLink\(\))323 1588 y Ft(This)17 b(function)e(is)i
(called)g(by)g Fr(QueryRewrite\(\))e Ft(to)h(process)h(possibly)g
(contained)f(sub-)323 1648 y(queries)d(\002rst.)k(It)c(searches)h(for)e
(nested)i(queries)f(by)g(recursi)o(v)o(ely)f(tracing)h(through)f(the)h
Fp(parse-)323 1708 y(tr)n(ee)h Ft(gi)o(v)o(en)g(as)g(ar)o(gument.)20
b(The)15 b(additional)e(statement)h(makes)g(sure)g(that)f(the)h
Fp(having)g(clause)323 1768 y Ft(is)e(also)h(e)o(xamined.)382
1911 y Fr(static)30 b(void)382 1970 y(QueryRewriteSubLink\(Node)e
(*node\))382 2030 y({)442 2090 y(if)i(\(node)f(==)h(NULL\))532
2150 y(return;)442 2209 y(switch)f(\(nodeTag\(node\)\))442
2269 y({)502 2329 y(case)g(T_SubLink:)502 2389 y({)1159
2449 y(.)1159 2508 y(.)1159 2568 y(.)592 2628 y
(QueryRewriteSubLink\(\(Node)e(*\))i(query->qual\);)323
2688 y(+)239 b(QueryRewriteSubLink\(\(Node)27 b(*\))323
2747 y(+)836 b(query->havingQual\);)1159 2807 y(.)1159
2867 y(.)1159 2927 y(.)502 2987 y(})1159 3046 y(.)1159
3106 y(.)1159 3166 y(.)442 3226 y(})442 3285 y(return;)382
3345 y(})p eop
%%Page: 74 74
74 73 bop 270 60 a Ft(74)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)345
234 y Fo(\017)25 b Fr(QueryRewrite\(\))395 294 y Ft(This)c(function)g
(takes)g(the)g Fp(parsetr)n(ee)h Ft(of)f(a)h(query)f(and)g(re)o(writes)
f(it)i(using)f(PostgreSQL)-5 b(')m(s)395 354 y Fp(r)n(e)o(write)27
b(system)p Ft(.)58 b(Before)26 b(the)g(query)g(itself)g(can)h(be)f(re)o
(written,)j(subqueries)d(that)g(are)395 413 y(possibly)33
b(part)f(of)g(the)h(query)f(ha)o(v)o(e)i(to)e(be)h(processed.)78
b(Therefore)32 b(the)h(function)395 473 y Fr(QueryRewriteSubLink\(\))17
b Ft(is)k(called)f(for)g(the)g Fp(wher)n(e)h(clause)g
Ft(and)f(for)f(the)h Fp(having)395 533 y(clause)p Ft(.)454
648 y Fr(List)30 b(*)454 708 y(QueryRewrite\(Query)e(*parsetree\))454
768 y({)514 828 y(QueryRewriteSubLink\(parsetree->q)o(ual\);)395
887 y(+)89 b(QueryRewriteSubLink\(parsetree->h)o(avingQual)o(\);)514
947 y(return)29 b(QueryRewriteOne\(parsetree\);)454 1007
y(})270 1122 y Ft(Here)c(we)h(present)f(the)g(changes)h(applied)f(to)g
(the)h(functions)e(that)i(are)f(contained)g(in)g(the)g(\002le)270
1182 y Fk(:)8 b(:)g(:)p Fr(/src/backend/rewrite/rewriteManip)o(.c)p
Ft(:)345 1278 y Fo(\017)25 b Fr(OffsetVarNodes\(\))395
1338 y Ft(Recursi)o(v)o(ely)15 b(steps)h(through)f(the)g
Fp(parsetr)n(ee)i Ft(gi)o(v)o(en)e(as)h(the)g(\002rst)f(ar)o(gument)g
(and)g(increments)395 1398 y(the)h Fr(varno)f Ft(and)h
Fr(varnoold)f Ft(\002elds)h(of)g(e)o(v)o(ery)g Fr(VAR)f
Ft(node)h(found)g(by)g(the)g Fp(of)o(fset)g Ft(gi)o(v)o(en)g(as)395
1457 y(the)f(second)h(ar)o(gument.)24 b(The)16 b(additional)f
(statements)g(are)h(necessary)g(to)f(be)g(able)h(to)f(handle)395
1517 y Fr(GroupClause)e Ft(nodes)h(and)g Fr(Sublink)g
Ft(nodes)h(that)f(may)g(appear)g(in)g(the)g Fp(parsetr)n(ee)h
Ft(from)395 1577 y(no)o(w)d(on.)454 1692 y Fr(void)454
1752 y(OffsetVarNodes\(Node)28 b(*node,)h(int)h(offset\))454
1812 y({)544 1871 y(if)g(\(node)f(==)h(NULL\))634 1931
y(return;)544 1991 y(switch)f(\(nodeTag\(node\)\))544
2051 y({)1231 2111 y(.)1231 2170 y(.)1231 2230 y(.)395
2290 y(+)209 b(/*)29 b(This)h(has)f(to)h(be)g(done)f(to)h(make)f
(queries)g(using)395 2350 y(+)239 b(*)29 b(groupclauses)g(work)g(on)h
(views)395 2409 y(+)239 b(*/)395 2469 y(+)g(case)29 b(T_GroupClause:)
395 2529 y(+)239 b({)395 2589 y(+)298 b(GroupClause)29
b(*group)g(=)h(\(GroupClause)e(*\))i(node;)395 2649 y(+)395
2708 y(+)298 b(OffsetVarNodes\(\(Node)28 b(*\)\(group->entry\),)395
2768 y(+)747 b(offset\);)395 2828 y(+)239 b(})395 2888
y(+)g(break;)1231 2947 y(.)1231 3007 y(.)1231 3067 y(.)395
3127 y(+)g(case)29 b(T_SubLink:)395 3187 y(+)239 b({)395
3246 y(+)298 b(SubLink)29 b(*sublink)g(=)h(\(SubLink)f(*\))h(node;)395
3306 y(+)298 b(List)30 b(*tmp_oper,)f(*tmp_lefthand;)395
3366 y(+)p eop
%%Page: 75 75
75 74 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(75)323
234 y Fr(+)298 b(/*)30 b(We)g(also)f(have)h(to)f(adapt)g(the)h
(variables)f(used)323 294 y(+)328 b(*)30 b(in)g(sublink->lefthand)e
(and)h(sublink->oper)323 354 y(+)328 b(*/)323 413 y(+)298
b(OffsetVarNodes\(\(Node)28 b(*\)\(sublink->lefthand\),)323
473 y(+)747 b(offset\);)323 533 y(+)323 593 y(+)298 b(/*)30
b(Make)f(sure)h(the)f(first)h(argument)f(of)323 653 y(+)328
b(*)30 b(sublink->oper)e(points)i(to)f(the)h(same)f(var)h(as)323
712 y(+)328 b(*)30 b(sublink->lefthand)e(does)h(otherwise)g(we)h(will)
323 772 y(+)328 b(*)30 b(run)g(into)f(troubles)g(using)g(aggregates)g
(\(aggno)323 832 y(+)328 b(*)30 b(will)f(not)h(be)g(set)f(correctly\))
323 892 y(+)328 b(*/)323 951 y(+)298 b(tmp_lefthand)29
b(=)h(sublink->lefthand;)323 1011 y(+)298 b(foreach\(tmp_oper,)28
b(sublink->oper\))323 1071 y(+)298 b({)323 1131 y(+)358
b(lfirst\(\(\(Expr)29 b(*\)lfirst\(tmp_oper\)\)->args\))d(=)323
1191 y(+)1016 b(lfirst\(tmp_lefthand\);)323 1250 y(+)358
b(tmp_lefthand)29 b(=)g(lnext\(tmp_lefthand\);)323 1310
y(+)298 b(})323 1370 y(+)239 b(})323 1430 y(+)g(break;)1159
1489 y(.)1159 1549 y(.)1159 1609 y(.)472 1669 y(})382
1729 y(})273 1838 y Fo(\017)25 b Fr(ChangeVarNodes\(\))323
1898 y Ft(This)d(function)f(is)h(similar)f(to)h(the)g(abo)o(v)o(e)g
(described)g(function)f Fr(OffsetVarNodes\(\))323 1958
y Ft(b)o(ut)e(instead)h(of)f(incrementing)g(the)h(\002elds)g
Fr(varno)f Ft(and)h Fr(varnoold)f Ft(of)g Fp(all)g Fr(VAR)h
Ft(nodes)323 2017 y(found,)j(it)e(processes)h(only)f(those)g
Fr(VAR)g Ft(nodes)h(whose)f Fr(varno)g Ft(v)o(alue)g(matches)g(the)g
(pa-)323 2077 y(rameter)13 b Fr(old)p 582 2077 15 2 v
18 w(varno)h Ft(gi)o(v)o(en)g(as)h(ar)o(gument)f(and)g(whose)h
Fr(varlevelsup)f Ft(v)o(alue)g(matches)323 2137 y(the)i(parameter)g
Fr(sublevels)p 889 2137 V 17 w(up)p Ft(.)29 b(Whene)o(v)o(er)17
b(such)g(a)g(node)g(is)g(found,)h(the)f Fr(varno)f Ft(and)323
2197 y Fr(varnoold)10 b Ft(\002elds)h(are)g(set)g(to)g(the)g(v)o(alue)g
(gi)o(v)o(en)g(in)g(the)g(parameter)f Fr(new)p 1615 2197
V 18 w(varno)p Ft(.)15 b(The)d(addi-)323 2257 y(tional)g(statements)i
(are)f(necessary)h(to)f(be)h(able)f(to)g(handle)g Fr(GroupClause)f
Ft(and)i Fr(Sublink)323 2316 y Ft(nodes.)382 2419 y Fr(void)382
2479 y(ChangeVarNodes\(Node)28 b(*node,)h(int)h(old_varno,)831
2539 y(int)f(new_varno,)g(int)g(sublevels_up\))382 2599
y({)442 2658 y(if)h(\(node)f(==)h(NULL\))532 2718 y(return;)442
2778 y(switch)f(\(nodeTag\(node\)\))442 2838 y({)1159
2897 y(.)1159 2957 y(.)1159 3017 y(.)323 3077 y(+)149
b(/*)30 b(This)f(has)h(to)f(be)h(done)f(to)h(make)f(queries)g(using)323
3137 y(+)179 b(*)30 b(groupclauses)e(work)i(on)f(views)g(*/)323
3196 y(+)149 b(case)29 b(T_GroupClause:)323 3256 y(+)149
b({)323 3316 y(+)209 b(GroupClause)58 b(*group)29 b(=)h(\(GroupClause)f
(*\))g(node;)323 3376 y(+)p eop
%%Page: 76 76
76 75 bop 270 60 a Ft(76)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)395
234 y Fr(+)209 b(ChangeVarNodes\(\(Node)27 b(*\)\(group->entry\),)395
294 y(+)657 b(old_varno,)29 b(new_varno,)395 354 y(+)657
b(sublevels_up\);)395 413 y(+)149 b(})395 473 y(+)g(break;)1231
533 y(.)1231 593 y(.)1231 653 y(.)574 712 y(case)29 b(T_Var:)574
772 y({)1231 832 y(.)1231 892 y(.)1231 951 y(.)634 1011
y(/*)g(This)h(is)f(a)h(hack:)g(Whenever)e(an)i(attribute)664
1071 y(*)f(from)h(the)f("outside")g(query)g(is)h(used)g(within)664
1131 y(*)f(a)h(nested)f(subquery,)g(the)h(varlevelsup)e(will)664
1191 y(*)h(be)h(>0.)g(Nodes)f(having)g(varlevelsup)g(>)g(0)h(are)664
1250 y(*)f(forgotten)g(to)h(be)g(processed.)e(The)i(call)f(to)664
1310 y(*)g(OffsetVarNodes\(\))f(should)i(really)f(be)g(done)h(at)664
1370 y(*)f(another)g(place)h(but)f(this)h(hack)f(makes)g(sure)664
1430 y(*)g(that)h(also)f(those)h(VAR)f(nodes)g(are)h(processed.)664
1489 y(*/)395 1549 y(+)209 b(if)29 b(\(var->varlevelsup)f(>)i(0\))395
1609 y(+)298 b(OffsetVarNodes\(\(Node)28 b(*\)var,3\);)574
1669 y(})574 1729 y(break;)1231 1788 y(.)1231 1848 y(.)1231
1908 y(.)574 1968 y(case)h(T_SubLink:)574 2027 y({)1231
2087 y(.)1231 2147 y(.)1231 2207 y(.)395 2267 y(+)209
b(ChangeVarNodes\(\(Node)27 b(*\))j(query->havingQual,)395
2326 y(+)657 b(old_varno,)29 b(new_varno,)395 2386 y(+)657
b(sublevels_up\);)395 2446 y(+)209 b(ChangeVarNodes\(\(Node)27
b(*\))j(query->targetList,)395 2506 y(+)657 b(old_varno,)29
b(new_varno,)395 2565 y(+)657 b(sublevels_up\);)395 2625
y(+)395 2685 y(+)209 b(/*)29 b(We)h(also)f(have)h(to)g(adapt)f(the)g
(variables)g(used)h(in)395 2745 y(+)239 b(*)29 b(sublink->lefthand)f
(and)i(sublink->oper)395 2804 y(+)239 b(*/)395 2864 y(+)209
b(ChangeVarNodes\(\(Node)27 b(*\))j(\(sublink->lefthand\),)395
2924 y(+)657 b(old_varno,)29 b(new_varno,)395 2984 y(+)657
b(sublevels_up\);)574 3044 y(})574 3103 y(break;)1231
3163 y(.)1231 3223 y(.)1231 3283 y(.)514 3342 y(})454
3402 y(})p eop
%%Page: 77 77
77 76 bop 198 60 a Fm(3.7.)26 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)625 b Ft(77)273
234 y Fo(\017)25 b Fr(AddHavingQual\(\))323 294 y Ft(This)17
b(function)f(adds)h(the)g Fp(oper)o(ator)g(tr)n(ee)h
Ft(gi)o(v)o(en)e(by)h(the)g(parameter)f Fr(havingQual)g
Ft(to)g(the)323 354 y(one)k(attached)g(to)g(the)g(\002eld)g
Fr(havingQual)f Ft(of)h(the)g Fp(parsetr)n(ee)i Ft(gi)o(v)o(en)e(by)g
(the)g(parameter)323 413 y Fr(parsetree)p Ft(.)28 b(This)17
b(is)g(done)g(by)g(adding)f(a)h(ne)o(w)g Fr(AND)g Ft(node)f(and)h
(attaching)g(the)g(old)f(and)323 473 y(the)d(ne)o(w)h
Fp(oper)o(ator)h(tr)n(ee)f Ft(as)h(ar)o(guments)f(to)f(it.)21
b Fr(AddHavingQual\(\))12 b Ft(has)i(not)g(been)g(e)o(xist-)323
533 y(ing)e(until)f(v6.3.2.)17 b(It)12 b(has)h(been)f(created)g(for)g
(the)g Fp(having)g(logic)p Ft(.)382 667 y Fr(void)382
727 y(AddHavingQual\(Query)28 b(*parsetree,)h(Node)g(*havingQual\))382
787 y({)442 847 y(Node)59 b(*copy,)30 b(*old;)442 966
y(if)g(\(havingQual)e(==)i(NULL\))532 1026 y(return;)442
1146 y(copy)g(=)f(havingQual;)442 1265 y(old)h(=)f
(parsetree->havingQual;)442 1325 y(if)h(\(old)f(==)h(NULL\))562
1385 y(parsetree->havingQual)d(=)j(copy;)442 1445 y(else)562
1504 y(parsetree->havingQual)d(=)681 1564 y(\(Node)j(*\))f
(make_andclause\()1010 1624 y(makeList\(parsetree->havingQual,)1279
1684 y(copy,)g(-1\)\);)382 1743 y(})273 1878 y Fo(\017)c
Fr(AddNotHavingQual\(\))323 1938 y Ft(This)17 b(function)f(is)i
(similar)e(to)h(the)g(abo)o(v)o(e)h(described)f(function)f
Fr(AddHavingQual\(\))p Ft(.)29 b(It)323 1998 y(also)14
b(adds)g(the)f Fp(oper)o(ator)i(tr)n(ee)f Ft(gi)o(v)o(en)g(by)f(the)h
(parameter)f Fr(havingQual)f Ft(b)o(ut)i(pre\002x)o(es)g(it)f(by)323
2057 y(a)h Fr(NOT)g Ft(node.)22 b Fr(AddNotHavingQual\(\))13
b Ft(has)i(also)g(not)f(been)h(e)o(xisting)f(until)g(v6.3.2)h(and)323
2117 y(has)d(been)h(created)f(for)g(the)g Fp(having)g(logic)p
Ft(.)382 2252 y Fr(void)382 2311 y(AddNotHavingQual\(Query)28
b(*parsetree,)890 2371 y(Node)i(*havingQual\))382 2431
y({)442 2491 y(Node)g(*copy;)442 2610 y(if)g(\(havingQual)e(==)i
(NULL\))532 2670 y(return;)442 2790 y(copy)g(=)f(\(Node)h(*\))f
(make_notclause\(\(Expr)f(*\)havingQual\);)442 2849 y
(AddHavingQual\(parsetree,)f(copy\);)323 2909 y(})273
3044 y Fo(\017)e Fr(nodeHandleViewRule\(\))323 3103 y
Ft(This)20 b(function)f(is)h(called)g(by)g Fr(HandleViewRule\(\))p
Ft(.)36 b(It)20 b(replaces)g(all)g Fr(VAR)f Ft(nodes)i(of)323
3163 y(the)16 b Fp(user)i(query)f Ft(e)o(v)o(aluated)f(against)g(the)h
Fp(vie)o(w)g Ft(\(the)f(\002elds)h(of)f(these)h Fr(VAR)g
Ft(nodes)f(represent)323 3223 y(the)g(positions)h(of)f(the)g(attrib)o
(utes)g(in)h(the)f Fp(virtual)h Ft(table\))f(by)g Fr(VAR)g
Ft(nodes)h(that)f(ha)o(v)o(e)h(already)323 3283 y(been)c(prepared)g(to)
h(represent)f(the)h(positions)g(of)f(the)h(corresponding)f(attrib)o
(utes)g(in)g(the)h Fp(phys-)323 3342 y(ical)h Ft(tables)h(\(gi)o(v)o
(en)f(in)h(the)g Fp(vie)o(w)g(de\002nition)p Ft(\).)25
b(The)16 b(additional)f(statements)h(make)f(sure)h(that)323
3402 y Fr(GroupClause)11 b Ft(nodes)h(and)h Fr(Sublink)e
Ft(nodes)i(are)f(handled)h(correctly)m(.)p eop
%%Page: 78 78
78 77 bop 270 60 a Ft(78)85 b Fm(CHAPTER)14 b(3.)25 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)454
234 y Fr(static)30 b(void)454 294 y(nodeHandleViewRule\(Node)e
(**nodePtr,)g(List)i(*rtable,)1022 354 y(List)g(*targetlist,)e(int)i
(rt_index,)1022 413 y(int)g(*modified,)e(int)i(sublevels_up\))454
473 y({)514 533 y(Node)g(*node)f(=)h(*nodePtr;)514 593
y(if)g(\(node)f(==)h(NULL\))604 653 y(return;)514 712
y(switch)f(\(nodeTag\(node\)\))514 772 y({)1231 832 y(.)1231
892 y(.)1231 951 y(.)395 1011 y(+)149 b(/*)30 b(This)f(has)h(to)f(be)h
(done)f(to)h(make)f(queries)g(using)395 1071 y(+)179
b(*)30 b(groupclauses)e(work)i(on)f(views)395 1131 y(+)179
b(*/)395 1191 y(+)149 b(case)29 b(T_GroupClause:)395
1250 y(+)149 b({)395 1310 y(+)209 b(GroupClause)58 b(*group)29
b(=)h(\(GroupClause)f(*\))g(node;)395 1370 y(+)209 b
(nodeHandleViewRule\(\(Node)27 b(**\))i(\(&\(group->entry\)\),)395
1430 y(+)777 b(rtable,)29 b(targetlist,)f(rt_index,)395
1489 y(+)777 b(modified,)28 b(sublevels_up\);)395 1549
y(+)149 b(})395 1609 y(+)g(break;)1231 1669 y(.)1231
1729 y(.)1231 1788 y(.)574 1848 y(case)29 b(T_Var:)574
1908 y({)1231 1968 y(.)1231 2027 y(.)1231 2087 y(.)634
2147 y(if)g(\(n)h(==)g(NULL\))634 2207 y({)693 2267 y(*nodePtr)f(=)h
(make_null\(\(\(Var)e(*\)node\)->vartype\);)634 2326
y(})634 2386 y(else)395 2446 y(+)209 b(/*)29 b(This)h(is)f(a)h(hack:)g
(The)f(varlevelsup)g(of)g(the)395 2506 y(+)239 b(*)29
b(original)g(variable)g(and)h(the)f(new)h(one)f(should)395
2565 y(+)239 b(*)29 b(be)h(the)g(same.)f(Normally)g(we)g(adapt)h(the)f
(node)395 2625 y(+)239 b(*)29 b(by)h(changing)f(a)h(pointer)f(to)g
(point)h(to)f(a)h(var)395 2685 y(+)239 b(*)29 b(contained)g(in)h
('targetlist'.)e(In)i(the)395 2745 y(+)239 b(*)29 b(targetlist)g(all)h
(varlevelsups)e(are)i(0)f(so)h(if)395 2804 y(+)239 b(*)29
b(we)h(want)f(to)h(change)f(it)h(to)g(the)f(original)395
2864 y(+)239 b(*)29 b(value)h(we)f(have)h(to)f(copy)h(the)f(node)h
(before!)395 2924 y(+)239 b(*)29 b(\(Maybe)h(this)f(will)g(cause)h
(troubles)f(with)g(some)395 2984 y(+)239 b(*)29 b(sophisticated)g
(queries)g(on)g(views?\))395 3044 y(+)239 b(*/)395 3103
y(+)209 b({)395 3163 y(+)268 b(if\(this_varlevelsup>0\))395
3223 y(+)g({)395 3283 y(+)358 b(*nodePtr)29 b(=)h(copyObject\(n\);)395
3342 y(+)268 b(})395 3402 y(+)g(else)p eop
%%Page: 79 79
79 78 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(79)323
234 y Fr(+)268 b({)323 294 y(+)328 b(*nodePtr)29 b(=)h(n;)323
354 y(+)268 b(})323 413 y(+)g(\(\(Var)30 b(*\)*nodePtr\)->varlevelsup)d
(=)323 473 y(+)836 b(this_varlevelsup;)323 533 y(+)209
b(})562 593 y(*modified)29 b(=)g(TRUE;)502 653 y(})502
712 y(break;)1159 772 y(.)1159 832 y(.)1159 892 y(.)502
951 y(case)g(T_SubLink:)502 1011 y({)1159 1071 y(.)1159
1131 y(.)1159 1191 y(.)323 1250 y(+)209 b(nodeHandleViewRule\()323
1310 y(+)508 b(\(Node)29 b(**\))g(&\(query->havingQual\),)323
1370 y(+)508 b(rtable,)29 b(targetlist,)f(rt_index,)323
1430 y(+)508 b(modified,)28 b(sublevels_up\);)323 1489
y(+)209 b(nodeHandleViewRule\()323 1549 y(+)508 b(\(Node)29
b(**\))g(&\(query->targetList\),)323 1609 y(+)508 b(rtable,)29
b(targetlist,)f(rt_index,)323 1669 y(+)508 b(modified,)28
b(sublevels_up\);)323 1729 y(+)209 b(/*)29 b(We)h(also)f(have)h(to)g
(adapt)f(the)g(variables)g(used)323 1788 y(+)239 b(*)29
b(in)h(sublink->lefthand)e(and)h(sublink->oper)323 1848
y(+)239 b(*/)323 1908 y(+)209 b(nodeHandleViewRule\()323
1968 y(+)508 b(\(Node)29 b(**\))g(&\(sublink->lefthand\),)323
2027 y(+)508 b(rtable,)29 b(targetlist,)f(rt_index,)323
2087 y(+)508 b(modified,)28 b(sublevels_up\);)323 2147
y(+)209 b(/*)29 b(Make)h(sure)f(the)h(first)f(argument)g(of)323
2207 y(+)239 b(*)29 b(sublink->oper)g(points)g(to)h(the)f(same)h(var)f
(as)323 2267 y(+)239 b(*)29 b(sublink->lefthand)f(does)i(otherwise)f
(we)g(will)323 2326 y(+)239 b(*)29 b(run)h(into)f(troubles)g(using)h
(aggregates)323 2386 y(+)239 b(*)29 b(\(aggno)h(will)f(not)h(be)f(set)h
(correctly!\))323 2446 y(+)239 b(*/)323 2506 y(+)209
b(pfree\(lfirst\(\(\(Expr)27 b(*\))323 2565 y(+)597 b
(lfirst\(sublink->oper\)\)->args\)\);)323 2625 y(+)209
b(tmp_lefthand)28 b(=)i(sublink->lefthand;)323 2685 y(+)209
b(foreach\(tmp_oper,)28 b(sublink->oper\))323 2745 y(+)209
b({)323 2804 y(+)298 b(lfirst\(\(\(Expr)29 b(*\))g
(lfirst\(tmp_oper\)\)->args\))f(=)323 2864 y(+)1016 b
(lfirst\(tmp_lefthand\);)323 2924 y(+)298 b(tmp_lefthand)29
b(=)h(lnext\(tmp_lefthand\);)323 2984 y(+)209 b(})502
3044 y(})502 3103 y(break;)1159 3163 y(.)1159 3223 y(.)1159
3283 y(.)442 3342 y(})382 3402 y(})p eop
%%Page: 80 80
80 79 bop 270 60 a Ft(80)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)345
234 y Fo(\017)25 b Fr(HandleViewRule\(\))395 294 y Ft(This)11
b(function)g(calls)g Fr(nodeHandleViewRule\(\))f Ft(for)g(the)h
Fp(wher)n(e)h(clause)p Ft(,)h(the)e Fp(tar)n(getlist)p
Ft(,)395 354 y(the)h Fp(gr)n(oup)g(clause)h Ft(and)f(the)h
Fp(having)f(clause)g Ft(of)g(the)h Fp(user)g(query)g
Ft(e)o(v)o(aluated)f(against)g(the)g(gi)o(v)o(en)395
413 y Fp(vie)o(w)p Ft(.)454 537 y Fr(void)454 597 y
(HandleViewRule\(Query)28 b(*parsetree,)h(List)g(*rtable,)903
656 y(List)g(*targetlist,)g(int)g(rt_index,)903 716 y(int)g
(*modified\))454 776 y({)1231 836 y(.)1231 895 y(.)1231
955 y(.)395 1015 y(+)89 b(/*)30 b(The)f(variables)g(in)h(the)f
(havingQual)g(and)395 1075 y(+)119 b(*)30 b(groupClause)e(also)i(have)f
(to)h(be)g(adapted)395 1135 y(+)119 b(*/)395 1194 y(+)89
b(nodeHandleViewRule\(&parsetree->h)o(avingQual)o(,)27
b(rtable,)395 1254 y(+)657 b(targetlist,)29 b(rt_index,)395
1314 y(+)657 b(modified,)29 b(0\);)395 1374 y(+)89 b
(nodeHandleViewRule\()395 1433 y(+)328 b(\(Node)30 b
(**\)\(&\(parsetree->groupClaus)o(e\)\),)395 1493 y(+)328
b(rtable,)29 b(targetlist,)g(rt_index,)g(modified,)g(0\);)454
1553 y(})270 1676 y Ft(The)13 b(follo)o(wing)e(function)g(is)i
(contained)f(in)g Fk(:)c(:)g(:)p Fr(/src/backend/commands/view.c)p
Ft(:)345 1790 y Fo(\017)25 b Fr(UpdateRangeTableOfViewParse\()o(\))395
1849 y Ft(This)f(function)f(updates)h(the)g Fp(r)o(ange)g(table)f
Ft(of)g(the)h Fp(parsetr)n(ee)h Ft(gi)o(v)o(en)e(by)h(the)g(parameter)
395 1909 y Fr(viewParse)p Ft(.)14 b(The)e(additional)e(statement)h
(makes)g(sure)g(that)g(the)g Fr(VAR)g Ft(nodes)g(of)f(the)h
Fp(having)395 1969 y(clause)h Ft(are)h(modi\002ed)e(in)h(the)h(same)f
(way)g(as)h(the)g Fr(VAR)f Ft(nodes)g(of)g(the)h Fp(wher)n(e)g(clause)g
Ft(are.)454 2092 y Fr(static)30 b(void)454 2152 y
(UpdateRangeTableOfViewParse\(char)d(*viewName,)1291
2212 y(Query)i(*viewParse\))454 2272 y({)1231 2331 y(.)1231
2391 y(.)1231 2451 y(.)514 2511 y(OffsetVarNodes\(viewParse->qual,)d
(2\);)395 2630 y(+)89 b(OffsetVarNodes\(viewParse->having)o(Qual,)27
b(2\);)1231 2690 y(.)1231 2750 y(.)1231 2810 y(.)454
2869 y(})270 3007 y Fn(Planner/Optimizer)270 3102 y Ft(The)18
b Fp(planner)g Ft(b)o(uilds)f(a)h Fp(queryplan)g Ft(like)e(the)i(one)f
(sho)o(wn)h(in)f(\002gure)g(3.8)h(and)g(in)f(addition)g(to)g(that)270
3162 y(it)f(takes)g(the)g Fp(oper)o(ator)h(tr)n(ee)g
Ft(attached)f(to)g(the)g(\002eld)g Fr(havingClause)f
Ft(of)g(the)h Fr(Query)g Ft(node)g(and)270 3222 y(attaches)d(is)g(to)f
(the)g Fr(qpqual)g Ft(\002eld)g(of)g(the)g Fr(AGG)g Ft(node.)345
3283 y(Unfortunately)18 b(this)i(is)g(not)f(the)g(only)h(thing)f(to)g
(do.)38 b(Remember)19 b(from)g(section)h(3.7.1)g Fp(How)270
3342 y(Aggr)n(e)n(gate)11 b(Functions)g(ar)n(e)g(Implemented)f
Ft(that)g(the)h Fp(tar)n(getlist)f Ft(is)h(searched)g(for)f
Fp(aggr)n(e)n(gate)f(functions)270 3402 y Ft(which)k(are)g(appended)g
(to)g(a)g(list)g(that)g(will)g(be)g(attached)g(to)g(the)g(\002eld)g
Fr(aggs)g Ft(of)g(the)g Fr(AGG)f Ft(node.)18 b(This)p
eop
%%Page: 81 81
81 80 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(81)198
234 y(was)14 b(suf)o(\002cient)f(as)i(long)e(as)i Fp(aggr)n(e)n(gate)e
(functions)h Ft(ha)o(v)o(e)g(only)g(been)g(allo)o(wed)f(to)h(appear)g
(within)f(the)198 294 y Fp(tar)n(getlist)p Ft(.)24 b(No)o(w)16
b(the)f Fp(having)g(clause)h Ft(is)f(another)g(source)h(of)f
Fp(aggr)n(e)n(gate)f(functions)p Ft(.)25 b(Consider)15
b(the)198 354 y(follo)o(wing)c(e)o(xample:)258 459 y
Fr(select)29 b(sno,)g(max\(pno\))258 519 y(from)g(sells)258
579 y(group)g(by)h(sno)258 638 y(having)f(count\(pno\))g(>)h(1;)198
742 y Ft(Here)14 b(the)g Fp(aggr)n(e)n(gate)f(functions)h
Fr(max)g Ft(and)g Fr(count)g Ft(are)g(in)g(use.)21 b(If)14
b(only)f(the)h Fp(tar)n(getlist)g Ft(is)h(scanned)198
802 y(\(as)f(it)g(was)g(the)f(case)i(before)e(the)h Fp(having)g(clause)
g Ft(had)g(been)g(implemented\))f(we)h(will)f(only)h(\002nd)f(and)198
862 y(process)18 b(the)g Fp(aggr)n(e)n(gate)g(function)f
Fr(max)p Ft(.)32 b(The)19 b(second)f(function)f Fr(count)h
Ft(is)g(not)g(processed)g(and)198 922 y(therefore)f(an)o(y)i(reference)
f(to)g(the)g(result)g(of)g Fr(count)g Ft(from)g(within)f(the)i
Fp(having)f(clause)h Ft(will)f(fail.)198 981 y(The)g(solution)g(to)f
(this)h(problem)f(is)h(to)g(scan)g(the)g(whole)g Fp(oper)o(ator)g(tr)n
(ee)h Ft(representing)e(the)g Fp(having)198 1041 y(clause)12
b Ft(for)g Fp(aggr)n(e)n(gate)f(functions)h Ft(not)f(contained)h(in)g
(the)g Fp(tar)n(getlist)g Ft(yet)g(and)g(add)g(them)g(to)f(the)h(list)h
(of)198 1101 y Fp(aggr)n(e)n(gate)g(functions)g Ft(attached)h(to)f(the)
h(\002eld)f Fr(aggs)g Ft(of)h(the)f Fr(AGG)g Ft(node.)20
b(The)14 b(scanning)g(is)g(done)f(by)198 1161 y(the)18
b(function)f Fr(check)p 614 1161 15 2 v 18 w(having)p
812 1161 V 17 w(qual)p 949 1161 V 17 w(for)p 1056 1161
V 18 w(aggs\(\))h Ft(which)g(steps)g(recursi)o(v)o(ely)g(through)f(the)
198 1220 y(tree.)198 1340 y(While)25 b(scanning)h(the)g
Fp(having)f(clause)h Ft(for)f Fp(aggr)n(e)n(gate)g(functions)g
Ft(not)h(contained)f(in)h(the)f Fp(tar)o(-)198 1400 y(getlist)18
b Ft(yet,)j(an)e(additional)f(check)h(is)g(made)g(to)g(make)f(sure)h
(that)f Fp(aggr)n(e)n(gate)g(functions)h Ft(are)g(used)198
1460 y(within)12 b(the)g Fp(having)g(clause)g Ft(\(otherwise)g(the)g
(query)g(could)g(ha)o(v)o(e)g(been)h(formulated)e(using)h(the)g
Fp(wher)n(e)198 1519 y(clause)p Ft(\).)k(Consider)c(the)g(follo)o(wing)
f(query)h(which)g(is)h(not)f(a)h(v)o(alid)f(SQL92)g(query:)258
1625 y Fr(testdb=>)29 b(select)g(sno,)g(max\(pno\))258
1684 y(testdb->)g(from)g(sells)258 1744 y(testdb->)g(group)g(by)h(sno)
258 1804 y(testdb->)f(having)g(sno)h(>)f(1;)258 1864
y(ERROR:)59 b(This)29 b(could)h(have)f(been)h(done)f(in)h(a)f(where)h
(clause!!)258 1924 y(testdb=>)198 2027 y Ft(There)19
b(is)f(no)g(need)h(to)f(e)o(xpress)h(this)f(query)g(using)h(a)f
Fp(having)g(clause)p Ft(,)j(this)d(kind)g(of)g(quali\002cation)198
2087 y(belongs)12 b(to)h(the)f Fp(wher)n(e)h(clause)p
Ft(:)258 2192 y Fr(select)29 b(sno,)g(max\(pno\))258
2252 y(from)g(sells)258 2312 y(where)g(sno)h(>)f(1)258
2372 y(group)g(by)h(sno;)198 2476 y Ft(There)17 b(is)g(still)f(an)g
(unsolv)o(ed)h(problem)f(left.)27 b(Consider)17 b(the)f(follo)o(wing)f
(query)h(where)h(we)f(want)g(to)198 2535 y(kno)o(w)c(just)g(the)h
(supplier)f(numbers)g(\()p Fr(sno)p Ft(\))f(of)h(all)g(suppliers)g
(selling)h(more)f(than)g(one)g(part:)258 2641 y Fr(select)29
b(sno)258 2701 y(from)g(sells)258 2760 y(group)g(by)h(sno)258
2820 y(having)f(count\(pno\))g(>)h(1;)198 2924 y Ft(The)14
b Fp(planner)f Ft(creates)g(a)h Fp(queryplan)f Ft(\(like)f(the)h(one)g
(sho)o(wn)g(in)g(\002gure)f(3.8\))h(where)g(the)g Fp(tar)n(getlists)h
Ft(of)198 2984 y(all)e(nodes)f(in)n(v)o(olv)o(ed)h(contain)f(only)g
(entries)h(of)f(those)h(attrib)o(utes)f(listed)h(after)f(the)g
Fr(select)g Ft(ke)o(yword)198 3044 y(of)18 b(the)h(query)m(.)35
b(Looking)19 b(at)f(the)h(e)o(xample)g(abo)o(v)o(e)h(this)f(means)g
(that)f(the)h Fp(tar)n(getlists)g Ft(of)g(the)f Fr(AGG)198
3103 y Ft(node,)c(the)f Fr(GRP)f Ft(node)h(the)g Fr(SORT)g
Ft(node)g(and)g(the)g Fr(SeqScan)f Ft(node)h(contain)g(only)g(the)f
(entry)h(for)f(the)198 3163 y(attrib)o(ute)d Fr(sno)p
Ft(.)15 b(As)c(described)f(earlier)g(the)g Fp(aggr)n(e)n(gation)f
(logic)h Ft(operates)g(on)g(attrib)o(utes)g(of)g(the)g(tuples)198
3223 y(returned)h(by)g(the)h(subplan)g(of)f(the)h Fr(AGG)f
Ft(node)h(\(i.e.)j(the)d(result)g(of)f(the)g Fr(GRP)h
Ft(node\).)j(Which)d(attrib)o(utes)198 3283 y(are)17
b(contained)f(in)g(the)h(tuples)g(handed)f(back)h(by)g(a)g(subplan)f
(is)h(determined)f(by)h(the)f Fp(tar)n(getlist)p Ft(.)29
b(In)198 3342 y(the)13 b(case)h(of)e(our)h(e)o(xample)g(the)f(attrib)o
(ute)g Fr(pno)h Ft(needed)g(for)f(the)h Fp(aggr)n(e)n(gate)f(function)h
Fr(count)f Ft(is)h(not)198 3402 y(included)f(and)g(therefore)g(the)g
Fp(aggr)n(e)n(gation)f Ft(will)h(fail.)p eop
%%Page: 82 82
82 81 bop 270 60 a Ft(82)85 b Fm(CHAPTER)14 b(3.)25 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(The)h(solution)f(to)g(this)h(problem)e(is)i(gi)o(v)o(en)f(in)g
(the)g(follo)o(wing)f(steps:)345 334 y Fo(\017)25 b Ft(Make)12
b(a)g(copy)g(of)g(the)h(actual)f Fp(tar)n(getlist)g Ft(of)g(the)g
Fr(AGG)g Ft(node.)345 433 y Fo(\017)25 b Ft(Search)17
b(the)h Fp(oper)o(ator)h(tr)n(ee)g Ft(representing)e(the)h
Fp(having)g(clause)h Ft(for)e(attrib)o(utes)g(that)h(are)g(not)395
493 y(contained)12 b(in)h(the)g Fp(tar)n(getlist)f Ft(of)h(the)g
Fr(AGG)f Ft(node)h(yet)g(and)g(add)g(them)f(to)h(the)g(pre)o(viously)f
(made)395 553 y(copy)m(.)345 653 y Fo(\017)25 b Ft(The)12
b(e)o(xtended)f Fp(tar)n(getlist)g Ft(is)h(used)g(to)f(create)h(the)f
(subplan)h(attached)f(to)g(the)h Fr(lefttree)e Ft(\002eld)395
712 y(of)18 b(the)h Fr(AGG)f Ft(node.)35 b(That)19 b(means)g(that)g
(the)f Fp(tar)n(getlists)h Ft(of)g(the)f Fr(GRP)h Ft(node,)h(of)f(the)f
Fr(SORT)395 772 y Ft(node)g(and)g(of)f(the)h Fr(SeqScan)g
Ft(node)g(will)f(no)o(w)h(contain)g(an)g(entry)f(for)h(the)g(attrib)o
(ute)f Fr(pno)p Ft(.)395 832 y(The)c Fp(tar)n(getlist)g
Ft(of)g(the)g Fr(AGG)g Ft(node)g(itself)g(will)g(not)g(be)h(changed)f
(because)h(we)f(do)h(not)f(want)f(to)395 892 y(include)g(the)g(attrib)o
(ute)f Fr(pno)i Ft(into)f(the)g(result)g(returned)f(by)i(the)f(whole)g
(query)m(.)270 991 y(Care)17 b(has)g(to)f(be)h(taken)f(that)h(the)f
Fr(varattno)g Ft(\002elds)h(of)f(the)h Fr(VAR)f Ft(nodes)h(used)g(in)f
(the)h Fp(tar)n(getlists)270 1051 y Ft(contain)e(the)h(position)f(of)g
(the)h(corresponding)e(attrib)o(ute)h(in)g(the)h Fp(tar)n(getlist)f
Ft(of)g(the)h(subplan)f(\(i.e)h(the)270 1111 y(subplan)c(deli)o(v)o
(ering)g(the)g(tuples)h(for)e(further)g(processing)i(by)f(the)g(actual)
h(node\).)270 1230 y(The)23 b(follo)o(wing)e(part)h(deals)g(with)g(the)
h(source)f(code)h(of)f(the)g(ne)o(w)g(and)g(changed)h(functions)f(in-)
270 1290 y(v)o(olv)o(ed)12 b(in)h(the)f(planner/optimizer)e(stage.)17
b(The)c(\002les)f(af)o(fected)g(are:)345 1410 y Fk(:)c(:)g(:)p
Fr(/src/backend/optimizer/plan/se)o(trefs.c)345 1469
y Fk(:)g(:)g(:)p Fr(/src/backend/optimizer/plan/pl)o(anner.c)270
1589 y Ft(Since)25 b(all)f(of)h(the)g(functions)f(presented)h(here)g
(are)f(v)o(ery)h(long)g(and)g(would)f(need)h(v)o(ery)f(much)270
1649 y(space)13 b(if)f(presented)g(as)h(a)g(whole,)f(we)h(just)f(list)h
(the)f(most)g(important)g(parts.)270 1768 y(The)23 b(follo)o(wing)e
(two)g(functions)h(are)g(ne)o(w)g(and)g(ha)o(v)o(e)h(been)f(introduced)
g(for)f(the)h Fp(having)g(logic)p Ft(.)270 1828 y(The)o(y)13
b(are)f(contained)g(in)h(the)f(\002le)g Fk(:)c(:)g(:)p
Fr(/src/backend/optimizer/plan/setref)o(s.c)p Ft(:)345
1928 y Fo(\017)25 b Fr(check)p 548 1928 15 2 v 17 w(having)p
745 1928 V 17 w(qual)p 882 1928 V 18 w(for)p 990 1928
V 17 w(aggs\(\))395 1988 y Ft(This)19 b(function)g(takes)g(the)g
(representation)f(of)h(a)g Fp(having)g(clause)h Ft(gi)o(v)o(en)f(by)g
(the)g(parameter)395 2047 y Fr(clause)p Ft(,)14 b(a)h
Fp(tar)n(getlist)f Ft(gi)o(v)o(en)h(by)f(the)h(parameter)e
Fr(subplanTargetList)g Ft(and)i(a)f Fp(gr)n(oup)395 2107
y(clause)j Ft(gi)o(v)o(en)h(by)f(the)g(parameter)g Fr(groupClause)f
Ft(as)j(ar)o(guments)e(and)g(scans)i(the)e(repre-)395
2167 y(sentation)e(of)g(the)h Fp(having)g(clause)g Ft(recursi)o(v)o
(ely)f(for)g Fp(aggr)n(e)n(gate)g(functions)p Ft(.)25
b(If)15 b(an)h Fp(aggr)n(e)n(gate)395 2227 y(function)i
Ft(is)h(found)f(it)g(is)h(attached)g(to)g(a)g(list)f(\(internally)g
(called)g Fr(agg)p 1682 2227 V 18 w(list)p Ft(\))g(and)h(\002nally)395
2286 y(returned)11 b(by)h(the)h(function.)395 2366 y(Additionally)g
(the)i Fr(varno)f Ft(\002eld)g(of)g(e)o(v)o(ery)h Fr(VAR)f
Ft(node)h(found)f(is)h(set)g(to)f(the)h(position)f(of)g(the)395
2426 y(corresponding)d(attrib)o(ute)g(in)i(the)f Fp(tar)n(getlist)g
Ft(gi)o(v)o(en)g(by)g Fr(subplanTargetList)p Ft(.)395
2506 y(If)17 b(the)h Fp(having)f(clause)h Ft(contains)g(a)g(subquery)g
(the)g(function)f(also)h(makes)g(sure,)i(that)d(e)o(v)o(ery)395
2565 y(attrib)o(ute)f(from)f(the)i Fp(main)g(query)g
Ft(that)g(is)g(used)g(within)g(the)f(subquery)h(also)g(appears)g(in)g
(the)395 2625 y Fp(gr)n(oup)11 b(clause)i Ft(gi)o(v)o(en)e(by)h
Fr(groupClause)p Ft(.)j(If)c(the)h(attrib)o(ute)f(cannot)h(be)g(found)f
(in)h(the)g Fp(gr)n(oup)395 2685 y(clause)g Ft(an)h(error)e(message)i
(is)g(printed)e(to)i(the)f(screen)h(and)f(the)g(query)g(processing)h
(is)f(aborted.)454 2804 y Fr(List)30 b(*)454 2864 y
(check_having_qual_for_aggs\(Node)d(*clause,)1261 2924
y(List)j(*subplanTargetList,)1261 2984 y(List)g(*groupClause\))454
3044 y({)514 3103 y(List)g(*t,)f(*l1;)514 3163 y(List)h(*agg_list)e(=)i
(NIL;)514 3223 y(int)60 b(contained_in_group_clause)27
b(=)i(0;)514 3342 y(if)h(\(IsA\(clause,)e(Var\)\))514
3402 y({)p eop
%%Page: 83 83
83 82 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(83)502
234 y Fr(TargetEntry)29 b(*subplanVar;)502 354 y(subplanVar)g(=)g
(match_varid\(\(Var)f(*\))i(clause,)1249 413 y(subplanTargetList\);)502
473 y(/*)g(Change)f(the)g(varattno)g(fields)g(of)h(the)532
533 y(*)g(var)f(node)h(to)f(point)h(to)f(the)h(resdom->resnofields)532
593 y(*)g(of)f(the)h(subplan)f(\(lefttree\))532 653 y(*/)502
712 y(\(\(Var)g(*\))h(clause\)->varattno)e(=)562 772
y(subplanVar->resdom->resno;)502 832 y(return)h(NIL;)442
892 y(})442 951 y(else)502 1011 y(if)h(\(is_funcclause\(clause\))d(||)j
(not_clause\(clause\))621 1071 y(||)g(or_clause\(clause\))e(||)i
(and_clause\(clause\)\))502 1131 y({)562 1191 y(int)f(new_length=0,)g
(old_length=0;)562 1310 y(/*)g(This)h(is)f(a)h(function.)f(Recursively)
g(call)g(this)592 1370 y(*)g(routine)g(for)h(its)g(arguments...)e
(\(i.e.)h(for)h(AND,)592 1430 y(*)f(OR,)h(...)f(clauses!\))592
1489 y(*/)562 1549 y(foreach\(t,)f(\(\(Expr)i(*\))f(clause\)->args\))
562 1609 y({)621 1669 y(old_length=length\(\(List)f(*\)agg_list\);)621
1729 y(agg_list)h(=)h(nconc\(agg_list,)741 1788 y
(check_having_qual_for_aggs\(lfir)o(st\(t\),)1309 1848
y(subplanTargetList,)1309 1908 y(groupClause\)\);)621
1968 y(if\(\(\(new_length=length\(\(List)d(*\)agg_list\)\))i(==)741
2027 y(old_length\))g(||)g(\(new_length)g(==)h(0\)\))621
2087 y({)681 2147 y(elog\(ERROR,"This)e(could)i(have)f(been)g(done)1309
2207 y(in)g(a)h(where)g(clause!!"\);)681 2267 y(return)f(NIL;)621
2326 y(})562 2386 y(})562 2446 y(return)g(agg_list;)502
2506 y(})502 2565 y(else)562 2625 y(if)g(\(IsA\(clause,)g(Aggreg\)\))
562 2685 y({)621 2745 y(return)h(lcons\(clause,)1040
2804 y(check_having_qual_for_aggs\()1159 2864 y(\(\(Aggreg)f
(*\)clause\)->target,)1159 2924 y(subplanTargetList,)1159
2984 y(groupClause\)\);)562 3044 y(})562 3103 y(else)1159
3163 y(.)1159 3223 y(.)1159 3283 y(.)382 3342 y(})p eop
%%Page: 84 84
84 83 bop 270 60 a Ft(84)85 b Fm(CHAPTER)14 b(3.)25 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)345
234 y Fo(\017)25 b Fr(check)p 548 234 15 2 v 17 w(having)p
745 234 V 17 w(qual)p 882 234 V 18 w(for)p 990 234 V
17 w(vars\(\))395 294 y Ft(This)19 b(function)g(takes)g(the)g
(representation)f(of)h(a)g Fp(having)g(clause)h Ft(gi)o(v)o(en)f(by)g
(the)g(parameter)395 354 y Fr(clause)11 b Ft(and)h(the)g(actual)h
Fp(tar)n(getlist)e Ft(gi)o(v)o(en)h(by)h(the)f(parameter)f
Fr(targetlist)p 1835 354 V 17 w(so)p 1912 354 V 18 w(far)h
Ft(as)395 413 y(ar)o(guments)e(and)h(recursi)o(v)o(ely)f(scans)i(the)e
(representation)g(of)h(the)f Fp(having)h(clause)g Ft(for)f(attrib)o
(utes)395 473 y(that)i(are)g(not)h(included)f(in)g(the)h(actual)f
Fp(tar)n(getlist)g Ft(yet.)k(Whene)o(v)o(er)d(such)g(an)f(attrib)o(ute)
g(is)h(found)395 533 y(it)f(is)g(added)h(to)f(the)g(actual)h
Fp(tar)n(getlist)f Ft(which)g(is)h(\002nally)e(returned)h(by)g(the)g
(function.)395 611 y(Attrib)o(utes)20 b(contained)h(in)g(the)g
Fp(having)g(clause)g Ft(b)o(ut)g(not)g(in)g(the)g Fp(tar)n(getlist)f
Ft(sho)o(w)h(up)g(with)395 671 y(queries)12 b(like:)454
785 y Fr(select)30 b(sid)454 844 y(from)60 b(part)454
904 y(group)30 b(by)f(sid)454 964 y(having)h(min\(pid\))f(>)g(1;)395
1077 y Ft(In)9 b(the)g(abo)o(v)o(e)h(query)f(the)g(attrib)o(ute)g
Fr(pid)g Ft(is)h(used)f(in)h(the)f Fp(having)g(clause)h
Ft(b)o(ut)f(it)g(does)h(not)f(appear)395 1137 y(in)j(the)h
Fp(tar)n(getlist)f Ft(\(i.e.)17 b(the)c(list)f(of)h(attrib)o(utes)f
(after)g(the)g(ke)o(yword)g Fr(select)p Ft(\).)k(Unfortunately)395
1197 y(only)f(those)g(attrib)o(utes)g(are)g(deli)o(v)o(ered)g(by)g(the)
h(subplan)f(and)h(can)f(therefore)f(be)i(used)g(within)395
1257 y(the)e Fp(having)g(clause)p Ft(.)22 b(T)l(o)15
b(become)f(able)h(to)f(handle)g(queries)h(like)e(that)i(correctly)m(,)f
(we)g(ha)o(v)o(e)h(to)395 1316 y(e)o(xtend)c(the)h(actual)g
Fp(tar)n(getlist)f Ft(by)g(those)h(attrib)o(utes)g(used)g(in)f(the)h
Fr(having)29 b(clause)11 b Ft(b)o(ut)g(not)395 1376 y(already)h
(appearing)f(in)i(the)f Fp(tar)n(getlist)p Ft(.)454 1489
y Fr(List)30 b(*)454 1549 y(check_having_qual_for_vars\(Node)d
(*clause,)1261 1609 y(List)j(*targetlist_so_far\))454
1669 y({)514 1729 y(List)149 b(*t;)514 1848 y(if)30 b(\(IsA\(clause,)e
(Var\)\))514 1908 y({)574 1968 y(Rel)269 b(tmp_rel;)574
2087 y(tmp_rel.targetlist)28 b(=)i(targetlist_so_far;)574
2147 y(/*)g(Check)f(if)h(the)f(VAR)h(is)f(already)g(contained)g(in)h
(the)604 2207 y(*)g(targetlist)604 2267 y(*/)574 2326
y(if)g(\(tlist_member\(\(Var)d(*\)clause,)933 2386 y(\(List)i
(*\)targetlist_so_far\))e(==)j(NULL\))574 2446 y({)634
2506 y(add_tl_element\(&tmp_rel,)d(\(Var)i(*\)clause\);)574
2565 y(})574 2625 y(return)g(tmp_rel.targetlist;)514
2685 y(})514 2745 y(else)574 2804 y(if)h(\(is_funcclause\(clause\))d
(||)j(not_clause\(clause\))693 2864 y(||)g(or_clause\(clause\))e(||)i
(and_clause\(clause\)\))574 2924 y({)634 2984 y(/*)f(This)h(is)f(a)h
(function.)f(Recursively)g(call)g(this)664 3044 y(*)g(routine)g(for)h
(its)g(arguments...)664 3103 y(*/)634 3163 y(foreach\(t,)e(\(\(Expr)i
(*\))f(clause\)->args\))634 3223 y({)693 3283 y(targetlist_so_far)f(=)
753 3342 y(check_having_qual_for_vars\(lfirst)o(\(t\),)1231
3402 y(targetlist_so_far\);)p eop
%%Page: 85 85
85 84 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(85)562
234 y Fr(})562 294 y(return)29 b(targetlist_so_far;)502
354 y(})502 413 y(else)562 473 y(if)g(\(IsA\(clause,)g(Aggreg\)\))562
533 y({)621 593 y(targetlist_so_far)f(=)681 653 y
(check_having_qual_for_vars\()1159 712 y(\(\(Aggreg)h
(*\)clause\)->target,)1159 772 y(targetlist_so_far\);)621
832 y(return)h(targetlist_so_far;)562 892 y(})1159 951
y(.)1159 1011 y(.)1159 1071 y(.)382 1131 y(})198 1271
y Ft(The)13 b(ne)o(xt)f(function)g(is)h(found)e(in)h
Fk(:)c(:)g(:)q Fr(/src/backend/optimizer/plan/)o(planner.c)o
Ft(:)273 1386 y Fo(\017)25 b Fr(union)p 476 1386 15 2
v 17 w(planner\(\))323 1446 y Ft(This)14 b(function)f(creates)h(a)g
Fp(plan)f Ft(from)g(the)h Fp(parsetr)n(ee)g Ft(gi)o(v)o(en)g(to)g(it)f
(by)h(the)g(parameter)f Fr(parse)323 1505 y Ft(that)f(can)g(be)h(e)o(x)
o(ecuted)g(by)f(the)g Fp(e)o(xecutor)p Ft(.)323 1595
y(If)g Fp(aggr)n(e)n(gate)g(functions)g Ft(are)h(present)f(\(indicated)
h(by)f Fr(parse->hasAggs)f Ft(set)j(to)e(true\))g(the)323
1655 y(\002rst)f(step)i(is)g(to)f(e)o(xtend)g(the)g Fp(tar)n(getlist)g
Ft(by)g(those)h(attrib)o(utes)f(that)g(are)g(used)h(within)e(the)h
Fp(having)323 1715 y(clause)h Ft(\(if)e(an)o(y)i(is)h(present\))e(b)o
(ut)g(do)h(not)f(appear)h(in)g(the)f Fp(select)i(list)e
Ft(\(Refer)g(to)h(the)g(description)323 1775 y(of)e Fr(check)p
529 1775 V 18 w(having)p 727 1775 V 17 w(qual)p 864 1775
V 18 w(for)p 972 1775 V 17 w(vars\(\))h Ft(abo)o(v)o(e\).)323
1865 y(The)17 b(ne)o(xt)g(step)g(is)g(to)g(call)f(the)h(function)f
Fr(query)p 1224 1865 V 17 w(planner\(\))g Ft(creating)g(a)h
Fp(plan)g Ft(without)323 1924 y(taking)c(the)g Fp(gr)n(oup)h(clause)p
Ft(,)h(the)e Fp(aggr)n(e)n(gate)g(functions)g Ft(and)h(the)g
Fp(having)f(clause)h Ft(into)f(account)323 1984 y(for)e(the)h(moment.)
323 2074 y(Ne)o(xt)j(insert)h(a)f Fr(GRP)h Ft(node)f(at)h(the)f(top)h
(of)f(the)g Fp(plan)h Ft(according)f(to)g(the)h Fp(gr)n(oup)f(clause)h
Ft(of)f(the)323 2134 y Fp(parsetr)n(ee)e Ft(if)f(an)o(y)g(is)h
(present.)323 2224 y(Add)d(an)h Fr(AGG)g Ft(node)f(to)h(the)g(top)f(of)
h(the)f(current)g Fp(plan)h Ft(if)f Fp(aggr)n(e)n(gate)g(functions)h
Ft(are)f(present)h(and)323 2284 y(if)g(a)i Fp(having)f(clause)h
Ft(is)f(present)h(additionally)e(perform)g(the)h(follo)o(wing)f(steps:)
382 2404 y Fn(\226)25 b Ft(Perform)9 b(v)o(arious)i(transformations)e
(to)i(the)g(representation)f(of)g(the)h Fp(having)f(clause)h
Ft(\(e.g.)432 2463 y(transform)g(it)h(to)h(CNF)l(,)f
Fk(:)c(:)g(:)q Ft(\).)382 2553 y Fn(\226)25 b Ft(Attach)30
b(the)f(transformed)f(representation)h(of)g(the)h Fp(having)f(clause)h
Ft(to)f(the)g(\002eld)432 2613 y Fr(plan.qual)12 b Ft(of)g(the)g(just)g
(created)h Fr(AGG)f Ft(node.)382 2703 y Fn(\226)25 b
Ft(Examine)15 b(the)g(whole)g Fp(having)f(clause)h Ft(and)g(search)g
(for)f Fp(aggr)n(e)n(gate)g(functions)p Ft(.)23 b(This)16
b(is)432 2763 y(done)10 b(using)g(the)g(function)f Fr(check)p
1057 2763 V 17 w(having)p 1254 2763 V 18 w(qual)p 1392
2763 V 17 w(for)p 1499 2763 V 18 w(aggs\(\))g Ft(which)h(appends)432
2823 y(e)o(v)o(ery)i Fp(aggr)n(e)n(gate)g(function)g
Ft(found)f(to)h(a)h(list)f(that)h(is)f(\002nally)g(returned.)382
2913 y Fn(\226)25 b Ft(Append)12 b(the)h(list)f(just)h(created)f(to)g
(the)g(list)h(already)f(attached)g(to)h(the)f(\002eld)g
Fr(aggs)g Ft(of)g(the)432 2972 y Fr(AGG)g Ft(node)h(\(this)f(list)g
(contains)g(the)h Fp(aggr)n(e)n(gate)e(functions)h Ft(found)g(in)g(the)
h Fp(tar)n(getlist)p Ft(\).)382 3062 y Fn(\226)25 b Ft(Make)10
b(sure)h(that)f Fp(aggr)n(e)n(gate)f(functions)h Ft(do)h(appear)f(in)g
(the)g Fp(having)g(clause)p Ft(.)16 b(This)11 b(is)f(done)432
3122 y(by)15 b(comparing)f(the)g(length)g(of)h(the)f(list)h(attached)g
(to)f Fr(aggs)h Ft(before)f(and)g(after)g(the)h(call)432
3182 y(to)h Fr(check)p 640 3182 V 17 w(having)p 837 3182
V 18 w(qual)p 975 3182 V 17 w(for)p 1082 3182 V 18 w(aggs\(\))p
Ft(.)26 b(If)15 b(the)h(length)g(has)h(not)e(changed,)j(we)432
3242 y(kno)o(w)e(that)h(no)g Fp(aggr)n(e)n(gate)f(function)g
Ft(has)h(been)g(detected)g(and)g(that)f(this)h(query)f(could)432
3302 y(ha)o(v)o(e)d(been)g(formulated)f(using)g(only)h(a)g
Fp(wher)n(e)h(clause)p Ft(.)j(In)12 b(this)h(case)h(an)f(error)e
(message)432 3361 y(is)i(printed)e(to)i(the)f(screen)h(and)f(the)g
(processing)h(is)f(aborted.)p eop
%%Page: 86 86
86 85 bop 270 60 a Ft(86)85 b Fm(CHAPTER)14 b(3.)25 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)454
234 y Fr(Plan)30 b(*)454 294 y(union_planner\(Query)e(*parse\))454
354 y({)544 413 y(List)209 b(*tlist)29 b(=)h(parse->targetList;)395
533 y(+)119 b(/*)30 b(copy)f(the)h(original)f(tlist,)g(we)g(will)h
(need)f(the)395 593 y(+)149 b(*)30 b(original)f(one)g(for)h(the)f(AGG)h
(node)f(later)h(on)f(*/)395 653 y(+)149 b(List)29 b(*new_tlist)g(=)h
(new_unsorted_tlist\(tlist\);)1231 712 y(.)1231 772 y(.)1231
832 y(.)395 892 y(+)268 b(if)30 b(\(parse->hasAggs\))395
951 y(+)268 b({)395 1011 y(+)328 b(/*)30 b(extend)f(targetlist)g(by)g
(variables)g(not)395 1071 y(+)358 b(*)30 b(contained)f(already)g(but)g
(used)h(in)f(the)395 1131 y(+)358 b(*)30 b(havingQual.)395
1191 y(+)358 b(*/)395 1250 y(+)328 b(if)30 b(\(parse->havingQual)e(!=)h
(NULL\))395 1310 y(+)388 b({)395 1370 y(+)448 b(new_tlist)29
b(=)395 1430 y(+)508 b(check_having_qual_for_vars\()395
1489 y(+)896 b(parse->havingQual,)395 1549 y(+)g(new_tlist\);)395
1609 y(+)388 b(})395 1669 y(+)268 b(})1231 1729 y(.)1231
1788 y(.)1231 1848 y(.)693 1908 y(/*)30 b(Call)g(the)f(planner)g(for)h
(everything)723 1968 y(*)g(but)g(groupclauses)e(and)i(aggregate)f
(funcs.)723 2027 y(*/)693 2087 y(result_plan)g(=)h
(query_planner\(parse,)1411 2147 y(parse->commandType,)1411
2207 y(new_tlist,)1411 2267 y(\(List)f(*\))h(parse->qual\);)1231
2326 y(.)1231 2386 y(.)1231 2446 y(.)634 2506 y(/*)f(If)h(aggregate)f
(is)h(present,)e(insert)i(the)f(AGG)h(node)664 2565 y(*/)634
2625 y(if)f(\(parse->hasAggs\))634 2685 y({)693 2745
y(int)h(old_length=0,)e(new_length=0;)693 2804 y(/*)i(Create)f(the)h
(AGG)f(node)h(but)f(use)h('tlist')f(not)723 2864 y(*)h('new_tlist')f
(as)g(target)h(list)f(because)g(we)723 2924 y(*)h(don't)f(want)h(the)f
(additional)g(attributes)723 2984 y(*)h(\(only)f(used)h(for)f(the)h
(havingQual,)f(see)723 3044 y(*)h(above\))f(to)h(show)f(up)h(in)g(the)f
(result.)723 3103 y(*/)693 3163 y(result_plan)g(=)h(\(Plan)f(*\))h
(make_agg\(tlist,)1560 3223 y(result_plan\);)1231 3283
y(.)1231 3342 y(.)1231 3402 y(.)p eop
%%Page: 87 87
87 86 bop 198 60 a Fm(3.7.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(THE)h(HA)-7 b(VING)12 b(CLA)m(USE)622 b Ft(87)323
234 y Fr(+)268 b(/*)30 b(Check)f(every)h(clause)f(of)h(the)f
(havingQual)g(for)323 294 y(+)298 b(*)30 b(aggregates)f(used)g(and)h
(append)f(them)g(to)323 354 y(+)298 b(*)30 b(the)g(list)f(in)h
(result_plan->aggs)323 413 y(+)298 b(*/)323 473 y(+)268
b(foreach\(clause,)323 533 y(+)508 b(\(\(Agg)29 b(*\))h
(result_plan\)->plan.qual\))323 593 y(+)268 b({)323 653
y(+)328 b(/*)30 b(Make)f(sure)h(there)f(are)h(aggregates)e(in)i(the)323
712 y(+)358 b(*)30 b(havingQual)f(if)g(so,)h(the)f(list)h(must)f(be)323
772 y(+)358 b(*)30 b(longer)f(after)g(check_having_qual_for_aggs)323
832 y(+)358 b(*/)323 892 y(+)328 b(old_length)29 b(=)323
951 y(+)388 b(length\(\(\(Agg)29 b(*\))g(result_plan\)->aggs\);)323
1011 y(+)323 1071 y(+)328 b(\(\(Agg)30 b(*\))f(result_plan\)->aggs)f(=)
323 1131 y(+)418 b(nconc\(\(\(Agg)29 b(*\))g(result_plan\)->aggs,)323
1191 y(+)597 b(check_having_qual_for_aggs\()323 1250
y(+)657 b(\(Node)29 b(*\))h(lfirst\(clause\),)323 1310
y(+)657 b(\(\(Agg)29 b(*\)result_plan\)->)323 1370 y(+)777
b(plan.lefttree->targetlist,)323 1430 y(+)657 b(\(\(List)29
b(*\))h(parse->groupClause\)\)\);)323 1489 y(+)328 b(/*)30
b(Have)f(a)h(look)g(at)f(the)h(length)f(of)h(the)f(returned)323
1549 y(+)358 b(*)30 b(list.)f(If)h(there)f(is)h(no)f(difference,)g(no)
323 1609 y(+)358 b(*)30 b(aggregates)f(have)g(been)g(found)h(and)f
(that)h(means)323 1669 y(+)358 b(*)30 b(that)f(the)h(Qual)f(belongs)g
(to)h(the)g(where)f(clause)323 1729 y(+)358 b(*/)323
1788 y(+)328 b(if)30 b(\(\(\(new_length)e(=)323 1848
y(+)508 b(length\(\(\(Agg)28 b(*\))i(result_plan\)->aggs\)\)==)323
1908 y(+)508 b(old_length\))28 b(||)i(\(new_length)e(==)i(0\)\))323
1968 y(+)328 b({)323 2027 y(+)388 b(elog\(ERROR,"This)28
b(could)h(have)h(been)f(done)h(in)f(a)323 2087 y(+)1135
b(where)29 b(clause!!"\);)323 2147 y(+)388 b(return)29
b(\(Plan)h(*\)NIL;)323 2207 y(+)328 b(})323 2267 y(+)268
b(})1159 2326 y(.)1159 2386 y(.)1159 2446 y(.)382 2506
y(})198 2647 y Fn(Executor)198 2743 y Ft(The)17 b Fp(e)o(xecutor)g
Ft(takes)g(the)f Fp(queryplan)h Ft(produced)f(by)g(the)h
Fp(planner/optimizer)g Ft(in)f(the)h(way)f(just)g(de-)198
2803 y(scribed)c(and)g(processes)h(all)e Fp(aggr)n(e)n(gate)g
(functions)h Ft(in)g(the)g(way)f(described)h(in)g(section)g(3.7.1)g
Fp(The)g(Im-)198 2863 y(plementation)g(of)g(Aggr)n(e)n(gate)g
(Functions)h Ft(b)o(ut)f(before)g(the)g(tuple)g(deri)o(v)o(ed)g(is)h
(handed)f(back)h(the)f Fp(oper)o(-)198 2922 y(ator)h(tr)n(ee)g
Ft(attached)f(to)g(the)h(\002eld)f Fr(qpqual)g Ft(is)g(e)o(v)o(aluated)
g(by)h(calling)f(the)g(function)g Fr(ExecQual\(\))p Ft(.)198
2982 y(This)i(function)e(recursi)o(v)o(ely)g(steps)i(through)e(the)h
Fp(oper)o(ator)h(tr)n(ee)f Ft(\(i.e.)18 b(the)13 b Fp(having)g(clause)p
Ft(\))g(and)g(e)o(v)o(al-)198 3042 y(uates)k(the)g(predicates)f
(appearing)g(there.)29 b(Thanks)17 b(to)g(our)f(changes)h(that)f(ha)o
(v)o(e)h(been)g(made)g(to)f(the)198 3102 y Fp(planner)i
Ft(the)g(v)o(alues)f(of)h(all)g(operands)f(needed)h(to)g(e)o(v)o
(aluate)f(the)h(predicates)g(\(e.g.)32 b(the)18 b(v)o(alues)g(of)198
3162 y(all)13 b Fp(aggr)n(e)n(gate)f(functions)p Ft(\))g(are)h(already)
f(present)h(and)g(can)g(be)g(accessed)i(throughout)c(the)i(e)o(v)o
(aluation)198 3221 y(without)f(an)o(y)g(problems.)273
3283 y(If)i(the)h(e)o(v)o(aluation)e(of)i(the)f Fp(having)h
(quali\002cation)f Ft(returns)g Fr(true)g Ft(the)h(tuple)g(is)g
(returned)e(by)i(the)198 3342 y(function)c Fr(execAgg\(\))h
Ft(otherwise)g(it)g(is)h(ignored)f(and)g(the)g(ne)o(xt)h(group)e(is)i
(processed.)p eop
%%Page: 88 88
88 87 bop 270 60 a Ft(88)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(The)26 b(necessary)h(changes)f(and)g(enhancements)g(ha)o(v)o
(e)g(been)g(applied)f(to)h(the)g(follo)o(wing)e(func-)270
294 y(tion)12 b(in)g(the)g(\002le)h Fk(:)8 b(:)g(:)p
Fr(/src/backend/executor/nodeAgg)o(.c)p Ft(:)345 391
y Fo(\017)25 b Fr(execAgg\(\))17 b Ft(Whene)o(v)o(er)g(the)h
Fp(e)o(xecutor)h Ft(gets)f(to)g(an)g Fr(AGG)g Ft(node)g(this)g
(function)f(is)i(called.)395 451 y(Before)d(the)g Fp(having)g(logic)g
Ft(had)g(been)h(implemented,)g(all)g(the)f Fp(tuples)h
Ft(of)f(the)g(current)g(group)395 511 y(were)j(fetched)f(from)g(the)h
Fp(subplan)g Ft(and)h(all)f Fp(aggr)n(e)n(gate)f(functions)h
Ft(were)g(applied)g(to)g(these)395 571 y(tuples.)c(After)d(that,)h(the)
f(results)g(were)h(handed)f(back)h(to)f(the)g(calling)g(function.)395
650 y(Since)i(the)g Fp(having)h(logic)f Ft(has)h(been)f(implemented)g
(there)h(is)f(one)h(additional)f(step)h(e)o(x)o(ecuted.)395
710 y(Before)d(the)h(results)g(of)f(applying)g(the)h
Fp(aggr)n(e)n(gate)f(functions)g Ft(are)h(handed)g(back,)g(the)g
(function)395 769 y Fr(ExecQual\(\))d Ft(is)i(called)f(with)h(the)f
(representation)g(of)g(the)g Fp(having)h(clause)g Ft(as)g(an)f(ar)o
(gument.)395 829 y(If)h Fr(true)h Ft(is)h(returned,)f(the)g(results)g
(are)g(handed)h(back,)g(otherwise)f(the)o(y)g(are)g(ignored)g(and)g(we)
395 889 y(start)18 b(from)f(the)i(be)o(ginning)f(for)f(the)i(ne)o(xt)f
(group)g(until)g(a)g(group)g(meeting)g(the)h(restrictions)395
949 y(gi)o(v)o(en)12 b(in)g(the)g Fp(having)g(clause)h
Ft(is)g(found.)454 1066 y Fr(TupleTableSlot)29 b(*)454
1125 y(ExecAgg\(Agg)g(*node\))454 1185 y({)1231 1245
y(.)1231 1305 y(.)1231 1364 y(.)634 1424 y(/*)g(We)h(loop)f(retrieving)
g(groups)g(until)h(we)f(find)h(one)664 1484 y(*)f(matching)g
(node->plan.qual)664 1544 y(*/)395 1603 y(+)209 b(do)395
1663 y(+)g({)1231 1723 y(.)1231 1783 y(.)1231 1843 y(.)693
1902 y(/*)30 b(Apply)f(*all*)h(aggregate)f(function)g(to)g(the)723
1962 y(*)h(tuples)f(of)h(the)g(*current*)e(group)723
2022 y(*/)1231 2082 y(.)1231 2141 y(.)1231 2201 y(.)693
2261 y(econtext->ecxt_scantuple)g(=)962 2321 y
(aggstate->csstate.css_ScanTupleSlot)o(;)693 2381 y(resultSlot)h(=)h
(ExecProject\(projInfo,)d(&isDone\);)395 2500 y(+)268
b(/*)30 b(As)g(long)f(as)h(the)f(retrieved)g(group)h(does)f(not)395
2560 y(+)298 b(*)30 b(match)f(the)h(qualifications)e(it)i(is)g(ignored)
f(and)395 2620 y(+)298 b(*)30 b(the)g(next)f(group)g(is)h(fetched)395
2679 y(+)298 b(*/)395 2739 y(+)268 b(if\(node->plan.qual)28
b(!=)i(NULL\))395 2799 y(+)268 b({)395 2859 y(+)328 b(qual_result)29
b(=)395 2919 y(+)448 b(ExecQual\(fix_opids\(node->plan)o(.qual\),)395
2978 y(+)717 b(econtext\);)395 3038 y(+)268 b(})395 3098
y(+)g(if)30 b(\(oneTuple\))f(pfree\(oneTuple\);)395 3158
y(+)209 b(})395 3217 y(+)g(while\(\(node->plan.qual!=NULL)o(\))27
b(&&)395 3277 y(+)926 b(\(qual_result!=true\)\);)634
3337 y(return)29 b(resultSlot;)454 3397 y(})p eop
%%Page: 89 89
89 88 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)349 b Ft(89)198
234 y Fi(3.8)71 b(The)18 b(Realization)f(of)g(Union,)g(Intersect)g(and)
h(Except)198 352 y Ft(SQL92)12 b(supports)g(the)h(well)f(kno)o(wn)g
(set)g(theoretic)g(operations)g Fp(union)p Ft(,)g Fp(intersect)h
Ft(and)f Fp(set)h(dif)o(fer)n(ence)198 411 y Ft(\(the)j
Fp(set)h(dif)o(fer)n(ence)f Ft(is)h(called)f Fp(e)o(xcept)h
Ft(in)f(SQL92\).)27 b(The)17 b(operators)f(are)g(used)h(to)f(connect)g
(two)g(or)198 471 y(more)c Fr(select)g Ft(statements.)18
b(Ev)o(ery)13 b Fr(select)f Ft(statement)h(returns)f(a)h(set)g(of)f
(tuples)h(and)g(the)g(opera-)198 531 y(tors)f(between)h(the)f
Fr(select)g Ft(statements)g(tell)h(ho)o(w)f(to)g(mer)o(ge)g(the)g
(returned)g(sets)h(of)f(tuples)g(into)g(one)198 591 y(result)g
(relation.)198 729 y Fn(Example)h(3.4)25 b Ft(Let)13
b(the)f(follo)o(wing)f(tables)i(be)f(gi)o(v)o(en:)616
842 y Fr(A)60 b(C1|C2|C3)268 b(B)60 b(C1|C2|C3)706 902
y(--+--+--)358 b(--+--+--)736 961 y(1|)30 b(a|)f(b)389
b(1|)29 b(a|)h(b)736 1021 y(2|)g(a|)f(b)389 b(5|)29 b(a|)h(b)736
1081 y(3|)g(c|)f(d)389 b(3|)29 b(c|)h(d)736 1141 y(4|)g(e|)f(f)389
b(8|)29 b(e|)h(f)945 1260 y(C)60 b(C1|C2|C3)1035 1320
y(--+--+--)1065 1380 y(4|)29 b(e|)h(f)1065 1440 y(8|)f(e|)h(f)198
1549 y Ft(No)o(w)12 b(let')m(s)h(ha)o(v)o(e)f(a)h(look)f(at)g(the)h
(results)f(of)g(the)g(follo)o(wing)f(queries:)258 1661
y Fr(select)29 b(*)h(from)f(A)258 1721 y(union)258 1781
y(select)g(*)h(from)f(B;)198 1890 y Ft(deri)o(v)o(es)12
b(the)h(set)f(theoretic)g Fp(union)g Ft(of)g(the)g(two)g(tables:)1035
2002 y Fr(C1|C2|C3)1035 2062 y(--+--+--)1065 2122 y(1|)29
b(a|)h(b)1065 2182 y(2|)f(a|)h(b)1065 2242 y(3|)f(c|)h(d)1065
2301 y(4|)f(e|)h(f)1065 2361 y(5|)f(a|)h(b)1065 2421
y(8|)f(e|)h(f)198 2530 y Ft(The)13 b Fr(select)f Ft(statements)g(used)h
(may)f(be)h(more)f(comple)o(x:)258 2643 y Fr(select)29
b(C1,)h(C3)f(from)h(A)318 2702 y(where)f(C2)h(=)f('a')258
2762 y(union)258 2822 y(select)g(C1,)h(C2)f(from)h(B)318
2882 y(where)f(C3)h(=)f('b';)198 2991 y Ft(will)12 b(return)f(the)i
(follo)o(wing)e(table:)1065 3103 y Fr(C1|C3)1065 3163
y(--+--)1095 3223 y(1|)29 b(b)1095 3283 y(2|)g(b)1095
3342 y(1|)g(a)1095 3402 y(5|)g(a)p eop
%%Page: 90 90
90 89 bop 270 60 a Ft(90)85 b Fm(CHAPTER)14 b(3.)25 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(Note)j(that)f(the)h(selected)g(columns)f(do)h(not)f(need)h(to)
g(ha)o(v)o(e)g(identical)f(names,)i(the)o(y)f(only)f(ha)o(v)o(e)h(to)g
(be)270 294 y(of)e(the)g(same)h(type.)k(In)13 b(the)g(pre)o(vious)g(e)o
(xample)g(we)h(selected)g(for)e Fr(C1)h Ft(and)g Fr(C3)g
Ft(in)h(the)f(\002rst)g Fr(select)270 354 y Ft(statement)i(and)h(for)e
Fr(C1)h Ft(and)g Fr(C2)g Ft(in)h(the)f(second)g(one.)25
b(The)16 b(names)f(of)g(the)g(resulting)g(columns)g(are)270
413 y(taken)d(from)f(the)h(\002rst)g Fr(select)g Ft(statement.)270
533 y(Let')m(s)h(ha)o(v)o(e)g(a)f(look)g(at)h(a)f(query)g(using)h
Fr(intersect)p Ft(:)330 634 y Fr(select)29 b(*)h(from)f(A)330
694 y(intersect)330 754 y(select)g(*)h(from)f(B;)270
855 y Ft(will)12 b(return:)1107 956 y Fr(C1|C2|C3)1107
1016 y(--+--+--)1137 1076 y(1|)29 b(a|)h(b)1137 1136
y(3|)f(c|)h(d)270 1236 y Ft(Here)12 b(is)h(an)f(e)o(xample)h(using)f
Fr(except)p Ft(:)330 1338 y Fr(select)29 b(*)h(from)f(A)330
1398 y(except)330 1457 y(select)g(*)h(from)f(B;)270 1558
y Ft(will)12 b(return:)1107 1660 y Fr(C1|C2|C3)1107 1719
y(--+--+--)1137 1779 y(2|)29 b(a|)h(b)1137 1839 y(4|)f(e|)h(f)270
1940 y Ft(The)11 b(last)g(e)o(xamples)g(were)f(rather)g(simple)g
(because)h(the)o(y)g(only)f(used)h(one)g(set)g(operator)e(at)i(a)f
(time)g(with)270 2000 y(only)h(two)f(operands.)15 b(No)o(w)c(we)g(look)
g(at)g(some)g(more)f(comple)o(x)h(queries)g(in)n(v)o(olving)f(more)h
Fp(oper)o(ators)p Ft(:)330 2101 y Fr(select)29 b(*)h(from)f(A)330
2161 y(union)330 2221 y(select)g(*)h(from)f(B)330 2280
y(intersect)330 2340 y(select)g(*)h(from)f(C;)270 2441
y Ft(will)12 b(return:)1107 2542 y Fr(C1|C2|C3)1107 2602
y(--+--+--)1137 2662 y(4|)29 b(e|)h(f)1137 2722 y(8|)f(e|)h(f)270
2823 y Ft(The)11 b(abo)o(v)o(e)g(query)f(performs)f(the)i(set)g
(theoretic)f(computation)f Fl(\()p Fk(A)t Fo([)t Fk(B)r
Fl(\))t Fo(\\)t Fk(C)t Ft(.)17 b(When)10 b(no)h(parentheses)270
2882 y(are)j(used,)h(the)f(operations)g(are)g(considered)g(to)g(be)g
(left)f(associati)o(v)o(e,)j(i.e.)21 b Fk(A)13 b Fo([)f
Fk(B)j Fo([)e Fk(C)i Fo([)e Fk(D)i Ft(will)f(be)270 2942
y(treated)e(as)h Fl(\(\()p Fk(A)f Fo([)f Fk(B)r Fl(\))h
Fo([)f Fk(C)t Fl(\))g Fo([)g Fk(D)q Ft(.)270 3062 y(The)i(same)g(query)
f(using)g(parenthesis)h(can)f(lead)h(to)f(a)g(completely)g(dif)o
(ferent)f(result:)330 3163 y Fr(select)29 b(*)h(from)f(A)330
3223 y(union)330 3283 y(\(select)g(*)h(from)f(B)360 3342
y(intersect)360 3402 y(select)g(*)h(from)f(C\);)p eop
%%Page: 91 91
91 90 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)349 b Ft(91)198
234 y(performs)11 b Fk(A)h Fo([)f Fl(\()p Fk(B)j Fo(\\)d
Fk(C)t Fl(\))h Ft(and)g(will)g(return:)1035 333 y Fr(C1|C2|C3)1035
393 y(--+--+--)1065 453 y(1|)29 b(a|)h(b)1065 513 y(2|)f(a|)h(b)1065
572 y(3|)f(c|)h(d)1065 632 y(4|)f(e|)h(f)1065 692 y(8|)f(e|)h(f)198
835 y Fh(3.8.1)59 b(Ho)o(w)15 b(Unions)h(ha)o(v)o(e)e(been)g(Realized)g
(Until)g(V)-6 b(ersion)14 b(6.3.2)198 928 y Ft(First)d(we)h(gi)o(v)o(e)
g(a)g(description)f(of)h(the)f(implementation)g(of)g
Fp(union)h Ft(and)f Fp(union)h(all)f Ft(until)h(v)o(ersion)f(6.3.2)198
988 y(because)g(we)f(need)g(it)g(to)g(understand)g(the)g
(implementation)f(of)g Fp(intersect)h Ft(and)g Fp(e)o(xcept)h
Ft(described)f(later)m(.)198 1107 y(A)i Fp(union)g Ft(query)g(is)h
(passed)g(through)f(the)g(usual)h(stages:)273 1206 y
Fo(\017)25 b Ft(parser)273 1306 y Fo(\017)g Ft(re)o(write)11
b(system)273 1405 y Fo(\017)25 b Ft(planner/optimizer)273
1505 y Fo(\017)g Ft(e)o(x)o(ecutor)198 1604 y(and)11
b(we)g(will)f(no)o(w)g(describe)h(what)g(e)o(v)o(ery)f(single)h(stage)g
(does)g(to)g(the)f(query)m(.)15 b(F)o(or)10 b(our)g(e)o(xplanation)h
(we)198 1664 y(assume)j(to)f(process)g(a)h(simple)f(query)f(\(i.e.)19
b(a)13 b(query)g(without)f Fp(subselects)p Ft(,)j Fp(aggr)n(e)n(gates)e
Ft(and)g(without)198 1724 y(in)n(v)o(olving)e Fp(vie)o(ws)p
Ft(\))198 1856 y Fn(The)h(Parser)i(Stage)198 1949 y Ft(As)f(described)f
(earlier)g(the)g Fp(parser)h(stage)f Ft(can)g(be)h(di)o(vided)e(into)h
(two)g(parts:)273 2049 y Fo(\017)25 b Ft(the)12 b Fp(parser)h
Ft(b)o(uilt)f(up)g(by)g(the)h(grammar)e(rules)h(gi)o(v)o(en)g(in)g
Fr(gram.y)g Ft(and)273 2148 y Fo(\017)25 b Ft(the)12
b Fp(tr)o(ansformation)g(r)n(outines)g Ft(performing)e(a)i(lot)g(of)g
(changes)g(and)g(analysis)h(to)f(the)g(tree)g(b)o(uilt)323
2208 y(up)g(by)g(the)g(parser)m(.)k(Most)d(of)f(these)h(routines)f
(reside)g(in)g Fr(analyze.c)p Ft(.)198 2307 y(A)18 b
Fp(union)f Ft(statement)h(consists)h(of)e(two)h(or)f(more)g
Fp(select)i Ft(statements)f(connected)g(by)g(the)f(ke)o(yword)198
2367 y Fr(union)12 b Ft(as)h(the)f(follo)o(wing)f(e)o(xample)i(sho)o
(ws:)258 2466 y Fr(select)29 b(*)h(from)f(A)318 2526
y(where)g(C1=1)258 2586 y(union)258 2645 y(select)g(*)h(from)f(B)318
2705 y(where)g(C2)h(=)f('a')258 2765 y(union)258 2825
y(select)g(*)h(from)f(C)318 2885 y(where)g(C3)h(=)f('f')198
2984 y Ft(The)17 b(abo)o(v)o(e)f Fp(union)g Ft(statement)g(consists)g
(of)g(three)g Fp(select)g Ft(statements)h(connected)f(by)f(the)h(ke)o
(yword)198 3044 y Fr(union)p Ft(.)i(W)l(e)13 b(will)g(refer)f(to)h(the)
h(\002rst)e Fp(select)i Ft(statement)f(by)g(A,)h(to)f(the)g(second)h
(one)f(by)g(B)h(and)f(to)g(the)198 3103 y(third)i(one)g(by)h(C)g(for)e
(our)h(further)g(e)o(xplanation)g(\(in)g(the)g(ne)o(w)h(notation)f(our)
g(query)g(looks)g(like)g(this:)198 3163 y Fr(A)30 b(union)f(B)h(union)f
(C)p Ft(\).)198 3283 y(The)g Fp(parser)g Ft(\(gi)o(v)o(en)f(by)h
Fr(gram.y)p Ft(\))e(processes)j(all)e(three)h Fr(select)e
Ft(statements,)34 b(creates)29 b(a)198 3342 y Fr(SelectStmt)13
b Ft(node)g(for)g(e)o(v)o(ery)g Fr(select)g Ft(and)h(attaches)g(the)g
Fr(where)f Ft(quali\002cations,)h Fp(tar)n(getlists)198
3402 y Ft(etc.)48 b(to)23 b(the)g(corresponding)g(nodes.)48
b(Then)23 b(it)g(creates)h(a)f(list)g(of)g(the)g(second)h(and)f(the)g
(third)p eop
%%Page: 92 92
92 91 bop 270 60 a Ft(92)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)275
1049 y @beginspecial 127 @llx 309 @lly 485 @urx 482 @ury
3580 @rwi @setspecial
%%BeginDocument: figures/parser_union_back.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
100.0 495.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 450 450 m 1800 450 l gs col-1 s gr 
% Polyline
n 450 225 m 1800 225 l 1800 1350 l 450 1350 l cp gs col-1 s gr 
% Polyline
n 450 1080 m 1800 1080 l gs col-1 s gr 
% Polyline
n 450 810 m 1800 810 l gs col-1 s gr 
% Polyline
n 1530 450 m 1530 1350 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
540 405 m
gs 1 -1 sc (SelectStmt node \(A\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
900 720 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 990 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1260 m
gs 1 -1 sc (unionclause) col-1 sh gr
% Polyline
n 4365 2655 m 4635 2925 l gs col-1 s gr 
% Polyline
n 4635 2655 m 4365 2925 l gs col-1 s gr 
% Polyline
n 3285 2025 m 4635 2025 l gs col-1 s gr 
% Polyline
n 3285 1800 m 4635 1800 l 4635 2925 l 3285 2925 l cp gs col-1 s gr 
% Polyline
n 3285 2655 m 4635 2655 l gs col-1 s gr 
% Polyline
n 3285 2385 m 4635 2385 l gs col-1 s gr 
% Polyline
n 4365 2025 m 4365 2925 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3375 1980 m
gs 1 -1 sc (SelectStmt node \(C\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3735 2295 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 2565 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 2835 m
gs 1 -1 sc (unionclause) col-1 sh gr
% Polyline
gs  clippath
2103 1185 m 2223 1215 l 2103 1245 l 2265 1245 l 2265 1185 l  cp clip
n 1665 1215 m 2250 1215 l gs col-1 s gr gr

% arrowhead
n 2103 1185 m 2223 1215 l 2103 1245 l 2103 1215 l 2103 1185 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3453 1185 m 3573 1215 l 3453 1245 l 3615 1245 l 3615 1185 l  cp clip
n 2655 1215 m 3600 1215 l gs col-1 s gr gr

% arrowhead
n 3453 1185 m 3573 1215 l 3453 1245 l 3453 1215 l 3453 1185 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2250 1080 m 2790 1080 l 2790 1350 l 2250 1350 l cp gs col-1 s gr 
% Polyline
n 3600 1080 m 4140 1080 l 4140 1350 l 3600 1350 l cp gs col-1 s gr 
% Polyline
n 2520 1080 m 2520 1350 l gs col-1 s gr 
% Polyline
n 3870 1080 m 3870 1350 l gs col-1 s gr 
% Polyline
n 3870 1080 m 4140 1350 l gs col-1 s gr 
% Polyline
n 3870 1350 m 4140 1080 l gs col-1 s gr 
% Polyline
gs  clippath
3935 1652 m 3950 1774 l 3879 1674 l 3937 1825 l 3993 1803 l  cp clip
n 3735 1215 m 3960 1800 l gs col-1 s gr gr

% arrowhead
n 3935 1652 m 3950 1774 l 3879 1674 l 3907 1663 l 3935 1652 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1878 2490 m 1998 2520 l 1878 2550 l 2040 2550 l 2040 2490 l  cp clip
n 1665 2520 m 2025 2520 l gs col-1 s gr gr

% arrowhead
n 1878 2490 m 1998 2520 l 1878 2550 l 1878 2520 l 1878 2490 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1530 2655 m 1800 2925 l gs col-1 s gr 
% Polyline
n 1800 2655 m 1530 2925 l gs col-1 s gr 
% Polyline
n 450 2025 m 1800 2025 l gs col-1 s gr 
% Polyline
n 450 1800 m 1800 1800 l 1800 2925 l 450 2925 l cp gs col-1 s gr 
% Polyline
n 450 2655 m 1800 2655 l gs col-1 s gr 
% Polyline
n 450 2385 m 1800 2385 l gs col-1 s gr 
% Polyline
n 1530 2025 m 1530 2925 l gs col-1 s gr 
% Polyline
gs  clippath
4713 2490 m 4833 2520 l 4713 2550 l 4875 2550 l 4875 2490 l  cp clip
n 4500 2520 m 4860 2520 l gs col-1 s gr gr

% arrowhead
n 4713 2490 m 4833 2520 l 4713 2550 l 4713 2520 l 4713 2490 l  cp gs 0.00 setgray ef gr  col-1 s
% Interp Spline
gs  clippath
2114 874 m 2228 826 l 2150 922 l 2280 825 l 2244 777 l  cp clip
n 1665 945 m
	1820.9 950.7 1888.4 950.7 1935 945 curveto
	1977.7 939.7 2075.0 917.7 2115 900 curveto
	2141.2 888.4 2175.0 865.9 2250 810 curveto
 gs col-1 s gr
 gr

% arrowhead
n 2114 874 m 2228 826 l 2150 922 l 2132 898 l 2114 874 l  cp gs 0.00 setgray ef gr  col-1 s
% Interp Spline
gs  clippath
1259 1733 m 1146 1783 l 1222 1686 l 1095 1786 l 1132 1833 l  cp clip
n 2385 1215 m
	2315.4 1408.3 2270.4 1487.0 2205 1530 curveto
	2009.1 1658.7 1581.4 1552.1 1395 1620 curveto
	1339.3 1640.3 1271.8 1685.3 1125 1800 curveto
 gs col-1 s gr
 gr

% arrowhead
n 1259 1733 m 1146 1783 l 1222 1686 l 1241 1709 l 1259 1733 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
2340 720 m
gs 1 -1 sc (Pointer to qualtree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 915 m
gs 1 -1 sc (of 1st Select) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2070 2475 m
gs 1 -1 sc (Pointer to qualtree) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2070 2670 m
gs 1 -1 sc (of 2nd Select) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1980 m
gs 1 -1 sc (SelectStmt node \(B\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
900 2295 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2565 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2835 m
gs 1 -1 sc (unionclause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4905 2670 m
gs 1 -1 sc (of 3rd Select) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4905 2475 m
gs 1 -1 sc (Pointer to qualtree) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 642 1159 a Ft(Figure)g(3.9:)j(Data)e(structure)f(handed)g
(back)g(by)h(the)f Fp(parser)270 1401 y Fr(SelectStmt)j
Ft(node)g(\(of)g(B)h(and)f(C\))g(and)h(attaches)g(it)f(to)h(the)f
(\002eld)g Fr(unionClause)g Ft(of)g(the)g(\002rst)270
1460 y(node)i(\(of)e(A\).)i(Finally)f(it)h(hands)g(back)f(the)h
(\002rst)f(node)h(\(node)f(A\))g(with)h(the)f(list)h(of)f(the)h
(remaining)270 1520 y(nodes)c(attached)f(as)h(sho)o(wn)f(in)h(\002gure)
e(3.9.)270 1640 y(The)24 b(follo)o(wing)d Fp(tr)o(ansformation)j(r)n
(outines)f Ft(process)g(the)g(data)g(structure)g(handed)g(back)g(by)g
(the)270 1700 y Fp(parser)p Ft(.)45 b(First)21 b(the)h(top)g(node)g
(\(node)f(A\))h(is)g(transformed)f(from)f(a)i Fr(SelectStmt)f
Ft(node)h(to)g(a)270 1759 y Fr(Query)15 b Ft(node.)26
b(The)16 b Fp(tar)n(getlist)p Ft(,)h(the)f Fr(where)f
Ft(quali\002cation)g(etc.)26 b(attached)16 b(to)f(it)h(are)f
(transformed)270 1819 y(as)h(well.)26 b(Ne)o(xt)16 b(the)g(list)g(of)f
(the)h(remaining)f(nodes)h(\(attached)f(to)h Fr(unionClause)e
Ft(of)i(node)f(A\))h(is)270 1879 y(transformed)c(and)h(in)g(this)g
(step)h(also)f(a)h(check)f(is)h(made)f(if)f(the)h(types)h(and)f
(lengths)g(of)g(the)g Fp(tar)n(getlists)270 1939 y Ft(of)g(the)g(in)n
(v)o(olv)o(ed)g(nodes)h(are)f(equal.)19 b(The)14 b(ne)o(w)f
Fr(Query)g Ft(nodes)g(are)h(no)o(w)e(handed)i(back)f(in)g(the)h(same)
270 1998 y(way)e(as)h(the)g Fr(SelectStmt)e Ft(nodes)i(were)g(before)e
(\(i.e.)17 b(the)12 b Fr(Query)h Ft(nodes)f(B)h(and)g(C)g(are)f
(collected)270 2058 y(in)g(a)h(list)f(which)g(is)h(attached)f(to)h
Fr(unionClause)e Ft(of)h Fr(Query)g Ft(node)g(A\).)270
2278 y Fn(The)g(Rewrite)h(System)270 2401 y Ft(If)18
b(an)o(y)g Fp(r)n(e)o(write)i(rules)f Ft(are)f(present)g(for)f(the)i
Fr(Query)e Ft(nodes)i(\(i.e.)34 b(one)18 b(of)g(the)g
Fp(select)h Ft(statements)270 2461 y(uses)d(a)g Fp(vie)o(w)p
Ft(\))f(the)g(necessary)i(changes)e(to)g(the)h Fr(Query)f
Ft(nodes)g(are)g(performed)f(\(see)i(section)f(3.4.1)270
2521 y Fp(T)-5 b(ec)o(hniques)11 b(T)-5 b(o)11 b(Implement)e(V)l(ie)o
(ws)p Ft(\).)17 b(Otherwise)10 b(no)g(changes)h(are)g(made)f(to)g(the)h
(nodes)f(in)h(this)f(stage.)270 2741 y Fn(Planner/Optimizer)270
2864 y Ft(This)15 b(stage)g(has)g(to)f(create)g(a)h Fp(plan)f
Ft(out)g(of)g(the)g Fp(querytr)n(ee)i Ft(produced)d(by)i(the)f
Fp(parser)h(stage)f Ft(that)g(can)270 2924 y(be)j(e)o(x)o(ecuted)g(by)f
(the)g Fp(e)o(xecutor)p Ft(.)29 b(In)16 b(most)g(cases)i(there)e(are)g
(se)o(v)o(eral)h(ways)f(\(paths\))g(with)g(dif)o(ferent)270
2984 y(cost)d(to)f(get)h(to)f(the)h(same)g(result.)j(It')m(s)c(the)g
Fp(planner/optimizer')n(s)h Ft(task)g(to)f(\002nd)g(out)h(which)f(path)
g(is)h(the)270 3044 y(cheapest)f(and)f(to)g(create)h(a)f
Fp(plan)g Ft(using)h(this)f(path.)k(The)d(implementation)e(of)h
Fp(unions)g Ft(in)g(PostgreSQL)270 3103 y(is)i(based)g(on)f(the)g
(follo)o(wing)f(idea:)270 3223 y(The)26 b(set)g(deri)o(v)o(ed)e(by)h(e)
o(v)o(aluating)g Fk(A)c Fo([)g Fk(B)27 b Ft(must)f(contain)f(e)o(v)o
(ery)g(member)f(of)h Fk(A)h Fn(and)e Ft(e)o(v)o(ery)270
3283 y(member)16 b(of)h Fk(B)r Ft(.)30 b(So)17 b(if)f(we)h(append)g
(the)g(members)g(of)f Fk(B)k Ft(to)c(the)h(members)g(of)g
Fk(A)g Ft(we)g(are)g(almost)270 3342 y(done.)f(If)11
b(there)h(e)o(xist)h(members)f(common)f(to)h Fk(A)h Ft(and)f
Fk(B)j Ft(these)d(members)g(are)g(no)o(w)g(contained)g(twice)270
3402 y(in)g(our)g(ne)o(w)g(set,)i(so)e(the)h(only)f(thing)f(left)h(to)h
(do)f(is)g(to)h(remo)o(v)o(e)f(these)h(duplicates.)p
eop
%%Page: 93 93
93 92 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)349 b Ft(93)198
234 y(In)11 b(the)h(case)h(of)e(our)h(e)o(xample)g(the)g
Fp(planner)g Ft(would)f(b)o(uild)g(up)h(the)g Fp(tr)n(ee)g
Ft(sho)o(wn)g(in)g(\002gure)f(3.10.)16 b(Ev)o(ery)198
294 y Fr(Query)f Ft(node)h(is)g(planned)f(separately)h(and)f(results)h
(in)f(a)h Fr(SeqScan)f Ft(node)g(in)h(our)f(e)o(xample.)26
b(The)198 354 y(three)12 b Fr(SeqScan)f Ft(nodes)h(are)g(put)f
(together)h(into)f(a)h(list)g(which)g(is)g(attached)g(to)g
Fr(unionplans)f Ft(of)g(an)198 413 y Fr(Append)h Ft(node.)283
1835 y @beginspecial 143 @llx 261 @lly 469 @urx 530 @ury
3260 @rwi @setspecial
%%BeginDocument: figures/union_plan.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
130.0 543.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 225 450 m 1575 450 l gs col-1 s gr 
% Polyline
n 1305 450 m 1305 1080 l gs col-1 s gr 
% Polyline
n 225 225 m 1575 225 l 1575 1080 l 225 1080 l cp gs col-1 s gr 
% Polyline
n 225 810 m 1575 810 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
675 720 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 405 m
gs 1 -1 sc (Unique node) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 990 m
gs 1 -1 sc (lefttree) col-1 sh gr
% Polyline
n 225 4095 m 1575 4095 l gs col-1 s gr 
% Polyline
n 1305 4095 m 1305 4455 l gs col-1 s gr 
% Polyline
n 225 3870 m 1575 3870 l 1575 4455 l 225 4455 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
675 4365 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 4050 m
gs 1 -1 sc (SeqScan node \(A\)) col-1 sh gr
% Polyline
n 2115 4095 m 3465 4095 l gs col-1 s gr 
% Polyline
n 3195 4095 m 3195 4455 l gs col-1 s gr 
% Polyline
n 2115 3870 m 3465 3870 l 3465 4455 l 2115 4455 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2565 4365 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2205 4050 m
gs 1 -1 sc (SeqScan node \(B\)) col-1 sh gr
% Polyline
n 4005 4095 m 5355 4095 l gs col-1 s gr 
% Polyline
n 5085 4095 m 5085 4455 l gs col-1 s gr 
% Polyline
n 4005 3870 m 5355 3870 l 5355 4455 l 4005 4455 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4455 4365 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4095 4050 m
gs 1 -1 sc (SeqScan node \(C\)) col-1 sh gr
% Polyline
n 765 3285 m 1305 3285 l 1305 3555 l 765 3555 l cp gs col-1 s gr 
% Polyline
n 1035 3285 m 1035 3555 l gs col-1 s gr 
% Polyline
n 2655 3285 m 3195 3285 l 3195 3555 l 2655 3555 l cp gs col-1 s gr 
% Polyline
n 2925 3285 m 2925 3555 l gs col-1 s gr 
% Polyline
n 4545 3285 m 5085 3285 l 5085 3555 l 4545 3555 l cp gs col-1 s gr 
% Polyline
n 4815 3285 m 4815 3555 l gs col-1 s gr 
% Polyline
n 4815 3285 m 5085 3555 l gs col-1 s gr 
% Polyline
n 4815 3555 m 5085 3285 l gs col-1 s gr 
% Polyline
gs  clippath
930 3723 m 900 3843 l 870 3723 l 870 3885 l 930 3885 l  cp clip
n 900 3870 m 900 3420 l gs col-1 s gr gr

% arrowhead
n 930 3723 m 900 3843 l 870 3723 l 900 3723 l 930 3723 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2820 3723 m 2790 3843 l 2760 3723 l 2760 3885 l 2820 3885 l  cp clip
n 2790 3870 m 2790 3420 l gs col-1 s gr gr

% arrowhead
n 2820 3723 m 2790 3843 l 2760 3723 l 2790 3723 l 2820 3723 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2508 3390 m 2628 3420 l 2508 3450 l 2670 3450 l 2670 3390 l  cp clip
n 1170 3420 m 2655 3420 l gs col-1 s gr gr

% arrowhead
n 2508 3390 m 2628 3420 l 2508 3450 l 2508 3420 l 2508 3390 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4710 3723 m 4680 3843 l 4650 3723 l 4650 3885 l 4710 3885 l  cp clip
n 4680 3870 m 4680 3420 l gs col-1 s gr gr

% arrowhead
n 4710 3723 m 4680 3843 l 4650 3723 l 4680 3723 l 4710 3723 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4398 3390 m 4518 3420 l 4398 3450 l 4560 3450 l 4560 3390 l  cp clip
n 3060 3420 m 4545 3420 l gs col-1 s gr gr

% arrowhead
n 4398 3390 m 4518 3420 l 4398 3450 l 4398 3420 l 4398 3390 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 4005 2250 m 5355 2250 l gs col-1 s gr 
% Polyline
n 5085 2250 m 5085 2880 l gs col-1 s gr 
% Polyline
n 4005 2025 m 5355 2025 l 5355 2880 l 4005 2880 l cp gs col-1 s gr 
% Polyline
n 4005 2610 m 5355 2610 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
4455 2520 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4095 2790 m
gs 1 -1 sc (unionplans) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4095 2205 m
gs 1 -1 sc (Append node) col-1 sh gr
% Polyline
n 2115 1350 m 3465 1350 l gs col-1 s gr 
% Polyline
n 3195 1350 m 3195 1980 l gs col-1 s gr 
% Polyline
n 2115 1125 m 3465 1125 l 3465 1980 l 2115 1980 l cp gs col-1 s gr 
% Polyline
n 2115 1710 m 3465 1710 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2565 1620 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2205 1305 m
gs 1 -1 sc (Sort node) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2205 1890 m
gs 1 -1 sc (lefttree) col-1 sh gr
% Interp Spline
gs  clippath
2702 1004 m 2770 1106 l 2661 1048 l 2781 1157 l 2821 1113 l  cp clip
n 1440 945 m
	1674.5 943.0 1775.8 943.0 1845 945 curveto
	2019.7 950.1 2429.3 923.8 2610 990 curveto
	2649.8 1004.6 2694.8 1038.3 2790 1125 curveto
 gs col-1 s gr
 gr

% arrowhead
n 2702 1004 m 2770 1106 l 2661 1048 l 2682 1026 l 2702 1004 l  cp gs 0.00 setgray ef gr  col-1 s
% Interp Spline
gs  clippath
4592 1904 m 4660 2006 l 4551 1948 l 4671 2057 l 4711 2013 l  cp clip
n 3330 1845 m
	3564.5 1843.0 3665.8 1843.0 3735 1845 curveto
	3909.7 1850.1 4319.3 1823.8 4500 1890 curveto
	4539.8 1904.6 4584.8 1938.3 4680 2025 curveto
 gs col-1 s gr
 gr

% arrowhead
n 4592 1904 m 4660 2006 l 4551 1948 l 4572 1926 l 4592 1904 l  cp gs 0.00 setgray ef gr  col-1 s
% Interp Spline
gs  clippath
617 3396 m 738 3421 l 619 3456 l 781 3449 l 779 3389 l  cp clip
n 5220 2745 m
	5223.4 2874.8 5212.2 2931.0 5175 2970 curveto
	5094.8 3054.1 4900.0 3048.4 4815 3060 curveto
	4423.3 3113.5 3494.7 3099.9 3105 3105 curveto
	2694.9 3110.4 1715.1 3105.0 1305 3105 curveto
	1202.5 3105.0 957.7 3100.3 855 3105 curveto
	741.6 3110.1 477.3 3095.1 360 3150 curveto
	330.0 3164.1 274.4 3195.4 270 3240 curveto
	264.4 3296.9 324.9 3350.2 360 3375 curveto
	400.2 3403.3 497.3 3414.7 540 3420 curveto
	578.9 3424.8 635.1 3424.8 765 3420 curveto
 gs col-1 s gr
 gr

% arrowhead
n 617 3396 m 738 3421 l 619 3456 l 618 3426 l 617 3396 l  cp gs 0.00 setgray ef gr  col-1 s
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 743 1945 a(Figure)g(3.10:)j Fp(Plan)e Ft(for)e(a)i(union)f
(query)198 2225 y Fn(Executor)198 2327 y Ft(The)k Fp(e)o(xecutor)h
Ft(will)e(process)h(all)g(the)f Fr(SeqScan)g Ft(nodes)i(and)e(append)h
(all)g(the)f(deli)o(v)o(ered)g(tuples)h(to)198 2387 y(a)e(single)g
Fp(r)n(esult)h(r)n(elation)p Ft(.)21 b(No)o(w)13 b(it)h(is)g(possible)h
(that)e(duplicate)h(tuples)g(are)g(contained)g(in)f(the)h
Fp(r)n(esult)198 2447 y(r)n(elation)e Ft(which)g(ha)o(v)o(e)g(to)g(be)g
(remo)o(v)o(ed.)j(The)e(remo)o(v)o(al)e(is)i(done)e(by)h(the)g
Fr(Unique)g Ft(node)f(and)h(the)g(sort)198 2506 y(is)h(just)f
(performed)f(to)h(make)g(its)h(work)e(easier)m(.)198
2674 y Fh(3.8.2)59 b(Ho)o(w)15 b(Intersect,)f(Except)g(and)h(Union)g(W)
l(ork)f(T)-5 b(ogether)198 2777 y Ft(The)20 b(last)f(section)g(sho)o
(wed)h(that)f(e)o(v)o(ery)f(stage)i(\()p Fp(parser)f(stage)p
Ft(,)i Fp(planner/optimizer)p Ft(,)g Fp(e)o(xecutor)p
Ft(\))f(of)198 2836 y(PostgreSQL)15 b(has)h(to)g(pro)o(vide)f(features)
h(in)f(order)g(to)h(support)f Fp(union)g Ft(statements.)26
b(F)o(or)15 b(the)h(imple-)198 2896 y(mentation)f(of)h
Fp(intersect)h Ft(and)f Fp(e)o(xcept)g Ft(statements)h(\(and)f
(statements)g(in)n(v)o(olving)f(all)h Fp(set)h(oper)o(ators)p
Ft(\))198 2956 y(we)c(choose)f(a)h(dif)o(ferent)e(approach)h(based)g
(on)h Fp(query)g(r)n(e)o(writing)p Ft(.)198 3076 y(The)26
b(idea)f(is)h(based)g(on)f(the)g(fact)f(that)i Fp(intersect)f
Ft(and)g Fp(e)o(xcept)h Ft(statements)g(are)f(redundant)f(in)198
3135 y(SQL,)15 b(i.e.)21 b(for)14 b(e)o(v)o(ery)g Fp(intersect)g
Ft(or)g Fp(e)o(xcept)g Ft(statement)g(it)g(is)g(possible)h(to)f
(formulate)f(a)h(semantically)198 3195 y(equi)o(v)o(alent)d(statement)i
(without)f(using)g Fp(intersect)g Ft(or)g Fp(e)o(xcept)p
Ft(.)198 3342 y Fn(Example)h(3.5)25 b Ft(This)18 b(e)o(xample)g(sho)o
(ws)h(ho)o(w)e(a)h(query)g(using)f Fp(intersect)h Ft(can)h(be)f
(transformed)e(to)i(a)198 3402 y(semantically)12 b(equi)o(v)o(alent)g
(query)g(without)f(an)i Fp(intersect)p Ft(:)p eop
%%Page: 94 94
94 93 bop 270 60 a Ft(94)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)330
234 y Fr(select)29 b(C1,)h(C3)f(from)h(A)330 294 y(where)f(C1)h(=)g(1)
330 354 y(intersect)330 413 y(select)f(C1,)h(C2)f(from)h(B)330
473 y(where)f(C2)h(=)g('c';)270 564 y Ft(is)13 b(equi)o(v)o(alent)e
(to:)330 656 y Fr(select)29 b(C1,)h(C3)330 715 y(from)f(A)330
775 y(where)g(C1)h(=)g(1)f(and)509 835 y(\(C1,)h(C3\))f(in)h(\(select)f
(C1,)g(C2)898 895 y(from)g(B)898 955 y(where)g(C2)h(=)f('c'\);)270
1046 y Ft(This)13 b(e)o(xample)f(sho)o(ws)h(ho)o(w)f(an)h
Fp(e)o(xcept)f Ft(query)g(can)h(be)f(transformed)f(to)i(an)f
Fp(e)o(xcept)p Ft(-less)h(form:)330 1137 y Fr(select)29
b(C1,)h(C2)f(from)h(A)330 1197 y(where)f(C2)h(=)g('c')330
1257 y(except)330 1316 y(select)f(C1,)h(C3)f(from)h(B)330
1376 y(where)f(C3)h(=)g('f';)270 1467 y Ft(is)13 b(equi)o(v)o(alent)e
(to:)330 1558 y Fr(select)29 b(C1,)h(C2)330 1618 y(from)f(A)330
1678 y(where)g(C2)h(=)g('c')f(and)509 1738 y(\(C1,)h(C2\))f(not)h(in)f
(\(select)g(C1,)h(C3)1017 1798 y(from)g(B)1017 1857 y(where)g(C3)f(=)h
('f'\);)270 1949 y Ft(The)13 b(transformations)e(used)i(in)g(e)o
(xample)f(3.5)h(are)g(always)f(v)o(alid)g(because)h(the)o(y)g(just)f
(implement)g(the)270 2008 y(set)h(theoretic)f(de\002nition)f(of)h
Fp(intersect)g Ft(and)h Fp(e)o(xcept)p Ft(:)270 2122
y Fn(De\002nition)e(3.1)270 2181 y Ft(The)i Fp(intersection)f
Ft(of)g(two)g(sets)h Fk(A)g Ft(and)f Fk(B)j Ft(is)d(de\002ned)h(as:)828
2280 y Fl(\()p Fk(A)f Fo(\\)f Fk(B)r Fl(\))k(:=)e Fo(f)p
Fk(x)h Fo(j)g Fk(x)g Fo(2)g Fk(A)e Fo(^)f Fk(x)k Fo(2)f
Fk(B)r Fo(g)270 2380 y Ft(The)f Fp(intersection)f Ft(of)g
Fk(n)g Ft(sets)i Fk(A)828 2387 y Fg(1)850 2380 y Fk(;)8
b(:)g(:)g(:)h(;)f(A)998 2387 y Ff(n)1038 2380 y Ft(is)13
b(de\002ned)f(as:)918 2453 y Ff(n)903 2468 y Fb(\\)899
2575 y Ff(i)p Fg(=1)971 2516 y Fk(A)1008 2523 y Ff(i)1039
2516 y Fl(:=)i Fo(f)p Fk(x)g Fo(j)1220 2453 y Ff(n)1205
2468 y Fb(^)1200 2575 y Ff(i)p Fg(=1)1273 2516 y Fk(x)h
Fo(2)f Fk(A)1400 2523 y Ff(i)1417 2516 y Fo(g)270 2672
y Fn(De\002nition)d(3.2)270 2732 y Ft(The)i Fp(dif)o(fer)n(ence)g
Ft(of)f(two)f(sets)j Fk(A)e Ft(and)h Fk(B)i Ft(is)d(de\002ned)g(as:)843
2831 y Fl(\()p Fk(A)p Fo(n)p Fk(B)r Fl(\))k(:=)d Fo(f)p
Fk(x)h Fo(j)g Fk(x)g Fo(2)g Fk(A)e Fo(^)f Fk(x)j Fo(62)g
Fk(B)r Fo(g)270 2944 y Fn(De\002nition)d(3.3)270 3004
y Ft(The)i Fp(union)f Ft(of)g(two)f(sets)j Fk(A)e Ft(and)h
Fk(B)i Ft(is)d(de\002ned)g(as:)828 3103 y Fl(\()p Fk(A)g
Fo([)f Fk(B)r Fl(\))k(:=)e Fo(f)p Fk(x)h Fo(j)g Fk(x)g
Fo(2)g Fk(A)e Fo(_)f Fk(x)k Fo(2)f Fk(B)r Fo(g)270 3202
y Ft(The)f Fp(union)f Ft(of)g Fk(n)g Ft(sets)h Fk(A)706
3209 y Fg(1)729 3202 y Fk(;)8 b(:)g(:)g(:)h(;)f(A)877
3209 y Ff(n)917 3202 y Ft(is)k(de\002ned)g(as:)918 3276
y Ff(n)903 3291 y Fb([)899 3397 y Ff(i)p Fg(=1)971 3338
y Fk(A)1008 3345 y Ff(i)1039 3338 y Fl(:=)i Fo(f)p Fk(x)g
Fo(j)1220 3276 y Ff(n)1205 3291 y Fb(_)1200 3397 y Ff(i)p
Fg(=1)1273 3338 y Fk(x)h Fo(2)f Fk(A)1400 3345 y Ff(i)1417
3338 y Fo(g)p eop
%%Page: 95 95
95 94 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)349 b Ft(95)198
234 y Fn(De\002nition)11 b(3.4)25 b Ft(Disjuncti)o(v)o(e)12
b(Normal)g(F)o(orm)f(\(DNF\))198 294 y(Let)k Fk(F)24
b Fl(=)17 b Fk(C)427 301 y Fg(1)461 294 y Fo(_)c Fk(:)8
b(:)g(:)13 b Fo(_)f Fk(C)659 301 y Ff(n)700 294 y Ft(be)j(gi)o(v)o(en)f
(where)g(e)o(v)o(ery)g Fk(C)1180 301 y Ff(i)1210 294
y Ft(is)h(of)f(the)g(form)f Fl(\()p Fk(L)1553 276 y Fg(1)1553
307 y Ff(i)1588 294 y Fo(^)g Fk(:)8 b(:)g(:)k Fo(^)h
Fk(L)1784 272 y Ff(k)1805 277 y Fa(i)1784 308 y Ff(i)1823
294 y Fl(\))i Ft(and)f Fk(L)1977 270 y Ff(j)1977 308
y(i)198 354 y Ft(is)g(a)f(propositional)g(v)o(ariable)f(or)h(the)h(ne)o
(gation)f(of)g(a)g(propositional)g(v)o(ariable.)18 b(No)o(w)13
b(we)g(say)h Fk(F)21 b Ft(is)13 b(in)198 413 y(DNF)l(.)198
549 y Fn(Example)g(3.6)25 b Ft(In)12 b(the)g(follo)o(wing)f(e)o(xample)
h(the)h Fk(L)1106 525 y Ff(j)1106 563 y(i)1139 549 y
Ft(are)f(of)g(the)h(form)e Fk(x)j Fo(2)g Fk(X)j Ft(or)12
b Fo(:)p Fl(\()p Fk(x)j Fo(2)f Fk(X)t Fl(\))p Ft(:)273
609 y Fl(\(\()p Fk(x)h Fo(2)f Fk(A)d Fo(^)h(:)p Fl(\()p
Fk(x)i Fo(2)g Fk(B)r Fl(\))e Fo(^)f Fk(x)k Fo(2)f Fk(C)t
Fl(\))c Fo(_)i Fl(\()p Fk(x)i Fo(2)g Fk(D)f Fo(^)e Fk(x)k
Fo(2)f Fk(E)s Fl(\)\))f Ft(is)f(a)h(formula)e(in)h(DNF)273
669 y Fl(\(\()p Fk(x)j Fo(2)f Fk(A)d Fo(_)h Fk(x)i Fo(2)g
Fk(B)r Fl(\))e Fo(^)f Fl(\()p Fk(x)k Fo(2)f Fk(C)g Fo(_)d(:)p
Fl(\()p Fk(x)k Fo(2)f Fk(D)q Fl(\)\)\))g Ft(is)f(not)f(in)g(DNF)l(.)198
779 y(The)g(transformation)e(of)i(an)o(y)g(formula)e(in)i
(propositional)e(logic)i(into)f(DNF)h(is)g(done)f(by)h(successi)o(v)o
(ely)198 839 y(applying)g(the)g(follo)o(wing)f(rules:)273
959 y Fl(\()p Fk(R)p Fl(1\))25 b Fo(:)p Fl(\()p Fk(F)483
966 y Fg(1)518 959 y Fo(_)11 b Fk(F)594 966 y Fg(2)616
959 y Fl(\))j Fo(\))g Fl(\()p Fo(:)p Fk(F)797 966 y Fg(1)831
959 y Fo(^)d(:)p Fk(F)940 966 y Fg(2)963 959 y Fl(\))273
1018 y(\()p Fk(R)p Fl(2\))25 b Fo(:)p Fl(\()p Fk(F)483
1025 y Fg(1)518 1018 y Fo(^)11 b Fk(F)594 1025 y Fg(2)616
1018 y Fl(\))j Fo(\))g Fl(\()p Fo(:)p Fk(F)797 1025 y
Fg(1)831 1018 y Fo(_)d(:)p Fk(F)940 1025 y Fg(2)963 1018
y Fl(\))273 1078 y(\()p Fk(R)p Fl(3\))25 b Fk(F)431 1085
y Fg(1)465 1078 y Fo(^)11 b Fl(\()p Fk(F)560 1085 y Fg(2)594
1078 y Fo(_)g Fk(F)670 1085 y Fg(3)693 1078 y Fl(\))j
Fo(\))g Fl(\()p Fk(F)841 1085 y Fg(1)874 1078 y Fo(^)e
Fk(F)951 1085 y Fg(2)973 1078 y Fl(\))f Fo(_)h Fl(\()p
Fk(F)1099 1085 y Fg(1)1133 1078 y Fo(^)f Fk(F)1209 1085
y Fg(3)1231 1078 y Fl(\))273 1138 y(\()p Fk(R)p Fl(4\))25
b(\()p Fk(F)450 1145 y Fg(1)484 1138 y Fo(_)12 b Fk(F)561
1145 y Fg(2)583 1138 y Fl(\))f Fo(^)h Fk(F)690 1145 y
Fg(3)726 1138 y Fo(\))i Fl(\()p Fk(F)841 1145 y Fg(1)874
1138 y Fo(^)e Fk(F)951 1145 y Fg(3)973 1138 y Fl(\))f
Fo(_)h Fl(\()p Fk(F)1099 1145 y Fg(2)1133 1138 y Fo(^)f
Fk(F)1209 1145 y Fg(3)1231 1138 y Fl(\))198 1257 y Ft(It)24
b(can)i(be)f(sho)o(wn)f(that)h(the)g(transformation)e(using)i(the)g
(rules)g(\(R1\))f(to)h(\(R4\))f(always)g(termi-)198 1317
y(nates)13 b(after)f(a)g(\002nite)g(number)g(of)g(steps.)198
1465 y Fn(Set)g(Operations)f(as)i(Pr)o(opositional)f(Logic)g(F)o
(ormulas)198 1563 y Ft(Using)j(the)f(de\002nitions)h(from)e(abo)o(v)o
(e)i(we)g(can)g(treat)g(formulas)e(in)n(v)o(olving)h(set)h(theoretic)f
(operations)198 1623 y(as)d(formulas)f(of)h Fp(pr)n(opositional)f
(logic)p Ft(.)k(As)d(we)g(will)f(see)i(later)e(these)h(formulas)f(can)h
(easily)g(be)g(used)g(in)198 1683 y(the)h Fr(where-)g
Ft(and)g Fr(having)g Ft(quali\002cations)g(of)g(the)g
Fr(select)g Ft(statements)h(in)n(v)o(olv)o(ed)f(in)g(the)h(query)m(.)
198 1819 y Fn(Example)g(3.7)25 b Ft(Here)12 b(are)g(some)h(e)o
(xamples:)273 1938 y Fl(\(\()p Fk(A)f Fo([)f Fk(B)r Fl(\))h
Fo(\\)f Fk(C)t Fl(\))j(:=)f Fo(f)p Fk(x)h Fo(j)g Fl(\()p
Fk(x)h Fo(2)f Fk(A)d Fo(_)g Fk(x)k Fo(2)f Fk(B)r Fl(\))d
Fo(^)h Fk(x)i Fo(2)g Fk(C)t Fo(g)273 1998 y Fl(\(\()p
Fk(A)e Fo([)f Fk(B)r Fl(\))h Fo(\\)f Fl(\()p Fk(C)k Fo([)c
Fk(D)q Fl(\)\))k(:=)f Fo(f)p Fk(x)g Fo(j)g Fl(\()p Fk(x)g
Fo(2)g Fk(A)e Fo(_)f Fk(x)j Fo(2)g Fk(B)r Fl(\))e Fo(^)f
Fl(\()p Fk(x)k Fo(2)f Fk(C)g Fo(_)e Fk(x)i Fo(2)g Fk(D)q
Fl(\))p Fo(g)273 2058 y Fl(\(\()p Fk(A)e Fo(\\)f Fk(B)r
Fl(\))p Fo(n)p Fk(C)t Fl(\))j(:=)g Fo(f)p Fk(x)g Fo(j)f
Fl(\()p Fk(x)i Fo(2)f Fk(A)e Fo(^)f Fk(x)j Fo(2)g Fk(B)r
Fl(\))e Fo(^)f Fk(x)k Fo(62)f Fk(C)t Fo(g)273 2117 y
Fl(\()p Fk(A)p Fo(n)p Fl(\()p Fk(B)g Fo([)d Fk(C)t Fl(\)\))j(:=)g
Fo(f)p Fk(x)g Fo(j)f Fk(x)i Fo(2)f Fk(A)d Fo(^)g(:)p
Fl(\()p Fk(x)k Fo(2)f Fk(B)g Fo(_)d Fk(x)j Fo(2)g Fk(C)t
Fl(\))p Fo(g)273 2177 y Fl(\(\(\()p Fk(A)e Fo(\\)g Fk(B)r
Fl(\))f Fo([)h Fl(\()p Fk(C)t Fo(n)p Fk(D)q Fl(\)\))f
Fo(\\)h Fk(E)s Fl(\))i(:=)f Fo(f)p Fl(\(\()p Fk(x)i Fo(2)f
Fk(A)d Fo(^)h Fk(x)i Fo(2)g Fk(B)r Fl(\))e Fo(_)f Fl(\()p
Fk(x)k Fo(2)f Fk(C)g Fo(^)d Fk(x)k Fo(62)f Fk(D)q Fl(\)\))e
Fo(^)f Fk(x)k Fo(2)f Fk(E)s Fo(g)198 2335 y Fh(3.8.3)59
b(Implementing)19 b(Intersect)h(and)g(Except)g(Using)g(the)g(Union)h
(Capabili-)377 2404 y(ties)198 2503 y Ft(W)l(e)14 b(want)g(to)g(be)g
(able)g(to)g(use)h(queries)f(in)n(v)o(olving)f(more)h(than)g(just)g
(one)g(type)g(of)g(set)g(operation)f(\(e.g.)198 2563
y(only)18 b Fp(union)g Ft(or)g(only)g Fp(intersect)p
Ft(\))g(at)g(a)h(time,)h(so)f(we)f(ha)o(v)o(e)h(to)f(look)g(for)g(a)g
(solution)g(that)g(supports)198 2622 y(correct)12 b(handling)h(of)g
(queries)g(like)f(that.)18 b(As)13 b(described)g(abo)o(v)o(e)h(there)e
(is)i(a)f(solution)g(for)f(pure)h Fp(union)198 2682 y
Ft(statements)19 b(implemented)f(already)m(,)i(so)f(we)g(ha)o(v)o(e)g
(to)g(de)o(v)o(elop)f(an)h(approach)f(that)h(makes)f(use)i(of)198
2742 y(these)13 b Fp(union)f Ft(capabilities.)198 2862
y(As)27 b(\002gure)g(3.9)g(illustrates,)k(the)c(operands)g(of)f(a)i
Fp(union)e Ft(operation)g(are)h(just)g Fr(Query)g Ft(nodes)198
2921 y(\(the)14 b(\002rst)h(operand)f(is)h(the)g(top)g(node)f(and)h
(all)g(further)e(operands)i(form)f(a)h(list)g(which)f(is)h(attached)g
(to)198 2981 y(the)h(\002eld)f Fr(unionClause)g Ft(of)g(the)g(top)h
(node\).)25 b(So)15 b(our)h(goal)f(will)g(be)h(to)g(transform)e(e)o(v)o
(ery)i(query)198 3041 y(in)n(v)o(olving)11 b(set)i(operations)f(into)f
(this)i(form.)h(\(Note)e(that)g(the)g(operands)g(to)g(the)g
Fp(union)g Ft(operation)f(may)198 3101 y(be)h(comple)o(x,)h(i.e.)k
Fp(subselects)p Ft(,)c Fp(gr)n(ouping)p Ft(,)g Fp(aggr)n(e)n(gates)f
Ft(etc.)k(are)c(allo)o(wed.\))273 3163 y(The)k(transformation)e(of)i(a)
g(query)f(in)n(v)o(olving)g(set)i(operations)e(in)h(an)o(y)g(order)f
(into)h(a)g(query)f(that)198 3223 y(can)g(be)f(accepted)h(by)g(the)f
Fp(union)g Ft(logic)g(is)h(equi)o(v)o(alent)f(to)g(transforming)f(the)i
Fp(membership)f(formula)198 3283 y Ft(\(see)d(de\002nitions)g(3.1,)h
(3.2)f(and)g(3.3\))g(in)g(propositional)f(logic)g(into)h
Fp(disjunctive)g(normal)g(form)g Ft(\(DNF\).)198 3342
y(The)j(transformation)d(of)i(an)o(y)g(formula)f(in)h(propositional)g
(logic)g(into)f(DNF)h(is)h(always)e(possible)i(in)f(a)198
3402 y(\002nite)f(number)g(of)f(steps.)p eop
%%Page: 96 96
96 95 bop 270 60 a Ft(96)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)270
234 y Ft(The)18 b(adv)o(antage)f(of)g(this)g Fp(tr)o(ansformation)h
(tec)o(hnique)f Ft(is)g(the)h(little)e(impact)h(on)g(the)h(whole)f
(system)270 294 y(and)12 b(the)f(implicit)g(in)n(v)o(ocation)g(of)g
(the)h Fp(planner/optimizer)p Ft(.)k(The)c(only)f(changes)h(necessary)h
(are)e(made)270 354 y(to)h(the)h Fp(parser)g(stage)e
Ft(and)i(the)f Fp(r)n(e)o(write)i(system)p Ft(.)270 473
y(Here)24 b(are)f(some)h(changes)g(that)g(had)f(to)h(be)g(applied)f(to)
h(the)f(source)h(code)g(before)f(the)g Fp(parser)270
533 y(stage)12 b Ft(and)g(the)g Fp(r)n(e)o(write)i(system)f
Ft(could)f(be)h(adapted:)345 636 y Fo(\017)25 b Ft(Add)19
b(the)g(additional)g(\002eld)g Fr(intersectClause)f Ft(to)h(the)g(data)
h(structures)f Fr(Query)g Ft(and)395 695 y Fr(InsertStmt)11
b Ft(de\002ned)h(in)g(the)g(\002le)h Fk(:)8 b(:)g(:)p
Fr(/src/include/nodes/parsenodes)o(.h)p Ft(:)454 819
y Fr(typedef)29 b(struct)h(Query)454 878 y({)514 938
y(NodeTag)119 b(type;)514 998 y(CmdType)g(commandType;)753
1058 y(.)753 1118 y(.)753 1177 y(.)514 1237 y(Node)209
b(*havingQual;)395 1297 y(+)89 b(List)209 b(*intersectClause;)514
1357 y(List)g(*unionClause;)514 1416 y(List)g(*base_relation_list_;)514
1476 y(List)g(*join_relation_list_;)454 1536 y(})30 b(Query;)454
1656 y(typedef)f(struct)h(InsertStmt)454 1715 y({)514
1775 y(NodeTag)119 b(type;)753 1835 y(.)753 1895 y(.)753
1954 y(.)514 2014 y(bool)209 b(unionall;)395 2074 y(+)89
b(List)209 b(*intersectClause;)454 2134 y(})30 b(InsertStmt;)345
2257 y Fo(\017)25 b Ft(Add)63 b(the)g(ne)o(w)g(ke)o(ywords)g
Fr(EXCEPT)g Ft(and)g Fr(INTERSECT)g Ft(to)g(the)g(\002le)395
2317 y Fk(:)8 b(:)g(:)p Fr(/src/backend/parser/keywords.)o(c)p
Ft(:)454 2440 y Fr(static)30 b(ScanKeyword)e(ScanKeywords[])g(=)i({)514
2500 y({"abort",)f(ABORT_TRANS},)514 2560 y({"action",)g(ACTION},)813
2620 y(.)813 2679 y(.)813 2739 y(.)514 2799 y({"end",)g(END_TRANS},)395
2859 y(+)89 b({"except",)29 b(EXCEPT},)813 2919 y(.)813
2978 y(.)813 3038 y(.)514 3098 y({"instead",)g(INSTEAD},)395
3158 y(+)89 b({"intersect",)29 b(INTERSECT},)813 3217
y(.)813 3277 y(.)813 3337 y(.)454 3397 y(};)p eop
%%Page: 97 97
97 96 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)349 b Ft(97)273
234 y Fo(\017)25 b Ft(PostgreSQL)14 b(contains)h(functions)g(to)f(con)n
(v)o(ert)h(the)g(internal)f(representation)g(of)h(a)g
Fp(parsetr)n(ee)323 294 y Ft(or)j Fp(plantr)n(ee)g Ft(into)g(an)h
(ASCII)f(representation)f(\(that)h(can)h(easily)g(be)f(printed)g(to)g
(the)h(screen)323 354 y(\(for)f(deb)o(ugging)g(purposes\))i(or)f(be)g
(stored)g(in)h(a)f(\002le\))g(and)g(vice)h(v)o(ersa.)37
b(These)21 b(functions)323 413 y(ha)o(v)o(e)g(to)g(be)h(adapted)f(to)g
(be)g(able)g(to)g(deal)h(with)f Fp(intersects)g Ft(and)h
Fp(e)o(xcepts)p Ft(.)43 b(These)22 b(func-)323 473 y(tions)e(can)h(be)g
(found)f(in)h(the)f(\002les)h Fk(:)8 b(:)g(:)p Fr
(/src/backend/nodes/outfuncs.c)18 b Ft(and)323 533 y
Fk(:)8 b(:)g(:)p Fr(/src/backend/nodes/readfuncs.)o(c)p
Ft(:)382 675 y Fr(static)30 b(void)382 735 y(_outQuery\(StringInfo)e
(str,)h(Query)h(*node\))382 795 y({)1159 854 y(.)1159
914 y(.)1159 974 y(.)442 1034 y(appendStringInfo\(str,)e(")h
(:unionClause)g("\);)442 1094 y(_outNode\(str,)g(node->unionClause\);)
323 1153 y(+)89 b(appendStringInfo\(str,)28 b(")h(:intersectClause)f
("\);)323 1213 y(+)89 b(_outNode\(str,)29 b(node->intersectClause\);)
382 1273 y(})382 1392 y(static)h(Query)f(*)382 1452 y(_readQuery\(\))
382 1512 y({)1159 1572 y(.)1159 1632 y(.)1159 1691 y(.)442
1751 y(token)g(=)h(lsptok\(NULL,)f(&length\);)442 1811
y(local_node->unionClause)e(=)j(nodeRead\(true\);)323
1871 y(+)89 b(token)29 b(=)h(lsptok\(NULL,)f(&length\);)323
1930 y(+)89 b(local_node->intersectClause)27 b(=)j(nodeRead\(true\);)
442 2050 y(return)f(\(local_node\);)382 2110 y(})273
2252 y Fo(\017)c Ft(The)14 b(function)g Fr(ExecReScan\(\))f
Ft(is)h(called)h(whene)o(v)o(er)f(a)g(ne)o(w)g(e)o(x)o(ecution)h(of)f
(a)g(gi)o(v)o(en)g Fp(plan)323 2312 y Ft(has)j(to)f(be)h(started)g
(\(i.e.)29 b(whene)o(v)o(er)16 b(we)h(ha)o(v)o(e)g(to)f(start)h(from)f
(the)g(be)o(ginning)g(with)h(the)f(\002rst)323 2371 y(tuple)k(again\).)
41 b(The)21 b(call)g(to)f(this)h(function)f(happens)h(implicitly)m(.)40
b(F)o(or)20 b(the)h(special)g(kind)323 2431 y(of)16 b(subqueries)h(we)g
(are)g(using)f(for)g(the)h(re)o(written)f(queries)g(\(see)h(e)o(xample)
g(3.5\))g(we)g(ha)o(v)o(e)g(to)323 2491 y(take)g(that)g(also)i
Fr(Group)e Ft(nodes)h(are)g(processed.)32 b(The)18 b(function)f(can)h
(be)g(found)f(in)h(the)f(\002le)323 2551 y Fk(l)q(dots)p
Fr(/backend/executor/execAmi.c)p Ft(.)382 2693 y Fr(void)382
2753 y(ExecReScan\(Plan)29 b(*node,)g(ExprContext)f(*exprCtxt,)711
2812 y(Plan)i(*parent\))382 2872 y({)1159 2932 y(.)1159
2992 y(.)1159 3052 y(.)472 3111 y(switch)f(\(nodeTag\(node\)\))472
3171 y({)1159 3231 y(.)1159 3291 y(.)1159 3350 y(.)p
eop
%%Page: 98 98
98 97 bop 270 60 a Ft(98)82 b Fm(CHAPTER)14 b(3.)28 b(POSTGRESQL)13
b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)395
234 y Fr(+)179 b(case)29 b(T_Group:)395 294 y(+)388 b
(ExecReScanGroup\(\(Group)27 b(*\))j(node,)395 354 y(+)896
b(exprCtxt,)29 b(parent\);)395 413 y(+)388 b(break;)1231
473 y(.)1231 533 y(.)1231 593 y(.)544 653 y(})454 712
y(})345 933 y Fo(\017)25 b Ft(The)g(function)e Fr(ExecReScanGroup\(\))g
Ft(is)i(called)f(by)h Fr(ExecReScan\(\))e Ft(described)395
993 y(abo)o(v)o(e)33 b(whene)o(v)o(er)g(a)g Fr(Group)g
Ft(node)g(is)g(detected)g(and)g(can)h(be)f(found)f(in)h(the)g(\002le)
395 1053 y Fk(:)8 b(:)g(:)p Fr(/src/backend/executor/nodeGro)o(up.c)i
Ft(.)18 b(It)13 b(has)g(been)g(created)g(for)g(the)g
Fp(in-)395 1112 y(tersect)e Ft(and)f Fp(e)o(xcept)h Ft(logic)f
(although)g(it)h(is)g(actually)f(needed)h(by)f(the)h(special)g(kind)f
(of)g(subselect)395 1172 y(\(see)i(abo)o(v)o(e\).)454
1365 y Fr(void)454 1424 y(ExecReScanGroup\(Group)28 b(*node,)h
(ExprContext)g(*exprCtxt,)933 1484 y(Plan)g(*parent\))454
1544 y({)514 1604 y(GroupState)g(*grpstate)g(=)h(node->grpstate;)514
1723 y(grpstate->grp_useFirstTuple)d(=)j(FALSE;)514 1783
y(grpstate->grp_done)e(=)i(FALSE;)514 1843 y(grpstate->grp_firstTuple)d
(=)j(\(HeapTupleData)e(*\)NIL;)514 1962 y(/*)544 2022
y(*)i(if)f(chgParam)g(of)h(subnode)f(is)h(not)f(null)h(then)f(plan)544
2082 y(*)h(will)f(be)h(re-scanned)f(by)g(first)h(ExecProcNode.)544
2142 y(*/)514 2201 y(if)g(\(\(\(Plan)f(*\))h
(node\)->lefttree->chgParam)d(==)i(NULL\))574 2261 y
(ExecReScan\(\(\(Plan)f(*\))i(node\)->lefttree,)903 2321
y(exprCtxt,)f(\(Plan)g(*\))g(node\);)454 2381 y(})270
2614 y Fn(Parser)270 2742 y Ft(The)12 b Fp(parser)g Ft(de\002ned)f(in)g
(the)g(\002le)g Fk(:)d(:)g(:)p Fr(/src/backend/parser/gram.y)g
Ft(had)j(to)h(be)f(modi\002ed)270 2801 y(in)h(two)g(ways:)345
2956 y Fo(\017)25 b Ft(The)17 b(grammar)f(had)g(to)h(be)g(adapted)g(to)
f(support)h(the)g(usage)g(of)f(parenthesis)h(\(to)f(be)h(able)g(to)395
3016 y(specify)12 b(the)g(order)g(of)g(e)o(x)o(ecution)g(of)g(the)h
(set)f(operators\).)345 3188 y Fo(\017)25 b Ft(The)10
b(code)f(b)o(uilding)g(up)h(the)f(data)h(structures)f(handed)h(back)g
(by)f(the)h Fp(parser)g Ft(had)g(to)f(be)h(inserted.)270
3342 y(Here)h(is)h(a)f(part)g(of)f(the)i(grammar)e(which)h(is)g
(responsible)g(for)g Fr(select)f Ft(statements)i(ha)o(ving)f(the)g
(code)270 3402 y(b)o(uilding)h(up)g(the)g(data)h(structures)f
(inserted:)p eop
%%Page: 99 99
99 98 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6 b(TION)14
b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)349 b Ft(99)258
234 y Fr(SelectStmt)29 b(:)59 b(select_w_o_sort)28 b(sort_clause)377
294 y({)1035 354 y(.)1035 413 y(.)1035 473 y(.)467 533
y(/*)i($1)f(holds)h(the)f(tree)h(built)f(up)h(by)f(the)497
593 y(*)h(rule)f('select_w_o_sort')497 653 y(*/)467 712
y(Node)g(*op)h(=)g(\(Node)f(*\))h($1;)467 832 y(if)g(IsA\($1,)f
(SelectStmt\))467 892 y({)527 951 y(SelectStmt)g(*n)g(=)h(\(SelectStmt)
f(*\)$1;)527 1011 y(n->sortClause)f(=)i($2;)527 1071
y($$)f(=)h(\(Node)g(*\)n;)467 1131 y(})467 1191 y(else)467
1250 y({)527 1310 y(/*)f(Create)h(a)f("flat)h(list")f(of)h(the)f
(operator)557 1370 y(*)g(tree)h(built)f(up)h(by)g('select_w_o_sort')e
(and)557 1430 y(*)h(let)h(select_list)f(point)g(to)h(it)557
1489 y(*/)527 1549 y(create_select_list\(\(Node)d(*\)op,)1095
1609 y(&select_list,)1095 1669 y(&unionall_present\);)527
1729 y(/*)i(Replace)h(all)f(the)h(A_Expr)f(nodes)g(in)h(the)557
1788 y(*)f(operator)g(tree)h(by)g(Expr)f(nodes.)557 1848
y(*/)557 1908 y(op)g(=)h(A_Expr_to_Expr\(op,)e(&intersect_present\);)
1035 1968 y(.)1035 2027 y(.)1035 2087 y(.)557 2147 y(/*)h(Get)h(the)f
(leftmost)g(SelectStmt)g(node)h(\(which)587 2207 y(*)f(automatically)g
(represents)g(the)g(first)g(Select)587 2267 y(*)g(Statement)g(of)h(the)
f(query!\))h(*/)557 2326 y(first_select)e(=)766 2386
y(\(SelectStmt)h(*\)lfirst\(select_list\);)557 2446 y(/*)g(Attach)h
(the)f(list)h(of)f(all)h(SelectStmt)f(nodes)587 2506
y(*)g(to)h(unionClause)587 2565 y(*/)557 2625 y
(first_select->unionClause)d(=)j(select_list;)557 2745
y(/*)f(Attach)h(the)f(whole)g(operator)g(tree)h(to)587
2804 y(*)f(intersectClause)g(*/)557 2864 y
(first_select->intersectClause)d(=)1423 2924 y(\(List)k(*\))f(op;)557
2984 y(/*)g(finally)g(attach)h(the)f(sort)h(clause)f(*/)557
3044 y(first_select->sortClause)e(=)j($2;)557 3163 y(/*)f(Now)h(hand)f
(it)h(back!)f(*/)557 3223 y($$)g(=)h(\(Node)f(*\)first_select;)497
3283 y(})377 3342 y(})258 3402 y(;)p eop
%%Page: 100 100
100 99 bop 270 60 a Ft(100)57 b Fm(CHAPTER)14 b(3.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
330 234 y Fr(select_w_o_sort)28 b(:)60 b('\(')29 b(select_w_o_sort)f
('\)')449 294 y({)509 354 y($$)i(=)g($2;)449 413 y(})330
473 y(|)59 b(SubSelect)449 533 y({)509 593 y($$)30 b(=)g($1;)449
653 y(})330 712 y(|)59 b(select_w_o_sort)29 b(EXCEPT)g(select_w_o_sort)
449 772 y({)509 832 y($$)h(=)g(\(Node)f(*\)makeA_Expr\(AND,NULL,$1,)
1017 892 y(makeA_Expr\(NOT,NULL,NULL,$3\)\);)449 951
y(})330 1011 y(|)59 b(select_w_o_sort)29 b(UNION)g(opt_union)g
(select_w_o_sort)449 1071 y({)509 1131 y(if)h(\(IsA\($4,)f
(SelectStmt\)\))509 1191 y({)569 1250 y(SelectStmt)g(*n)g(=)h
(\(SelectStmt)f(*\)$4;)569 1310 y(n->unionall)g(=)g($3;)509
1370 y(})509 1430 y($$)h(=)g(\(Node)f(*\)makeA_Expr\(OR,NULL,$1,$4\);)
449 1489 y(})330 1549 y(|)59 b(select_w_o_sort)29 b(INTERSECT)g
(select_w_o_sort)449 1609 y({)509 1669 y($$)h(=)g(\(Node)f
(*\)makeA_Expr\(AND,NULL,$1,$3\);)449 1729 y(})330 1788
y(;)330 1896 y(SubSelect)g(:)59 b(SELECT)30 b(opt_unique)e
(res_target_list2)718 1956 y(result)i(from_clause)e(where_clause)718
2016 y(group_clause)h(having_clause)390 2076 y({)449
2135 y(SelectStmt)g(*n)h(=)g(makeNode\(SelectStmt\);)449
2195 y(n->unique)f(=)h($2;)688 2255 y(.)688 2315 y(.)688
2375 y(.)449 2434 y(n->havingClause)f(=)g($8;)449 2494
y($$)h(=)g(\(Node)f(*\)n;)390 2554 y(})330 2614 y(;)270
2722 y Ft(The)e(ke)o(ywords)f Fr(SELECT)p Ft(,)h Fr(EXCEPT)p
Ft(,)g Fr(UNION)p Ft(,)g Fr(INTERSECT)p Ft(,)f Fr('\(')h
Ft(and)g Fr('\)')f Ft(are)h Fp(termi-)270 2782 y(nal)f(symbols)h
Ft(and)f Fr(SelectStmt)p Ft(,)k Fr(select)p 1170 2782
15 2 v 17 w(w)p 1217 2782 V 18 w(o)p 1265 2782 V 17 w(sort)p
Ft(,)g Fr(sort)p 1564 2782 V 18 w(clause)p Ft(,)g Fr(opt)p
1894 2782 V 17 w(union)p Ft(,)270 2841 y Fr(SubSelect)p
Ft(,)57 b Fr(opt)p 702 2841 V 18 w(unique)p Ft(,)h Fr(res)p
1060 2841 V 17 w(target)p 1257 2841 V 17 w(list2)p Ft(,)g
Fr(result)p Ft(,)g Fr(from)p 1864 2841 V 17 w(clause)p
Ft(,)270 2901 y Fr(where)p 423 2901 V 17 w(clause)p Ft(,)23
b Fr(group)p 805 2901 V 18 w(clause)p Ft(,)g Fr(having)p
1218 2901 V 17 w(clause)d Ft(are)h Fp(nonterminal)g(symbols)p
Ft(.)42 b(The)270 2961 y(symbols)13 b Fr(EXCEPT)p Ft(,)h
Fr(UNION)e Ft(and)i Fr(INTERSECT)e Ft(are)h Fp(left)g(associative)h
Ft(meaning)f(that)g(a)g(statement)270 3021 y(like:)330
3119 y Fr(select)29 b(*)h(from)f(A)330 3179 y(union)330
3239 y(select)g(*)h(from)f(B)330 3298 y(union)330 3358
y(select)g(*)h(from)f(C;)p eop
%%Page: 101 101
101 100 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)324
b Ft(101)198 234 y(will)12 b(be)g(treated)g(as:)258 343
y Fr(\(\(select)29 b(*)h(from)f(A)318 403 y(union)318
463 y(select)g(*)h(from)f(B\))318 523 y(union)318 583
y(select)g(*)h(from)f(C\))198 689 y Ft(The)13 b Fr(select)p
471 689 15 2 v 17 w(w)p 518 689 V 18 w(o)p 566 689 V
18 w(sort)f Ft(rule)g(b)o(uilds)g(up)h(an)f Fp(oper)o(ator)h(tr)n(ee)g
Ft(using)g(nodes)g(of)f(type)g Fr(A)p 1767 689 V 18 w(Expr)p
Ft(.)k(F)o(or)198 749 y(e)o(v)o(ery)f Fp(union)g Ft(an)h
Fr(OR)f Ft(node)g(is)h(created,)g(for)f(e)o(v)o(ery)g
Fp(intersect)h Ft(an)f Fr(AND)g Ft(node)h(and)f(for)g(e)o(v)o(ery)g
Fp(e)o(xcept)198 809 y Ft(and)d Fr(AND)30 b(NOT)12 b
Ft(node)g(b)o(uilding)f(up)h(a)g(representation)f(of)h(a)g(formula)f
(in)h(propositional)f(logic.)16 b(If)11 b(the)198 869
y(query)h(parsed)h(did)g(not)g(contain)f(an)o(y)i(set)f(operations)g
(the)f(rule)h(hands)g(back)g(a)g Fr(SelectStmt)f Ft(node)198
929 y(representing)g(the)h(query)f(otherwise)h(the)f(top)h(node)g(of)f
(the)h Fp(oper)o(ator)g(tr)n(ee)h Ft(is)f(returned.)j(Figure)c(3.11)198
988 y(sho)o(ws)h(a)f(typical)g Fp(oper)o(ator)h(tr)n(ee)g
Ft(returned)f(by)g(the)g Fr(select)p 1287 988 V 18 w(w)p
1335 988 V 18 w(o)p 1383 988 V 17 w(sort)g Ft(rule.)388
2579 y @beginspecial 145 @llx 244 @lly 467 @urx 547 @ury
3220 @rwi @setspecial
%%BeginDocument: figures/union_intersect_select_w_o_sort.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
143.0 574.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 990 1575 m 1890 1575 l 1890 2295 l 990 2295 l cp gs col-1 s gr 
% Polyline
n 990 2025 m 1890 2025 l gs col-1 s gr 
% Polyline
n 1440 2025 m 1440 2295 l gs col-1 s gr 
% Polyline
n 990 1800 m 1890 1800 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1215 1755 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1350 1980 m
gs 1 -1 sc (OR) col-1 sh gr
% Polyline
n 2025 450 m 2925 450 l 2925 1170 l 2025 1170 l cp gs col-1 s gr 
% Polyline
n 2025 900 m 2925 900 l gs col-1 s gr 
% Polyline
n 2475 900 m 2475 1170 l gs col-1 s gr 
% Polyline
n 2025 675 m 2925 675 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2250 630 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2340 855 m
gs 1 -1 sc (AND) col-1 sh gr
% Polyline
n 3060 1575 m 3960 1575 l 3960 2295 l 3060 2295 l cp gs col-1 s gr 
% Polyline
n 3060 2025 m 3960 2025 l gs col-1 s gr 
% Polyline
n 3510 2025 m 3510 2295 l gs col-1 s gr 
% Polyline
n 3060 1800 m 3960 1800 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3285 1755 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 1980 m
gs 1 -1 sc (NOT) col-1 sh gr
% Polyline
n 3060 2025 m 3510 2295 l gs col-1 s gr 
% Polyline
n 3510 2025 m 3060 2295 l gs col-1 s gr 
% Polyline
n 3285 2970 m 4185 2970 l 4185 3690 l 3285 3690 l cp gs col-1 s gr 
% Polyline
n 3285 3420 m 4185 3420 l gs col-1 s gr 
% Polyline
n 3735 3420 m 3735 3690 l gs col-1 s gr 
% Polyline
n 3285 3195 m 4185 3195 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3510 3150 m
gs 1 -1 sc (A_Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 3375 m
gs 1 -1 sc (AND) col-1 sh gr
% Polyline
gs  clippath
800 2617 m 694 2680 l 758 2575 l 643 2689 l 686 2732 l  cp clip
n 1215 2160 m 675 2700 l gs col-1 s gr gr

% arrowhead
n 800 2617 m 694 2680 l 758 2575 l 779 2596 l 800 2617 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2122 2575 m 2185 2680 l 2080 2617 l 2194 2732 l 2237 2689 l  cp clip
n 1665 2160 m 2205 2700 l gs col-1 s gr gr

% arrowhead
n 2122 2575 m 2185 2680 l 2080 2617 l 2101 2596 l 2122 2575 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1579 1518 m 1462 1560 l 1546 1468 l 1411 1558 l 1444 1608 l  cp clip
n 2250 1035 m 1440 1575 l gs col-1 s gr gr

% arrowhead
n 1579 1518 m 1462 1560 l 1546 1468 l 1562 1493 l 1579 1518 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3411 1458 m 3494 1550 l 3378 1508 l 3513 1598 l 3546 1548 l  cp clip
n 2707 1025 m 3517 1565 l gs col-1 s gr gr

% arrowhead
n 3411 1458 m 3494 1550 l 3378 1508 l 3395 1483 l 3411 1458 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3765 2823 m 3735 2943 l 3705 2823 l 3705 2985 l 3765 2985 l  cp clip
n 3735 2160 m 3735 2970 l gs col-1 s gr gr

% arrowhead
n 3765 2823 m 3735 2943 l 3705 2823 l 3735 2823 l 3765 2823 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3095 4012 m 2989 4075 l 3053 3970 l 2938 4084 l 2981 4127 l  cp clip
n 3510 3555 m 2970 4095 l gs col-1 s gr gr

% arrowhead
n 3095 4012 m 2989 4075 l 3053 3970 l 3074 3991 l 3095 4012 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4417 3970 m 4480 4075 l 4375 4012 l 4489 4127 l 4532 4084 l  cp clip
n 3960 3555 m 4500 4095 l gs col-1 s gr gr

% arrowhead
n 4417 3970 m 4480 4075 l 4375 4012 l 4396 3991 l 4417 3970 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 45 3555 m 1305 3555 l gs col-1 s gr 
% Polyline
n 45 3285 m 1305 3285 l gs col-1 s gr 
% Polyline
n 45 2700 m 1305 2700 l 1305 3825 l 45 3825 l cp gs col-1 s gr 
% Polyline
n 1035 2925 m 1035 3825 l gs col-1 s gr 
% Polyline
n 45 2925 m 1305 2925 l gs col-1 s gr 
% Polyline
n 1035 3285 m 1305 3555 l gs col-1 s gr 
% Polyline
n 1035 3555 m 1305 3285 l gs col-1 s gr 
% Polyline
n 1305 3555 m 1035 3825 l gs col-1 s gr 
% Polyline
n 1035 3555 m 1305 3825 l gs col-1 s gr 
% Polyline
n 1575 3555 m 2835 3555 l gs col-1 s gr 
% Polyline
n 1575 3285 m 2835 3285 l gs col-1 s gr 
% Polyline
n 1575 2700 m 2835 2700 l 2835 3825 l 1575 3825 l cp gs col-1 s gr 
% Polyline
n 2565 2925 m 2565 3825 l gs col-1 s gr 
% Polyline
n 1575 2925 m 2835 2925 l gs col-1 s gr 
% Polyline
n 2565 3285 m 2835 3555 l gs col-1 s gr 
% Polyline
n 2565 3555 m 2835 3285 l gs col-1 s gr 
% Polyline
n 2835 3555 m 2565 3825 l gs col-1 s gr 
% Polyline
n 2565 3555 m 2835 3825 l gs col-1 s gr 
% Polyline
n 2340 4950 m 3600 4950 l gs col-1 s gr 
% Polyline
n 2340 4680 m 3600 4680 l gs col-1 s gr 
% Polyline
n 2340 4095 m 3600 4095 l 3600 5220 l 2340 5220 l cp gs col-1 s gr 
% Polyline
n 3330 4320 m 3330 5220 l gs col-1 s gr 
% Polyline
n 2340 4320 m 3600 4320 l gs col-1 s gr 
% Polyline
n 3330 4680 m 3600 4950 l gs col-1 s gr 
% Polyline
n 3330 4950 m 3600 4680 l gs col-1 s gr 
% Polyline
n 3600 4950 m 3330 5220 l gs col-1 s gr 
% Polyline
n 3330 4950 m 3600 5220 l gs col-1 s gr 
% Polyline
n 3870 4950 m 5130 4950 l gs col-1 s gr 
% Polyline
n 3870 4680 m 5130 4680 l gs col-1 s gr 
% Polyline
n 3870 4095 m 5130 4095 l 5130 5220 l 3870 5220 l cp gs col-1 s gr 
% Polyline
n 4860 4320 m 4860 5220 l gs col-1 s gr 
% Polyline
n 3870 4320 m 5130 4320 l gs col-1 s gr 
% Polyline
n 4860 4680 m 5130 4950 l gs col-1 s gr 
% Polyline
n 4860 4950 m 5130 4680 l gs col-1 s gr 
% Polyline
n 5130 4950 m 4860 5220 l gs col-1 s gr 
% Polyline
n 4860 4950 m 5130 5220 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
585 3150 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
315 2880 m
gs 1 -1 sc (SeqScan \(A\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2115 3150 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1845 2880 m
gs 1 -1 sc (SeqScan \(B\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2880 4545 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2610 4275 m
gs 1 -1 sc (SeqScan \(C\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4410 4545 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4140 4275 m
gs 1 -1 sc (SeqScan \(D\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
90 3465 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
90 3735 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1620 3465 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1620 3735 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2385 4860 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2385 5130 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3915 4860 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3915 5130 m
gs 1 -1 sc (intersectClause) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 604 2688 a(Figure)g(3.11:)j Fp(Oper)o(ator)e(tr)n(ee)h
Ft(for)d Fl(\()p Fk(A)h Fo([)f Fk(B)r Fl(\))p Fo(n)p
Fl(\()p Fk(C)k Fo(\\)d Fk(D)q Fl(\))198 2864 y Ft(The)24
b(rule)f Fr(SelectStmt)g Ft(transforms)f(the)i Fp(oper)o(ator)g(tr)n
(ee)g Ft(b)o(uilt)f(of)g Fr(A)p 1552 2864 V 18 w(Expr)g
Ft(nodes)h(into)f(an)198 2924 y Fp(oper)o(ator)d(tr)n(ee)g
Ft(using)g Fr(Expr)f Ft(nodes)g(by)g(a)h(call)f(to)h(the)f(function)f
Fr(A)p 1447 2924 V 18 w(Expr)p 1585 2924 V 18 w(to)p
1663 2924 V 17 w(Expr\(\))h Ft(which)198 2984 y(additionally)13
b(replaces)h(e)o(v)o(ery)f Fr(OR)g Ft(node)h(by)f(an)h
Fr(AND)f Ft(node)h(and)f(vice)h(v)o(ersa.)20 b(This)14
b(is)g(performed)e(in)198 3044 y(order)g(to)g(be)g(able)h(to)f(use)h
(the)f(function)g Fr(cnfify\(\))f Ft(later)h(on.)198
3163 y(The)j Fp(tr)o(ansformations)g Ft(follo)o(wing)e(the)h
Fp(parser)h Ft(e)o(xpect)g(a)f Fr(SelectStmt)g Ft(node)g(to)g(be)h
(returned)e(by)198 3223 y(the)g(rule)f Fr(SelectStmt)f
Ft(and)i(not)f(an)h Fp(oper)o(ator)g(tr)n(ee)p Ft(.)18
b(So)12 b(if)g(the)g(rule)h Fr(select)p 1640 3223 V 17
w(w)p 1687 3223 V 18 w(o)p 1735 3223 V 18 w(sort)f Ft(hands)198
3283 y(back)h(such)h(a)f(node)g(\(meaning)g(that)g(the)g(query)f(did)h
(not)g(contain)g(an)o(y)g(set)h(operations\))e(we)h(just)h(ha)o(v)o(e)
198 3342 y(to)f(attach)h(the)g(data)f(structure)g(b)o(uilt)g(up)h(by)f
(the)h Fr(sort)p 1171 3342 V 17 w(clause)f Ft(rule)g(and)h(are)g
(\002nished,)g(b)o(ut)f(when)198 3402 y(we)g(get)f(an)g
Fp(oper)o(ator)h(tr)n(ee)g Ft(we)g(ha)o(v)o(e)g(to)f(perform)f(the)h
(follo)o(wing)f(steps:)p eop
%%Page: 102 102
102 101 bop 270 60 a Ft(102)57 b Fm(CHAPTER)14 b(3.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
345 234 y Fo(\017)25 b Ft(Create)17 b(a)h(\003at)f(list)g(of)g(all)h
Fr(SelectStmt)e Ft(nodes)i(of)f(the)g Fp(oper)o(ator)i(tr)n(ee)f
Ft(\(by)f(a)g(call)h(to)f(the)395 294 y(function)8 b
Fr(create)p 753 294 15 2 v 18 w(select)p 951 294 V 17
w(list\(\))p Ft(\))h(and)h(attach)g(the)f(list)h(to)g(the)g(\002eld)f
Fr(unionClause)395 354 y Ft(of)i(the)i(leftmost)f Fr(SelectStmt)f
Ft(\(see)i(ne)o(xt)f(step\).)345 463 y Fo(\017)25 b Ft(Find)d(the)i
(leftmost)e(leaf)h(\()p Fr(SelectStmt)f Ft(node\))h(of)g(the)g
Fp(oper)o(ator)h(tr)n(ee)g Ft(\(this)f(is)h(auto-)395
523 y(matically)h(the)h(\002rst)f(member)g(of)g(the)h(abo)o(v)o(e)g
(created)g(list)g(because)g(of)g(the)f(technique)395
583 y Fr(create)p 578 583 V 17 w(select)p 775 583 V 17
w(list\(\))12 b Ft(uses)h(to)f(create)h(the)f(list\).)345
692 y Fo(\017)25 b Ft(Attach)e(the)g(whole)g Fp(oper)o(ator)h(tr)n(ee)g
Ft(\(including)e(the)i(leftmost)e(node)h(itself\))g(to)g(the)g(\002eld)
395 752 y Fr(intersectClause)10 b Ft(of)i(the)h(leftmost)e
Fr(SelectStmt)h Ft(node.)345 861 y Fo(\017)25 b Ft(Attach)32
b(the)g(data)h(structure)f(b)o(uilt)g(up)g(by)h(the)f
Fr(sort)p 1480 861 V 18 w(clause)g Ft(rule)g(to)g(the)g(\002eld)395
921 y Fr(sortClause)11 b Ft(of)h(the)g(leftmost)g Fr(SelectStmt)f
Ft(node.)345 1030 y Fo(\017)25 b Ft(Hand)16 b(back)g(the)g(leftmost)g
Fr(SelectStmt)f Ft(node)h(\(with)g(the)g Fp(oper)o(ator)h(tr)n(ee)p
Ft(,)h(the)e(list)g(of)g(all)395 1090 y Fr(SelectStmt)11
b Ft(nodes)i(and)f(the)g Fr(sortClause)g Ft(attached)g(to)g(it\).)270
1197 y(Figure)i(3.12)i(sho)o(ws)g(the)f(\002nal)g(data)g(structure)g
(deri)o(v)o(ed)f(from)g(the)i Fp(oper)o(ator)g(tr)n(ee)g
Ft(sho)o(wn)f(in)g(\002gure)270 1257 y(3.11)e(handed)f(back)g(by)h(the)
f Fr(SelectStmt)f Ft(rule:)465 3167 y @beginspecial 145
@llx 212 @lly 466 @urx 579 @ury 3210 @rwi @setspecial
%%BeginDocument: figures/union_intersect_select.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
132.5 582.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 1800 1350 m 2700 1350 l 2700 2070 l 1800 2070 l cp gs col-1 s gr 
% Polyline
n 1800 1800 m 2700 1800 l gs col-1 s gr 
% Polyline
n 1800 1575 m 2700 1575 l gs col-1 s gr 
% Polyline
n 2430 1800 m 2430 2070 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2160 1755 m
gs 1 -1 sc (OR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2115 1530 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1980 1980 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 225 2475 m 1125 2475 l 1125 3195 l 225 3195 l cp gs col-1 s gr 
% Polyline
n 225 2925 m 1125 2925 l gs col-1 s gr 
% Polyline
n 225 2700 m 1125 2700 l gs col-1 s gr 
% Polyline
n 855 2925 m 855 3195 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
540 2880 m
gs 1 -1 sc (AND) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 2655 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
360 3105 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 1350 2925 m 1890 2925 l 1890 3195 l 1350 3195 l cp gs col-1 s gr 
% Polyline
n 1620 2925 m 1620 3195 l gs col-1 s gr 
% Polyline
n 2115 2925 m 2655 2925 l 2655 3195 l 2115 3195 l cp gs col-1 s gr 
% Polyline
n 2385 2925 m 2385 3195 l gs col-1 s gr 
% Polyline
n 2385 2925 m 2655 3195 l gs col-1 s gr 
% Polyline
n 2655 2925 m 2385 3195 l gs col-1 s gr 
% Polyline
n 2925 1800 m 3465 1800 l 3465 2070 l 2925 2070 l cp gs col-1 s gr 
% Polyline
n 3195 1800 m 3195 2070 l gs col-1 s gr 
% Polyline
n 3690 1800 m 4230 1800 l 4230 2070 l 3690 2070 l cp gs col-1 s gr 
% Polyline
n 3960 1800 m 3960 2070 l gs col-1 s gr 
% Polyline
n 3960 1800 m 4230 2070 l gs col-1 s gr 
% Polyline
n 4230 1800 m 3960 2070 l gs col-1 s gr 
% Polyline
gs  clippath
3543 1905 m 3663 1935 l 3543 1965 l 3705 1965 l 3705 1905 l  cp clip
n 3330 1935 m 3690 1935 l gs col-1 s gr gr

% arrowhead
n 3543 1905 m 3663 1935 l 3543 1965 l 3543 1935 l 3543 1905 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1710 810 m 2250 810 l 2250 1080 l 1710 1080 l cp gs col-1 s gr 
% Polyline
n 1980 810 m 1980 1080 l gs col-1 s gr 
% Polyline
n 3240 810 m 3780 810 l 3780 1080 l 3240 1080 l cp gs col-1 s gr 
% Polyline
n 3510 810 m 3510 1080 l gs col-1 s gr 
% Polyline
n 4005 810 m 4545 810 l 4545 1080 l 4005 1080 l cp gs col-1 s gr 
% Polyline
n 4275 810 m 4275 1080 l gs col-1 s gr 
% Polyline
n 4275 810 m 4545 1080 l gs col-1 s gr 
% Polyline
n 4545 810 m 4275 1080 l gs col-1 s gr 
% Polyline
n 2475 810 m 3015 810 l 3015 1080 l 2475 1080 l cp gs col-1 s gr 
% Polyline
n 2745 810 m 2745 1080 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2340 420 m
gs 1 -1 sc (SelectStmt \(B\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2430 225 m
gs 1 -1 sc (Pointer to) col-1 sh gr
% Polyline
n 2925 2475 m 3825 2475 l 3825 3195 l 2925 3195 l cp gs col-1 s gr 
% Polyline
n 2925 2925 m 3825 2925 l gs col-1 s gr 
% Polyline
n 2925 2700 m 3825 2700 l gs col-1 s gr 
% Polyline
n 3555 2925 m 3555 3195 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3240 2880 m
gs 1 -1 sc (NOT) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 2655 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 3105 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 4050 2925 m 4590 2925 l 4590 3195 l 4050 3195 l cp gs col-1 s gr 
% Polyline
n 4320 2925 m 4320 3195 l gs col-1 s gr 
% Polyline
n 4320 2925 m 4590 3195 l gs col-1 s gr 
% Polyline
n 4590 2925 m 4320 3195 l gs col-1 s gr 
% Polyline
n 2340 3600 m 3240 3600 l 3240 4320 l 2340 4320 l cp gs col-1 s gr 
% Polyline
n 2340 4050 m 3240 4050 l gs col-1 s gr 
% Polyline
n 2340 3825 m 3240 3825 l gs col-1 s gr 
% Polyline
n 2970 4050 m 2970 4320 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
2700 4005 m
gs 1 -1 sc (OR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2655 3780 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2520 4230 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 3465 4050 m 4005 4050 l 4005 4320 l 3465 4320 l cp gs col-1 s gr 
% Polyline
n 3735 4050 m 3735 4320 l gs col-1 s gr 
% Polyline
n 4230 4050 m 4770 4050 l 4770 4320 l 4230 4320 l cp gs col-1 s gr 
% Polyline
n 4500 4050 m 4500 4320 l gs col-1 s gr 
% Polyline
n 4500 4050 m 4770 4320 l gs col-1 s gr 
% Polyline
n 4770 4050 m 4500 4320 l gs col-1 s gr 
% Polyline
gs  clippath
3318 4155 m 3438 4185 l 3318 4215 l 3480 4215 l 3480 4155 l  cp clip
n 3105 4185 m 3465 4185 l gs col-1 s gr gr

% arrowhead
n 3318 4155 m 3438 4185 l 3318 4215 l 3318 4185 l 3318 4155 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4083 4155 m 4203 4185 l 4083 4215 l 4245 4215 l 4245 4155 l  cp clip
n 3870 4185 m 4230 4185 l gs col-1 s gr gr

% arrowhead
n 4083 4155 m 4203 4185 l 4083 4215 l 4083 4185 l 4083 4155 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1203 3030 m 1323 3060 l 1203 3090 l 1365 3090 l 1365 3030 l  cp clip
n 990 3060 m 1350 3060 l gs col-1 s gr gr

% arrowhead
n 1203 3030 m 1323 3060 l 1203 3090 l 1203 3060 l 1203 3030 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2778 1905 m 2898 1935 l 2778 1965 l 2940 1965 l 2940 1905 l  cp clip
n 2565 1935 m 2925 1935 l gs col-1 s gr gr

% arrowhead
n 2778 1905 m 2898 1935 l 2778 1965 l 2778 1935 l 2778 1905 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1968 3030 m 2088 3060 l 1968 3090 l 2130 3090 l 2130 3030 l  cp clip
n 1755 3060 m 2115 3060 l gs col-1 s gr gr

% arrowhead
n 1968 3030 m 2088 3060 l 1968 3090 l 1968 3060 l 1968 3030 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2328 915 m 2448 945 l 2328 975 l 2490 975 l 2490 915 l  cp clip
n 2115 945 m 2475 945 l gs col-1 s gr gr

% arrowhead
n 2328 915 m 2448 945 l 2328 975 l 2328 945 l 2328 915 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3858 915 m 3978 945 l 3858 975 l 4020 975 l 4020 915 l  cp clip
n 3645 945 m 4005 945 l gs col-1 s gr gr

% arrowhead
n 3858 915 m 3978 945 l 3858 975 l 3858 945 l 3858 915 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3093 915 m 3213 945 l 3093 975 l 3255 975 l 3255 915 l  cp clip
n 2880 945 m 3240 945 l gs col-1 s gr gr

% arrowhead
n 3093 915 m 3213 945 l 3093 975 l 3093 945 l 3093 915 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1563 915 m 1683 945 l 1563 975 l 1725 975 l 1725 915 l  cp clip
n 1350 945 m 1710 945 l gs col-1 s gr gr

% arrowhead
n 1563 915 m 1683 945 l 1563 975 l 1563 945 l 1563 915 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3903 3030 m 4023 3060 l 3903 3090 l 4065 3090 l 4065 3030 l  cp clip
n 3690 3060 m 4050 3060 l gs col-1 s gr gr

% arrowhead
n 3903 3030 m 4023 3060 l 3903 3090 l 3903 3060 l 3903 3030 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 225 4455 m 1485 4455 l gs col-1 s gr 
% Polyline
n 225 4185 m 1485 4185 l gs col-1 s gr 
% Polyline
n 225 3600 m 1485 3600 l 1485 4725 l 225 4725 l cp gs col-1 s gr 
% Polyline
n 1215 3825 m 1215 4725 l gs col-1 s gr 
% Polyline
n 225 3825 m 1485 3825 l gs col-1 s gr 
% Polyline
n 1215 4185 m 1485 4455 l gs col-1 s gr 
% Polyline
n 1215 4455 m 1485 4185 l gs col-1 s gr 
% Polyline
n 1215 4455 m 1485 4725 l gs col-1 s gr 
% Polyline
n 1485 4455 m 1215 4725 l gs col-1 s gr 
% Polyline
n 2025 5580 m 3285 5580 l gs col-1 s gr 
% Polyline
n 2025 5310 m 3285 5310 l gs col-1 s gr 
% Polyline
n 2025 4725 m 3285 4725 l 3285 5850 l 2025 5850 l cp gs col-1 s gr 
% Polyline
n 3015 4950 m 3015 5850 l gs col-1 s gr 
% Polyline
n 2025 4950 m 3285 4950 l gs col-1 s gr 
% Polyline
n 3015 5310 m 3285 5580 l gs col-1 s gr 
% Polyline
n 3015 5580 m 3285 5310 l gs col-1 s gr 
% Polyline
n 3015 5580 m 3285 5850 l gs col-1 s gr 
% Polyline
n 3285 5580 m 3015 5850 l gs col-1 s gr 
% Polyline
n 3825 5580 m 5085 5580 l gs col-1 s gr 
% Polyline
n 3825 5310 m 5085 5310 l gs col-1 s gr 
% Polyline
n 3825 4725 m 5085 4725 l 5085 5850 l 3825 5850 l cp gs col-1 s gr 
% Polyline
n 4815 4950 m 4815 5850 l gs col-1 s gr 
% Polyline
n 3825 4950 m 5085 4950 l gs col-1 s gr 
% Polyline
n 4815 5310 m 5085 5580 l gs col-1 s gr 
% Polyline
n 4815 5580 m 5085 5310 l gs col-1 s gr 
% Polyline
n 4815 5580 m 5085 5850 l gs col-1 s gr 
% Polyline
n 5085 5580 m 4815 5850 l gs col-1 s gr 
% Polyline
n 225 1080 m 1485 1080 l gs col-1 s gr 
% Polyline
n 225 810 m 1485 810 l gs col-1 s gr 
% Polyline
n 225 225 m 1485 225 l 1485 1350 l 225 1350 l cp gs col-1 s gr 
% Polyline
n 1215 450 m 1215 1350 l gs col-1 s gr 
% Polyline
n 225 450 m 1485 450 l gs col-1 s gr 
% Open spline
gs  clippath
2150 1238 m 2228 1333 l 2114 1286 l 2244 1383 l 2280 1335 l  cp clip
n 1350.0 1215.0 m 1710.0 1215.0 l
	1710.0 1215.0 2070.0 1215.0 2160.0 1282.5 DrawSplineSection
	2250.0 1350.0 l  gs col-1 s gr
 gr

% arrowhead
n 2150 1238 m 2228 1333 l 2114 1286 l 2132 1262 l 2150 1238 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
996 3548 m 877 3585 l 964 3497 l 826 3583 l 858 3633 l  cp clip
n 2250.0 3060.0 m 2205.0 3195.0 l
	2205.0 3195.0 2160.0 3330.0 1687.5 3352.5 DrawSplineSection
	1687.5 3352.5 1215.0 3375.0 1035.0 3487.5 DrawSplineSection
	855.0 3600.0 l  gs col-1 s gr
 gr

% arrowhead
n 996 3548 m 877 3585 l 964 3497 l 980 3522 l 996 3548 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
840 1499 m 857 1376 l 899 1493 l 883 1332 l 824 1338 l  cp clip
n 1485.0 3060.0 m 1462.5 2722.5 l
	1462.5 2722.5 1440.0 2385.0 1170.0 2092.5 DrawSplineSection
	1170.0 2092.5 900.0 1800.0 877.5 1575.0 DrawSplineSection
	855.0 1350.0 l  gs col-1 s gr
 gr

% arrowhead
n 840 1499 m 857 1376 l 899 1493 l 870 1496 l 840 1499 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
807 2404 m 695 2457 l 769 2358 l 644 2462 l 683 2508 l  cp clip
n 3060.0 1935.0 m 3037.5 2070.0 l
	3037.5 2070.0 3015.0 2205.0 1980.0 2227.5 DrawSplineSection
	1980.0 2227.5 945.0 2250.0 810.0 2362.5 DrawSplineSection
	675.0 2475.0 l  gs col-1 s gr
 gr

% arrowhead
n 807 2404 m 695 2457 l 769 2358 l 788 2381 l 807 2404 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3487 2375 m 3391 2453 l 3439 2339 l 3342 2469 l 3390 2505 l  cp clip
n 3825.0 1935.0 m 3802.5 2070.0 l
	3802.5 2070.0 3780.0 2205.0 3645.0 2250.0 DrawSplineSection
	3645.0 2250.0 3510.0 2295.0 3442.5 2385.0 DrawSplineSection
	3375.0 2475.0 l  gs col-1 s gr
 gr

% arrowhead
n 3487 2375 m 3391 2453 l 3439 2339 l 3463 2357 l 3487 2375 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
989 157 m 876 208 l 951 110 l 825 211 l 862 258 l  cp clip
n 1845.0 945.0 m 1845.0 630.0 l
	1845.0 630.0 1845.0 315.0 1755.0 202.5 DrawSplineSection
	1755.0 202.5 1665.0 90.0 1372.5 67.5 DrawSplineSection
	1372.5 67.5 1080.0 45.0 967.5 135.0 DrawSplineSection
	855.0 225.0 l  gs col-1 s gr
 gr

% arrowhead
n 989 157 m 876 208 l 951 110 l 970 133 l 989 157 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2644 606 m 2731 518 l 2695 636 l 2778 498 l 2727 467 l  cp clip
n 2610.0 945.0 m 2610.0 832.5 l
	2610.0 832.5 2610.0 720.0 2677.5 607.5 DrawSplineSection
	2745.0 495.0 l  gs col-1 s gr
 gr

% arrowhead
n 2644 606 m 2731 518 l 2695 636 l 2669 621 l 2644 606 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3511 563 m 3623 511 l 3549 610 l 3675 509 l 3638 462 l  cp clip
n 3375.0 945.0 m 3397.5 810.0 l
	3397.5 810.0 3420.0 675.0 3532.5 585.0 DrawSplineSection
	3645.0 495.0 l  gs col-1 s gr
 gr

% arrowhead
n 3511 563 m 3623 511 l 3549 610 l 3530 587 l 3511 563 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4488 527 m 4610 505 l 4513 582 l 4661 516 l 4637 461 l  cp clip
n 4140.0 945.0 m 4185.0 810.0 l
	4185.0 810.0 4230.0 675.0 4432.5 585.0 DrawSplineSection
	4635.0 495.0 l  gs col-1 s gr
 gr

% arrowhead
n 4488 527 m 4610 505 l 4513 582 l 4501 555 l 4488 527 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2927 3539 m 2811 3584 l 2892 3490 l 2760 3584 l 2795 3633 l  cp clip
n 4185.0 3060.0 m 4162.5 3195.0 l
	4162.5 3195.0 4140.0 3330.0 3622.5 3352.5 DrawSplineSection
	3622.5 3352.5 3105.0 3375.0 2947.5 3487.5 DrawSplineSection
	2790.0 3600.0 l  gs col-1 s gr
 gr

% arrowhead
n 2927 3539 m 2811 3584 l 2892 3490 l 2910 3515 l 2927 3539 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2780 4642 m 2674 4705 l 2738 4600 l 2623 4714 l 2666 4757 l  cp clip
n 3600.0 4185.0 m 3555.0 4297.5 l
	3555.0 4297.5 3510.0 4410.0 3195.0 4455.0 DrawSplineSection
	3195.0 4455.0 2880.0 4500.0 2767.5 4612.5 DrawSplineSection
	2655.0 4725.0 l  gs col-1 s gr
 gr

% arrowhead
n 2780 4642 m 2674 4705 l 2738 4600 l 2759 4621 l 2780 4642 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4437 4576 m 4446 4699 l 4380 4595 l 4431 4749 l 4488 4730 l  cp clip
n 4365.0 4185.0 m 4365.0 4320.0 l
	4365.0 4320.0 4365.0 4455.0 4410.0 4590.0 DrawSplineSection
	4455.0 4725.0 l  gs col-1 s gr
 gr

% arrowhead
n 4437 4576 m 4446 4699 l 4380 4595 l 4409 4586 l 4437 4576 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
3330 420 m
gs 1 -1 sc (SelectStmt \(C\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3420 225 m
gs 1 -1 sc (Pointer to) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4320 420 m
gs 1 -1 sc (SelectStmt \(D\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4410 225 m
gs 1 -1 sc (Pointer to) col-1 sh gr
/Times-Roman ff 150.00 scf sf
765 4050 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 3780 m
gs 1 -1 sc (SelectStmt \(B\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2565 5175 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2205 4905 m
gs 1 -1 sc (SelectStmt \(C\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4365 5175 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
4005 4905 m
gs 1 -1 sc (SelectStmt \(D\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
765 675 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
405 405 m
gs 1 -1 sc (SelectStmt \(A\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 990 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 1260 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 4365 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 4635 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2070 5490 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2070 5760 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3870 5490 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3870 5760 m
gs 1 -1 sc (intersectClause) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 537 3277 a(Figure)g(3.12:)16 b(Data)c(structure)g(handed)g
(back)h(by)f Fr(SelectStmt)g Ft(rule)p eop
%%Page: 103 103
103 102 bop 198 60 a Fm(3.8.)26 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)327
b Ft(103)198 234 y(Here)26 b(is)g(a)g(description)g(of)f(the)h(abo)o(v)
o(e)g(used)h(functions.)56 b(The)o(y)26 b(can)g(be)g(found)g(in)f(the)h
(\002le)198 294 y Fk(:)8 b(:)g(:)p Fr(/src/backend/parser/anlayze.c)p
Ft(.)273 398 y Fo(\017)25 b Fr(create)p 506 398 15 2
v 17 w(select)p 703 398 V 17 w(list\(\))p Ft(:)323 457
y(This)15 b(function)f(steps)i(through)e(the)h Fp(tr)n(ee)g
Ft(handed)g(to)g(it)f(by)h(the)g(parameter)f Fr(ptr)h
Ft(and)g(creates)323 517 y(a)h(list)g(of)g(all)g Fr(SelectStmt)f
Ft(nodes)h(found.)27 b(The)17 b(list)f(is)g(handed)g(back)h(by)f(the)g
(parameter)323 577 y Fr(select)p 506 577 V 17 w(list)p
Ft(.)f(The)e(function)f(uses)h(a)g(recursi)o(v)o(e)f
Fp(depth)g(\002rst)g(sear)n(c)o(h)i Ft(algorithm)d(to)h(e)o(xam-)323
637 y(ine)g(the)g Fp(tr)n(ee)h Ft(leading)g(to)f(the)g(fact)g(that)g
(the)h(leftmost)e Fr(SelectStmt)h Ft(node)g(will)g(appear)g(\002rst)323
696 y(in)g(the)g(created)g(list.)382 821 y Fr(void)382
881 y(create_select_list\(Node)28 b(*ptr,)h(List)g(**select_list,)950
941 y(bool)h(*unionall_present\))382 1001 y({)442 1060
y(if\(IsA\(ptr,)f(SelectStmt\)\))442 1120 y({)502 1180
y(*select_list)f(=)i(lappend\(*select_list,)e(ptr\);)502
1240 y(if\(\(\(SelectStmt)g(*\)ptr\)->unionall)g(==)i(TRUE\))562
1299 y(*unionall_present)e(=)h(TRUE;)502 1359 y(return;)442
1419 y(})442 1539 y(/*)h(Recursively)e(call)i(for)f(all)h(arguments.)
472 1598 y(*)g(A)g(NOT)f(expr)h(has)f(no)h(lexpr!)472
1658 y(*/)442 1718 y(if)g(\(\(\(A_Expr)f(*\)ptr\)->lexpr)f(!=)i(NULL\))
502 1778 y(create_select_list\(\(\(A_Expr)d(*\)ptr\)->lexpr,)1010
1837 y(select_list,)h(unionall_present\);)442 1897 y
(create_select_list\(\(\(A_Expr)f(*\)ptr\)->rexpr,)1010
1957 y(select_list,)h(unionall_present\);)323 2017 y(})273
2142 y Fo(\017)d Fr(A)p 356 2142 V 17 w(Expr)p 493 2142
V 18 w(to)p 571 2142 V 18 w(Expr\(\))p Ft(:)323 2201
y(This)14 b(function)e(recursi)o(v)o(ely)h(steps)h(through)e(the)i
Fp(oper)o(ator)g(tr)n(ee)g Ft(handed)f(to)g(it)g(by)h(the)f(param-)323
2261 y(eter)k Fr(ptr)g Ft(and)h(replaces)g Fr(A)p 826
2261 V 18 w(Expr)f Ft(nodes)h(by)f Fr(Expr)h Ft(nodes.)31
b(Additionally)17 b(it)g(e)o(xchanges)323 2321 y Fr(AND)e
Ft(nodes)h(with)g Fr(OR)f Ft(nodes)h(and)g(vice)g(v)o(ersa.)27
b(The)16 b(reason)g(for)f(this)h(e)o(xchange)g(is)g(easy)g(to)323
2381 y(understand.)27 b(W)l(e)17 b(implement)e Fp(intersect)i
Ft(and)f Fp(e)o(xcept)h Ft(clauses)g(by)f(re)o(writing)f(these)i
(queries)323 2441 y(to)d(semantically)h(equi)o(v)o(alent)f(queries)h
(that)g(use)g Fr(IN)g Ft(and)g Fr(NOT)29 b(IN)15 b Ft(subselects.)25
b(T)l(o)15 b(be)g(able)323 2500 y(to)d(use)h(all)f(three)h(operations)f
(\()p Fp(unions)p Ft(,)h Fp(intersects)g Ft(and)f Fp(e)o(xcepts)p
Ft(\))h(in)f(one)h(comple)o(x)g(query)m(,)f(we)323 2560
y(ha)o(v)o(e)18 b(to)g(translate)h(the)f(queries)g(into)g
Fp(Disjunctive)g(Normal)h(F)-5 b(orm)19 b Ft(\(DNF\).)f(Unfortunately)
323 2620 y(there)12 b(is)g(no)h(function)e Fr(dnfify\(\))p
Ft(,)i(b)o(ut)f(there)g(is)h(a)g(function)e Fr(cnfify\(\))h
Ft(which)g(produces)323 2680 y(DNF)17 b(when)g(we)h(e)o(xchange)g
Fr(AND)g Ft(nodes)g(with)f Fr(OR)g Ft(nodes)h(and)g(vice)f(v)o(ersa)h
(before)f(calling)323 2739 y Fr(cnfify\(\))11 b Ft(and)h(e)o(xchange)h
(them)f(again)g(in)h(the)f(result.)382 2864 y Fr(Node)30
b(*)382 2924 y(A_Expr_to_Expr\(Node)e(*ptr,)831 2984
y(bool)h(*intersect_present\))382 3044 y({)442 3103 y(Node)h(*result;)
442 3223 y(switch\(nodeTag\(ptr\)\))442 3283 y({)502
3342 y(case)f(T_A_Expr:)502 3402 y({)p eop
%%Page: 104 104
104 103 bop 270 60 a Ft(104)60 b Fm(CHAPTER)14 b(3.)25
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
634 234 y Fr(A_Expr)29 b(*a)h(=)f(\(A_Expr)g(*\)ptr;)634
354 y(switch)g(\(a->oper\))634 413 y({)693 473 y(case)h(AND:)693
533 y({)753 593 y(Expr)g(*expr)f(=)h(makeNode\(Expr\);)753
653 y(Node)g(*lexpr)f(=)843 712 y(A_Expr_to_Expr\(\(\(A_Expr)e
(*\)ptr\)->lexpr,)1291 772 y(intersect_present\);)753
832 y(Node)j(*rexpr)f(=)843 892 y(A_Expr_to_Expr\(\(\(A_Expr)e
(*\)ptr\)->rexpr,)1291 951 y(intersect_present\);)753
1071 y(*intersect_present)h(=)i(TRUE;)753 1191 y(expr->typeOid)f(=)g
(BOOLOID;)753 1250 y(expr->opType)g(=)h(OR_EXPR;)753
1310 y(expr->args)f(=)h(makeList\(lexpr,)e(rexpr,)h(-1\);)753
1370 y(result)g(=)h(\(Node)g(*\))f(expr;)753 1430 y(break;)693
1489 y(})693 1549 y(case)h(OR:)693 1609 y({)753 1669
y(Expr)g(*expr)f(=)h(makeNode\(Expr\);)753 1729 y(Node)g(*lexpr)f(=)843
1788 y(A_Expr_to_Expr\(\(\(A_Expr)e(*\)ptr\)->lexpr,)1291
1848 y(intersect_present\);)753 1908 y(Node)j(*rexpr)f(=)843
1968 y(A_Expr_to_Expr\(\(\(A_Expr)e(*\)ptr\)->rexpr,)1291
2027 y(intersect_present\);)753 2147 y(expr->typeOid)i(=)g(BOOLOID;)753
2207 y(expr->opType)g(=)h(AND_EXPR;)753 2267 y(expr->args)f(=)h
(makeList\(lexpr,)e(rexpr,)h(-1\);)753 2326 y(result)g(=)h(\(Node)g
(*\))f(expr;)753 2386 y(break;)693 2446 y(})693 2506
y(case)h(NOT:)693 2565 y({)753 2625 y(Expr)g(*expr)f(=)h
(makeNode\(Expr\);)753 2685 y(Node)g(*rexpr)f(=)843 2745
y(A_Expr_to_Expr\(\(\(A_Expr)e(*\)ptr\)->rexpr,)1291
2804 y(intersect_present\);)753 2924 y(expr->typeOid)i(=)g(BOOLOID;)753
2984 y(expr->opType)g(=)h(NOT_EXPR;)753 3044 y(expr->args)f(=)h
(makeList\(rexpr,)e(-1\);)753 3103 y(result)h(=)h(\(Node)g(*\))f(expr;)
753 3163 y(break;)693 3223 y(})634 3283 y(})634 3342
y(break;)574 3402 y(})p eop
%%Page: 105 105
105 104 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)324
b Ft(105)502 234 y Fr(default:)502 294 y({)562 354 y(result)29
b(=)h(ptr;)502 413 y(})442 473 y(})382 533 y(})382 593
y(return)g(result;)323 653 y(})198 787 y Ft(Note)11 b(that)g(the)g
Fr(stmtmulti)f Ft(and)h Fr(OptStmtMulti)f Ft(rules)h(had)g(to)g(be)g
(changed)g(in)g(order)f(to)h(a)o(v)o(oid)198 847 y Fp(shift/r)n(educe)
16 b Ft(con\003icts.)26 b(The)17 b(old)e(rules)h(allo)o(wed)g(an)g(in)n
(v)o(alid)f(syntax)h(\(e.g.)26 b(the)16 b(concatenation)g(of)198
907 y(two)c(statements)i(without)e(a)i(';')e(inbetween\))h(which)g
(will)g(be)g(pre)o(v)o(ented)g(no)o(w)m(.)k(The)d(ne)o(w)f(rules)g(ha)o
(v)o(e)198 967 y(the)f(second)h(line)f(commented)g(out)g(as)h(sho)o(wn)
f(belo)o(w:)258 1082 y Fr(stmtmulti)208 b(:)60 b(stmtmulti)29
b(stmt)g(';')646 1142 y(/*)h(|)60 b(stmtmulti)29 b(stmt)g(*/)736
1201 y(|)60 b(stmt)29 b(';')736 1261 y(;)258 1381 y(OptStmtMulti)118
b(:)60 b(OptStmtMulti)28 b(OptimizableStmt)g(';')646
1440 y(/*)i(|)60 b(OptStmtMulti)28 b(OptimizableStmt)g(*/)736
1500 y(|)60 b(OptimizableStmt)28 b(';')736 1560 y(;)198
1714 y Fn(T)l(ransf)o(ormations)198 1814 y Ft(This)17
b(step)g(normally)f(transforms)f(e)o(v)o(ery)i Fr(SelectStmt)e
Ft(node)i(found)f(into)g(a)g Fr(Query)h Ft(node)f(and)198
1874 y(does)f(a)f(lot)g(of)g(transformations)f(to)h(the)h
Fp(tar)n(getlist)p Ft(,)g(the)f Fr(where)g Ft(quali\002cation)f(etc.)22
b(As)15 b(mentioned)198 1934 y(abo)o(v)o(e)d(this)g(stage)g(e)o(xpects)
g(a)g Fr(SelectStmt)f Ft(node)g(and)h(cannot)g(handle)f(an)h
Fr(A)p 1603 1934 15 2 v 18 w(Expr)f Ft(node.)k(That')m(s)198
1994 y(why)d(we)h(did)f(the)g(changes)h(to)f(the)g Fp(oper)o(ator)h(tr)
n(ee)h Ft(sho)o(wn)e(in)g(\002gure)g(3.12.)198 2113 y(In)g(this)g
(stage)h(only)f(v)o(ery)g(fe)o(w)g(changes)h(ha)o(v)o(e)g(been)f
(necessary:)273 2224 y Fo(\017)25 b Ft(The)13 b(transformation)e(of)h
(the)g(list)h(attached)g(to)f Fr(unionClause)f Ft(is)i(pre)o(v)o
(ented.)j(The)d(ra)o(w)g(list)323 2284 y(is)g(no)o(w)h(passed)g
(through)f(instead)g(and)h(the)f(necessary)i(transformations)d(are)h
(performed)f(at)i(a)323 2344 y(later)e(point)f(in)i(time.)273
2459 y Fo(\017)25 b Ft(The)20 b(additionally)e(introduced)h(\002eld)g
Fr(intersectClause)f Ft(is)h(also)h(passed)g(untouched)323
2519 y(through)11 b(this)h(stage.)198 2630 y(The)29 b(changes)f
(described)g(in)g(the)g(abo)o(v)o(e)g(paragraph)g(ha)o(v)o(e)g(been)g
(applied)g(to)g(the)g(functions)198 2690 y Fr(transformInsertStmt\(\))
17 b Ft(and)i Fr(transformSelectStmt\(\))e Ft(which)i(are)g(contained)
198 2749 y(in)12 b(the)h(\002le)f Fk(:)c(:)g(:)p Fr
(/src/backend/parser/analyze.c)p Ft(:)273 2861 y Fo(\017)25
b Fr(transformInsertStmt\(\))p Ft(:)382 2995 y Fr(static)30
b(Query)f(*)382 3055 y(transformInsertStmt\(ParseState)e(*pstate,)980
3115 y(InsertStmt)i(*stmt\))382 3175 y({)1159 3235 y(.)1159
3294 y(.)1159 3354 y(.)p eop
%%Page: 106 106
106 105 bop 270 60 a Ft(106)57 b Fm(CHAPTER)14 b(3.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
514 234 y Fr(/*)30 b(Just)f(pass)h(through)f(the)g(unionClause)g(and)
544 294 y(*)h(intersectClause.)e(We)i(will)f(process)g(it)h(in)544
354 y(*)g(the)f(function)g(Except_Intersect_Rewrite\(\))544
413 y(*/)514 473 y(qry->unionClause)f(=)i(stmt->unionClause;)514
533 y(qry->intersectClause)e(=)i(stmt->intersectClause;)1231
593 y(.)1231 653 y(.)1231 712 y(.)514 832 y(return)f(\(Query)h(*\))f
(qry;)454 892 y(})345 1043 y Fo(\017)c Fr(transformSelectStmt\(\))p
Ft(:)454 1180 y Fr(static)30 b(Query)f(*)454 1240 y
(transformSelectStmt\(ParseState)e(*pstate,)1052 1300
y(SelectStmt)i(*stmt\))454 1360 y({)1231 1419 y(.)1231
1479 y(.)1231 1539 y(.)514 1599 y(/*)h(Just)f(pass)h(through)f(the)g
(unionClause)g(and)544 1658 y(*)h(intersectClause.)e(We)i(will)f
(process)g(it)h(in)544 1718 y(*)g(the)f(function)g
(Except_Intersect_Rewrite\(\))544 1778 y(*/)514 1838
y(qry->unionClause)f(=)i(stmt->unionClause;)514 1898
y(qry->intersectClause)e(=)i(stmt->intersectClause;)1231
1957 y(.)1231 2017 y(.)1231 2077 y(.)514 2137 y(return)f(\(Query)h(*\))
f(qry;)454 2196 y(})270 2353 y Fn(The)12 b(Rewrite)h(System)270
2455 y Ft(In)24 b(this)h(stage)g(the)f(information)f(contained)h(in)g
(the)h Fp(oper)o(ator)g(tr)n(ee)g Ft(attached)g(to)f(the)g(topmost)270
2515 y Fr(SelectStmt)18 b Ft(node)i(is)g(used)g(to)f(form)f(a)i(tree)f
(of)g Fr(Query)g Ft(nodes)h(representing)f(the)g(re)o(written)270
2574 y(query)c(\(i.e.)25 b(the)15 b(semantically)g(equi)o(v)o(alent)g
(query)g(that)g(contains)h(only)f Fp(union)g Ft(b)o(ut)g(no)g
Fp(intersect)h Ft(or)270 2634 y Fp(e)o(xcept)d Ft(operations\).)270
2754 y(The)g(follo)o(wing)e(steps)i(ha)o(v)o(e)g(to)f(be)g(performed:)
345 2867 y Fo(\017)25 b Ft(Sa)o(v)o(e)16 b(the)g Fr(sortClause)p
Ft(,)g Fr(uniqueFlag)p Ft(,)g Fr(targetList)f Ft(\002elds)h(etc.)27
b(of)16 b(the)f(topmost)395 2926 y Fr(Query)f Ft(node)g(because)h(the)f
(topmost)h(node)f(may)g(change)h(during)e(the)i(re)o(write)e(process)i
(\(re-)395 2986 y(member)f(\(only\))f(the)i(topmost)g
Fr(SelectStmt)f Ft(node)h(has)g(already)f(been)h(transformed)f(to)h(a)
395 3046 y Fr(Query)c Ft(node\).)345 3163 y Fo(\017)25
b Ft(Recursi)o(v)o(ely)12 b(step)h(through)e(the)h Fp(oper)o(ator)h(tr)
n(ee)g Ft(and)g(transform)e(e)o(v)o(ery)h Fr(SelectStmt)f
Ft(node)395 3223 y(to)18 b(a)h Fr(Query)f Ft(node)g(using)h(the)f
(function)g Fr(intersect)p 1440 3223 15 2 v 17 w(tree)p
1577 3223 V 17 w(analyze\(\))g Ft(described)395 3283
y(belo)o(w)m(.)d(The)d(one)g(node)g(already)f(transformed)g(\(the)h
(topmost)f(node\))h(is)g(still)g(contained)f(in)h(the)395
3342 y Fp(oper)o(ator)j(tr)n(ee)g Ft(and)f(must)g(not)h(be)f
(transformed)f(again)h(because)h(this)g(would)e(cause)j(troubles)395
3402 y(in)c(the)g Fp(tr)o(ansforming)h(logic)p Ft(.)p
eop
%%Page: 107 107
107 106 bop 198 60 a Fm(3.8.)26 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)327
b Ft(107)433 2199 y @beginspecial 173 @llx 194 @lly 439
@urx 597 @ury 2660 @rwi @setspecial
%%BeginDocument: figures/union_intersect_dnf.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
149.0 635.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 675 810 m 675 1350 l 405 1350 l 405 810 l cp gs col-1 s gr 
% Polyline
n 675 1080 m 405 1080 l gs col-1 s gr 
% Polyline
n 675 4095 m 675 4635 l 405 4635 l 405 4095 l cp gs col-1 s gr 
% Polyline
n 675 4365 m 405 4365 l gs col-1 s gr 
% Polyline
n 675 4365 m 405 4635 l gs col-1 s gr 
% Polyline
n 675 4635 m 405 4365 l gs col-1 s gr 
% Polyline
gs  clippath
888 4200 m 1008 4230 l 888 4260 l 1050 4260 l 1050 4200 l  cp clip
n 1035 4230 m 540 4230 l gs col-1 s gr gr

% arrowhead
n 888 4200 m 1008 4230 l 888 4260 l 888 4230 l 888 4200 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2925 4905 m 3825 4905 l 3825 5625 l 2925 5625 l cp gs col-1 s gr 
% Polyline
n 2925 5355 m 3825 5355 l gs col-1 s gr 
% Polyline
n 2925 5130 m 3825 5130 l gs col-1 s gr 
% Polyline
n 3555 5355 m 3555 5625 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3240 5310 m
gs 1 -1 sc (NOT) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 5085 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 5535 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 4050 5355 m 4590 5355 l 4590 5625 l 4050 5625 l cp gs col-1 s gr 
% Polyline
n 4320 5355 m 4320 5625 l gs col-1 s gr 
% Polyline
n 4320 5355 m 4590 5625 l gs col-1 s gr 
% Polyline
n 4590 5355 m 4320 5625 l gs col-1 s gr 
% Polyline
gs  clippath
3903 5460 m 4023 5490 l 3903 5520 l 4065 5520 l 4065 5460 l  cp clip
n 3690 5490 m 4050 5490 l gs col-1 s gr gr

% arrowhead
n 3903 5460 m 4023 5490 l 3903 5520 l 3903 5490 l 3903 5460 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2160 4365 m 2700 4365 l 2700 4635 l 2160 4635 l cp gs col-1 s gr 
% Polyline
n 2430 4365 m 2430 4635 l gs col-1 s gr 
% Polyline
n 2925 4365 m 3465 4365 l 3465 4635 l 2925 4635 l cp gs col-1 s gr 
% Polyline
n 3195 4365 m 3195 4635 l gs col-1 s gr 
% Polyline
n 3195 4365 m 3465 4635 l gs col-1 s gr 
% Polyline
n 3465 4365 m 3195 4635 l gs col-1 s gr 
% Polyline
gs  clippath
2778 4470 m 2898 4500 l 2778 4530 l 2940 4530 l 2940 4470 l  cp clip
n 2565 4500 m 2925 4500 l gs col-1 s gr gr

% arrowhead
n 2778 4470 m 2898 4500 l 2778 4530 l 2778 4500 l 2778 4470 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1035 3915 m 1935 3915 l 1935 4635 l 1035 4635 l cp gs col-1 s gr 
% Polyline
n 1035 4365 m 1935 4365 l gs col-1 s gr 
% Polyline
n 1035 4140 m 1935 4140 l gs col-1 s gr 
% Polyline
n 1665 4365 m 1665 4635 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1395 4320 m
gs 1 -1 sc (OR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1350 4095 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1215 4545 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 2925 1620 m 3825 1620 l 3825 2340 l 2925 2340 l cp gs col-1 s gr 
% Polyline
n 2925 2070 m 3825 2070 l gs col-1 s gr 
% Polyline
n 2925 1845 m 3825 1845 l gs col-1 s gr 
% Polyline
n 3555 2070 m 3555 2340 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3240 2025 m
gs 1 -1 sc (NOT) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 1800 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 2250 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 4050 2070 m 4590 2070 l 4590 2340 l 4050 2340 l cp gs col-1 s gr 
% Polyline
n 4320 2070 m 4320 2340 l gs col-1 s gr 
% Polyline
n 4320 2070 m 4590 2340 l gs col-1 s gr 
% Polyline
n 4590 2070 m 4320 2340 l gs col-1 s gr 
% Polyline
gs  clippath
3903 2175 m 4023 2205 l 3903 2235 l 4065 2235 l 4065 2175 l  cp clip
n 3690 2205 m 4050 2205 l gs col-1 s gr gr

% arrowhead
n 3903 2175 m 4023 2205 l 3903 2235 l 3903 2205 l 3903 2175 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 2160 1080 m 2700 1080 l 2700 1350 l 2160 1350 l cp gs col-1 s gr 
% Polyline
n 2430 1080 m 2430 1350 l gs col-1 s gr 
% Polyline
n 2925 1080 m 3465 1080 l 3465 1350 l 2925 1350 l cp gs col-1 s gr 
% Polyline
n 3195 1080 m 3195 1350 l gs col-1 s gr 
% Polyline
n 3195 1080 m 3465 1350 l gs col-1 s gr 
% Polyline
n 3465 1080 m 3195 1350 l gs col-1 s gr 
% Polyline
gs  clippath
2778 1185 m 2898 1215 l 2778 1245 l 2940 1245 l 2940 1185 l  cp clip
n 2565 1215 m 2925 1215 l gs col-1 s gr gr

% arrowhead
n 2778 1185 m 2898 1215 l 2778 1245 l 2778 1215 l 2778 1185 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1035 630 m 1935 630 l 1935 1350 l 1035 1350 l cp gs col-1 s gr 
% Polyline
n 1035 1080 m 1935 1080 l gs col-1 s gr 
% Polyline
n 1035 855 m 1935 855 l gs col-1 s gr 
% Polyline
n 1665 1080 m 1665 1350 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1395 1035 m
gs 1 -1 sc (OR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1350 810 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1215 1260 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
gs  clippath
570 3948 m 540 4068 l 510 3948 l 510 4110 l 570 4110 l  cp clip
n 540 1215 m 540 4095 l gs col-1 s gr gr

% arrowhead
n 570 3948 m 540 4068 l 510 3948 l 540 3948 l 570 3948 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
888 915 m 1008 945 l 888 975 l 1050 975 l 1050 915 l  cp clip
n 540 945 m 1035 945 l gs col-1 s gr gr

% arrowhead
n 888 915 m 1008 945 l 888 975 l 888 945 l 888 915 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2013 4470 m 2133 4500 l 2013 4530 l 2175 4530 l 2175 4470 l  cp clip
n 1800 4500 m 2160 4500 l gs col-1 s gr gr

% arrowhead
n 2013 4470 m 2133 4500 l 2013 4530 l 2013 4500 l 2013 4470 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2325 5703 m 2295 5823 l 2265 5703 l 2265 5865 l 2325 5865 l  cp clip
n 2295 4500 m 2295 5850 l gs col-1 s gr gr

% arrowhead
n 2325 5703 m 2295 5823 l 2265 5703 l 2295 5703 l 2325 5703 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1665 6705 m 2925 6705 l gs col-1 s gr 
% Polyline
n 1665 6435 m 2925 6435 l gs col-1 s gr 
% Polyline
n 1665 5850 m 2925 5850 l 2925 6975 l 1665 6975 l cp gs col-1 s gr 
% Polyline
n 2655 6075 m 2655 6975 l gs col-1 s gr 
% Polyline
n 1665 6075 m 2925 6075 l gs col-1 s gr 
% Polyline
n 2655 6435 m 2925 6705 l gs col-1 s gr 
% Polyline
n 2655 6705 m 2925 6435 l gs col-1 s gr 
% Polyline
n 2655 6705 m 2925 6975 l gs col-1 s gr 
% Polyline
n 2925 6705 m 2655 6975 l gs col-1 s gr 
% Polyline
n 3330 6705 m 4590 6705 l gs col-1 s gr 
% Polyline
n 3330 6435 m 4590 6435 l gs col-1 s gr 
% Polyline
n 3330 5850 m 4590 5850 l 4590 6975 l 3330 6975 l cp gs col-1 s gr 
% Polyline
n 4320 6075 m 4320 6975 l gs col-1 s gr 
% Polyline
n 3330 6075 m 4590 6075 l gs col-1 s gr 
% Polyline
n 4320 6435 m 4590 6705 l gs col-1 s gr 
% Polyline
n 4320 6705 m 4590 6435 l gs col-1 s gr 
% Polyline
n 4320 6705 m 4590 6975 l gs col-1 s gr 
% Polyline
n 4590 6705 m 4320 6975 l gs col-1 s gr 
% Polyline
gs  clippath
2013 1185 m 2133 1215 l 2013 1245 l 2175 1245 l 2175 1185 l  cp clip
n 1800 1215 m 2160 1215 l gs col-1 s gr gr

% arrowhead
n 2013 1185 m 2133 1215 l 2013 1245 l 2013 1215 l 2013 1185 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2325 2418 m 2295 2538 l 2265 2418 l 2265 2580 l 2325 2580 l  cp clip
n 2295 1215 m 2295 2565 l gs col-1 s gr gr

% arrowhead
n 2325 2418 m 2295 2538 l 2265 2418 l 2295 2418 l 2325 2418 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1665 3420 m 2925 3420 l gs col-1 s gr 
% Polyline
n 1665 3150 m 2925 3150 l gs col-1 s gr 
% Polyline
n 1665 2565 m 2925 2565 l 2925 3690 l 1665 3690 l cp gs col-1 s gr 
% Polyline
n 2655 2790 m 2655 3690 l gs col-1 s gr 
% Polyline
n 1665 2790 m 2925 2790 l gs col-1 s gr 
% Polyline
n 2655 3150 m 2925 3420 l gs col-1 s gr 
% Polyline
n 2655 3420 m 2925 3150 l gs col-1 s gr 
% Polyline
n 2655 3420 m 2925 3690 l gs col-1 s gr 
% Polyline
n 2925 3420 m 2655 3690 l gs col-1 s gr 
% Polyline
n 3330 3420 m 4590 3420 l gs col-1 s gr 
% Polyline
n 3330 3150 m 4590 3150 l gs col-1 s gr 
% Polyline
n 3330 2565 m 4590 2565 l 4590 3690 l 3330 3690 l cp gs col-1 s gr 
% Polyline
n 4320 2790 m 4320 3690 l gs col-1 s gr 
% Polyline
n 3330 2790 m 4590 2790 l gs col-1 s gr 
% Polyline
n 4320 3150 m 4590 3420 l gs col-1 s gr 
% Polyline
n 4320 3420 m 4590 3150 l gs col-1 s gr 
% Polyline
n 4320 3420 m 4590 3690 l gs col-1 s gr 
% Polyline
n 4590 3420 m 4320 3690 l gs col-1 s gr 
% Open spline
gs  clippath
3269 4798 m 3352 4890 l 3236 4848 l 3371 4938 l 3404 4888 l  cp clip
n 3060.0 4500.0 m 3082.5 4612.5 l
	3082.5 4612.5 3105.0 4725.0 3240.0 4815.0 DrawSplineSection
	3375.0 4905.0 l  gs col-1 s gr
 gr

% arrowhead
n 3269 4798 m 3352 4890 l 3236 4848 l 3253 4823 l 3269 4798 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4096 5786 m 3981 5833 l 4060 5738 l 3930 5835 l 3966 5883 l  cp clip
n 4185.0 5490.0 m 4162.5 5602.5 l
	4162.5 5602.5 4140.0 5715.0 4050.0 5782.5 DrawSplineSection
	3960.0 5850.0 l  gs col-1 s gr
 gr

% arrowhead
n 4096 5786 m 3981 5833 l 4060 5738 l 4078 5762 l 4096 5786 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3269 1513 m 3352 1605 l 3236 1563 l 3371 1653 l 3404 1603 l  cp clip
n 3060.0 1215.0 m 3082.5 1327.5 l
	3082.5 1327.5 3105.0 1440.0 3240.0 1530.0 DrawSplineSection
	3375.0 1620.0 l  gs col-1 s gr
 gr

% arrowhead
n 3269 1513 m 3352 1605 l 3236 1563 l 3253 1538 l 3269 1513 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
4096 2501 m 3981 2548 l 4060 2453 l 3930 2550 l 3966 2598 l  cp clip
n 4185.0 2205.0 m 4162.5 2317.5 l
	4162.5 2317.5 4140.0 2430.0 4050.0 2497.5 DrawSplineSection
	3960.0 2565.0 l  gs col-1 s gr
 gr

% arrowhead
n 4096 2501 m 3981 2548 l 4060 2453 l 4078 2477 l 4096 2501 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
2205 6300 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1980 6030 m
gs 1 -1 sc (Query \(B\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3870 6300 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3690 6030 m
gs 1 -1 sc (Query \(C\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
2205 3015 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1980 2745 m
gs 1 -1 sc (Query \(A\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3870 3015 m
gs 1 -1 sc  90.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3690 2745 m
gs 1 -1 sc (Query \(C\)) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1710 3330 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1710 3600 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 3330 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 3600 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 6615 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 6885 m
gs 1 -1 sc (intersectClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1710 6615 m
gs 1 -1 sc (unionClause) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1710 6885 m
gs 1 -1 sc (intersectClause) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 391 2309 a(Figure)11 b(3.13:)16 b(Data)c(structure)g(of)g
Fl(\()p Fk(A)g Fo([)f Fk(B)r Fl(\))p Fo(n)p Fk(C)16 b
Ft(after)c(transformation)f(to)h(DNF)273 2542 y Fo(\017)25
b Ft(T)n(ransform)14 b(the)g(ne)o(w)h Fp(oper)o(ator)g(tr)n(ee)g
Ft(into)f(DNF)h(\(disjuncti)o(v)o(e)f(normal)f(form\).)21
b(PostgreSQL)323 2602 y(does)f(not)f(pro)o(vide)h(an)o(y)g(function)f
(for)g(the)h(transformation)e(into)h(DNF)h(b)o(ut)g(it)f(pro)o(vides)h
(a)323 2662 y(function)14 b Fr(cnfify\(\))g Ft(that)h(performs)f(a)i
(transformation)e(into)g(CNF)i(\(conjuncti)o(v)o(e)e(normal)323
2721 y(form\).)g(So)e(we)g(can)h(easily)g(make)f(use)g(of)g(this)h
(function)e(when)i(we)f(e)o(xchange)h(e)o(v)o(ery)f Fr(OR)g
Ft(with)323 2781 y(an)17 b Fr(AND)f Ft(and)h(vice)g(v)o(ersa)h(before)e
(calling)h Fr(cnfify\(\))f Ft(as)h(we)g(did)g(already)g(in)g(the)f
Fp(parser)323 2841 y Ft(\(compare)11 b(\002gure)h(3.11)h(to)f(\002gure)
g(3.12\).)k(When)c Fr(cnfify\(\))g Ft(is)h(called)f(with)g(a)h(special)
g(\003ag,)323 2901 y(the)f Fr(removeAndFlag)g Ft(set)h(to)f
Fr(true)h Ft(it)f(returns)g(a)h(list)g(where)g(the)f(entries)h(can)g
(be)g(thought)323 2961 y(of)e(being)i(connected)f(together)g(by)g
Fr(ANDs)p Ft(,)g(so)h(the)f(e)o(xplicit)h Fr(AND)f Ft(nodes)g(are)h
(remo)o(v)o(ed.)323 3062 y(After)d Fr(cnfify\(\))h Ft(has)h(been)f
(called)h(we)f(normally)g(would)f(ha)o(v)o(e)i(to)g(e)o(xchange)g
Fr(OR)f Ft(and)g Fr(AND)323 3122 y Ft(nodes)16 b(again.)28
b(W)l(e)17 b(skip)g(this)g(step)f(by)h(simply)f(treating)g(e)o(v)o(ery)
g Fr(OR)h Ft(node)f(as)h(an)g Fr(AND)f Ft(node)323 3181
y(throughout)10 b(the)h(follo)o(wing)f(steps)i(\(remember)n(,)f(that)g
(there)h(are)f(no)g Fr(AND)h Ft(nodes)f(left)g(that)h(ha)o(v)o(e)323
3241 y(to)g(be)g(treated)g(as)h Fr(OR)f Ft(nodes)h(because)g(of)f(the)g
Fr(removeAndFlag)p Ft(\).)323 3342 y(Figure)e(3.13)i(sho)o(ws)h(what)e
(the)h(data)g(structure)f(looks)h(like)f(after)g(the)h(transformation)e
(to)h(DNF)323 3402 y(has)h(taken)g(place)h(for)e(the)i(follo)o(wing)e
(query:)p eop
%%Page: 108 108
108 107 bop 270 60 a Ft(108)57 b Fm(CHAPTER)14 b(3.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
454 234 y Fr(\(select)29 b(*)h(from)g(A)484 294 y(union)484
354 y(select)f(*)h(from)g(B\))484 413 y(except)484 473
y(select)f(*)h(from)g(C;)345 589 y Fo(\017)25 b Ft(F)o(or)10
b(e)o(v)o(ery)h(entry)g(of)g(the)g(list)g(returned)g(by)g
Fr(cnfify\(\))f Ft(\(i.e.)16 b(for)10 b(e)o(v)o(ery)h
Fp(oper)o(ator)h(tr)n(ee)g Ft(which)395 648 y(may)e(only)g(contain)h
Fr(OR)f Ft(and)h Fr(NOT)f Ft(operator)g(nodes)h(and)f
Fr(Query)g Ft(nodes)h(as)g(lea)o(v)o(es\))g(contained)395
708 y(in)h(the)g Fr(union)p 672 708 15 2 v 17 w(list)g
Ft(perform)f(the)i(follo)o(wing)e(steps:)454 806 y Fn(\226)25
b Ft(Check)15 b(if)g(the)g Fp(tar)n(getlists)f Ft(of)h(all)g
Fr(Query)f Ft(nodes)h(appearing)g(are)f(compatible)h(\(i.e.)23
b(all)504 866 y Fp(tar)n(getlists)13 b Ft(ha)o(v)o(e)h(the)f(same)h
(number)e(of)h(attrib)o(utes)g(and)g(the)g(corresponding)g(attrib)o
(utes)504 926 y(are)f(of)g(the)h(same)f(type\))454 1004
y Fn(\226)25 b Ft(There)13 b(must)f(be)h(at)g(least)g(one)f(positi)o(v)
o(e)h Fr(OR)f Ft(node)h(\(i.e.)j(at)d(least)g(one)f Fr(OR)h
Ft(node)f(which)h(is)504 1064 y(not)h(preceded)g(by)f(a)h
Fr(NOT)g Ft(node\).)20 b(Create)14 b(a)g(list)g(of)g(all)f
Fr(Query)h Ft(nodes)g(\(or)f(of)h Fr(Query)504 1123 y
Ft(nodes)f(preceded)f(by)h Fr(NOT)f Ft(nodes)h(if)f Fr(OR)29
b(NOT)13 b Ft(is)f(found\))g(with)g(the)g(non)h(ne)o(gated)f(node)504
1183 y(\002rst)g(using)g(the)h(function)e Fr(create)p
1149 1183 V 18 w(list\(\))g Ft(described)i(belo)o(w)m(.)454
1261 y Fn(\226)25 b Ft(The)19 b(\002rst)f(\(non)f(ne)o(gated\))h(node)g
(of)g(the)g(list)g(will)g(be)g(the)g(topmost)g Fr(Query)f
Ft(node)i(of)504 1321 y(the)g(current)f Fp(union)h Ft(operand.)36
b(F)o(or)18 b(all)h(other)g(nodes)g(found)g(in)g(the)g(list)g(add)g(an)
g Fr(IN)504 1381 y Ft(subselect)14 b(\()p Fr(NOT)29 b(IN)14
b Ft(subselect)g(if)f(the)g Fr(Query)g Ft(node)h(is)g(preceded)f(by)g
(a)h Fr(NOT)p Ft(\))f(to)g(the)504 1440 y Fr(where)j
Ft(quali\002cation)g(of)f(the)i(topmost)f(node.)28 b(Adding)15
b(a)i(subselect)g(to)f(the)h Fr(where)504 1500 y Ft(quali\002cation)12
b(is)g(done)h(by)f(logically)g Fr(AND)p Ft(ing)f(it)i(to)f(the)g
(original)g(quali\002cation.)454 1578 y Fn(\226)25 b
Ft(Append)16 b(the)f Fr(Query)g Ft(node)h(setup)g(in)f(the)h(last)g
(steps)g(to)f(a)h(list)g(which)f(is)h(hold)g(by)f(the)504
1638 y(pointer)d Fr(union)p 811 1638 V 17 w(list)p Ft(.)345
1736 y Fo(\017)25 b Ft(T)l(ake)17 b(the)f(\002rst)h(node)g(of)f
Fr(union)p 1004 1736 V 18 w(list)g Ft(as)i(the)e(ne)o(w)h(topmost)g
(node)g(of)f(the)h(whole)g(query)395 1796 y(and)11 b(attach)h(the)f
(rest)h(of)f(the)g(list)h(to)f(the)h(\002eld)f Fr(unionClause)f
Ft(of)h(this)h(topmost)f(node.)k(Since)395 1856 y(the)f(ne)o(w)g
(topmost)g(node)h(might)f(dif)o(fer)f(from)g(the)i(original)e(one)i
(\(i.e.)22 b(from)13 b(the)i(node)f(which)395 1915 y(was)h(topmost)g
(when)g(we)g(entered)g(the)g Fp(r)n(e)o(write)i(stage)p
Ft(\))d(we)h(ha)o(v)o(e)h(to)f(attach)g(the)g(\002elds)g(sa)o(v)o(ed)
395 1975 y(in)h(the)h(\002rst)g(step)g(to)g(the)g(ne)o(w)g(topmost)f
(node)h(\(i.e.)30 b(the)17 b Fr(sortClause)p Ft(,)h Fr(targetList)p
Ft(,)395 2035 y Fr(unionFlag)p Ft(,)11 b(etc.\).)345
2133 y Fo(\017)25 b Ft(Hand)16 b(the)h(ne)o(w)g(topmost)g
Fr(Query)f Ft(node)h(back.)29 b(No)o(w)17 b(the)g(normal)f
Fp(query)h(r)n(e)o(writing)h Ft(takes)395 2193 y(place)12
b(\(in)f(order)g(to)h(handle)g(vie)o(ws)g(if)f(present\))h(and)f(then)h
(the)g Fp(planner/optimizer)g Ft(and)g Fp(e)o(xecu-)395
2252 y(tor)g Ft(functions)f(are)g(called)h(to)g(get)g(a)g(result.)j
(There)d(ha)o(v)o(e)g(no)g(changes)g(been)g(made)g(to)f(the)h(code)395
2312 y(of)f(these)i(stages.)270 2408 y(Figure)f(3.14)g(sho)o(ws)h(the)f
(re)o(written)f(data)i(structure)e(of)h(the)h(query:)360
2505 y Fr(select)29 b(C1,)g(C2)h(from)g(A)360 2565 y(intersect)360
2624 y(select)f(C1,)g(C3)h(from)g(C;)270 2721 y Ft(against)11
b(the)g(tables)h(de\002ned)f(in)g(e)o(xample)g(3.4.)16
b(The)c(re)o(written)d(data)j(structure)e(represents)i(the)f(query:)330
2817 y Fr(select)29 b(C1,)h(C2)f(form)h(A)330 2877 y(where)f(\(C1,)h
(C2\))f(in)509 2936 y(\(select)g(C1,C3)h(from)f(C\);)270
3033 y Ft(The)15 b(\002eld)e Fr(lefttree)h Ft(of)g(the)g
Fr(Sublink)f Ft(node)h(points)g(to)g(a)g(list)h(where)e(e)o(v)o(ery)h
(entry)g(points)g(to)g(a)270 3093 y Fr(VAR)e Ft(node)g(of)g(the)g
Fp(tar)n(getlist)g Ft(of)g(the)h(topmost)e(node)i(\(node)f(A\).)g(The)h
(\002eld)f Fr(oper)g Ft(of)g(the)g Fr(Sublink)270 3152
y Ft(node)i(points)h(to)f(a)h(list)f(holding)g(a)h(pointer)e(to)i(an)f
Fr(Expr)g Ft(node)h(for)e(e)o(v)o(ery)h(attrib)o(ute)g(of)g(the)g
(topmost)270 3212 y Fp(tar)n(getlist)p Ft(.)k(Ev)o(ery)13
b Fr(Expr)g Ft(node)g(is)h(used)f(to)g(compare)g(a)g
Fr(VAR)g Ft(node)g(of)g(the)g(topmost)g Fp(tar)n(getlist)f
Ft(with)270 3272 y(the)17 b(corresponding)f Fr(VAR)g
Ft(node)h(of)f(the)h(subselect')m(s)h Fp(tar)n(getlist)p
Ft(.)28 b(So)17 b(the)g(\002rst)f(ar)o(gument)g(of)g(e)o(v)o(ery)270
3332 y Fr(Expr)c Ft(node)h(points)g(to)g(a)g Fr(VAR)f
Ft(node)h(of)f(the)h(topmost)g Fp(tar)n(getlist)f Ft(and)h(the)g
(second)g(ar)o(gument)f(points)270 3391 y(to)g(the)h(corresponding)e
Fr(VAR)h Ft(node)g(of)g(the)h(subselect')m(s)g Fp(tar)n(getlist)p
Ft(.)p eop
%%Page: 109 109
109 108 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)324
b Ft(109)298 3216 y @beginspecial 136 @llx 94 @lly 476
@urx 697 @ury 3400 @rwi @setspecial
%%BeginDocument: figures/union_operand.ps
%Magnification: 1.05
/$F2psDict 200 dict def
$F2psDict begin
$F2psDict /mtrx matrix put
/col-1 {0 setgray} bind def
/col0 {0.000 0.000 0.000 srgb} bind def
/col1 {0.000 0.000 1.000 srgb} bind def
/col2 {0.000 1.000 0.000 srgb} bind def
/col3 {0.000 1.000 1.000 srgb} bind def
/col4 {1.000 0.000 0.000 srgb} bind def
/col5 {1.000 0.000 1.000 srgb} bind def
/col6 {1.000 1.000 0.000 srgb} bind def
/col7 {1.000 1.000 1.000 srgb} bind def
/col8 {0.000 0.000 0.560 srgb} bind def
/col9 {0.000 0.000 0.690 srgb} bind def
/col10 {0.000 0.000 0.820 srgb} bind def
/col11 {0.530 0.810 1.000 srgb} bind def
/col12 {0.000 0.560 0.000 srgb} bind def
/col13 {0.000 0.690 0.000 srgb} bind def
/col14 {0.000 0.820 0.000 srgb} bind def
/col15 {0.000 0.560 0.560 srgb} bind def
/col16 {0.000 0.690 0.690 srgb} bind def
/col17 {0.000 0.820 0.820 srgb} bind def
/col18 {0.560 0.000 0.000 srgb} bind def
/col19 {0.690 0.000 0.000 srgb} bind def
/col20 {0.820 0.000 0.000 srgb} bind def
/col21 {0.560 0.000 0.560 srgb} bind def
/col22 {0.690 0.000 0.690 srgb} bind def
/col23 {0.820 0.000 0.820 srgb} bind def
/col24 {0.500 0.190 0.000 srgb} bind def
/col25 {0.630 0.250 0.000 srgb} bind def
/col26 {0.750 0.380 0.000 srgb} bind def
/col27 {1.000 0.500 0.500 srgb} bind def
/col28 {1.000 0.630 0.630 srgb} bind def
/col29 {1.000 0.750 0.750 srgb} bind def
/col30 {1.000 0.880 0.880 srgb} bind def
/col31 {1.000 0.840 0.000 srgb} bind def

end
save
126.0 696.5 translate
1 -1 scale

/cp {closepath} bind def
/ef {eofill} bind def
/gr {grestore} bind def
/gs {gsave} bind def
/sa {save} bind def
/rs {restore} bind def
/l {lineto} bind def
/m {moveto} bind def
/rm {rmoveto} bind def
/n {newpath} bind def
/s {stroke} bind def
/sh {show} bind def
/slc {setlinecap} bind def
/slj {setlinejoin} bind def
/slw {setlinewidth} bind def
/srgb {setrgbcolor} bind def
/rot {rotate} bind def
/sc {scale} bind def
/sd {setdash} bind def
/ff {findfont} bind def
/sf {setfont} bind def
/scf {scalefont} bind def
/sw {stringwidth} bind def
/tr {translate} bind def
/tnt {dup dup currentrgbcolor
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add
  4 -2 roll dup 1 exch sub 3 -1 roll mul add srgb}
  bind def
/shd {dup dup currentrgbcolor 4 -2 roll mul 4 -2 roll mul
  4 -2 roll mul srgb} bind def
 /DrawSplineSection {
	/y3 exch def
	/x3 exch def
	/y2 exch def
	/x2 exch def
	/y1 exch def
	/x1 exch def
	/xa x1 x2 x1 sub 0.666667 mul add def
	/ya y1 y2 y1 sub 0.666667 mul add def
	/xb x3 x2 x3 sub 0.666667 mul add def
	/yb y3 y2 y3 sub 0.666667 mul add def
	x1 y1 lineto
	xa ya xb yb x3 y3 curveto
	} def

/$F2psBegin {$F2psDict begin /$F2psEnteredState save def} def
/$F2psEnd {$F2psEnteredState restore end} def

$F2psBegin
10 setmiterlimit
n 0 792 m 0 0 l 612 0 l 612 792 l cp clip
 0.06299 0.06299 sc
7.500 slw
% Polyline
n 180 3780 m 1170 3780 l gs col-1 s gr 
% Polyline
n 180 4050 m 1170 4050 l gs col-1 s gr 
% Polyline
n 180 4320 m 1170 4320 l gs col-1 s gr 
% Polyline
n 180 4590 m 1170 4590 l gs col-1 s gr 
% Polyline
n 900 3780 m 900 5040 l gs col-1 s gr 
% Polyline
n 180 3555 m 1170 3555 l 1170 5040 l 180 5040 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
450 3735 m
gs 1 -1 sc (Sublink) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 4725 m
gs 1 -1 sc  270.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 4500 m
gs 1 -1 sc (subselect) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 4230 m
gs 1 -1 sc (oper) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 3960 m
gs 1 -1 sc (lefthand) col-1 sh gr
% Polyline
n 3195 3780 m 3735 3780 l 3735 4050 l 3195 4050 l cp gs col-1 s gr 
% Polyline
n 3465 3780 m 3465 4050 l gs col-1 s gr 
% Polyline
n 3465 3780 m 3735 4050 l gs col-1 s gr 
% Polyline
n 3735 3780 m 3465 4050 l gs col-1 s gr 
% Polyline
n 1710 3780 m 2250 3780 l 2250 4050 l 1710 4050 l cp gs col-1 s gr 
% Polyline
n 1980 3780 m 1980 4050 l gs col-1 s gr 
% Polyline
gs  clippath
3048 3885 m 3168 3915 l 3048 3945 l 3210 3945 l 3210 3885 l  cp clip
n 2115 3915 m 3195 3915 l gs col-1 s gr gr

% arrowhead
n 3048 3885 m 3168 3915 l 3048 3945 l 3048 3915 l 3048 3885 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3195 4140 m 3735 4140 l 3735 4410 l 3195 4410 l cp gs col-1 s gr 
% Polyline
n 3465 4140 m 3465 4410 l gs col-1 s gr 
% Polyline
n 3465 4140 m 3735 4410 l gs col-1 s gr 
% Polyline
n 3735 4140 m 3465 4410 l gs col-1 s gr 
% Polyline
n 1710 4140 m 2250 4140 l 2250 4410 l 1710 4410 l cp gs col-1 s gr 
% Polyline
n 1980 4140 m 1980 4410 l gs col-1 s gr 
% Polyline
gs  clippath
3048 4245 m 3168 4275 l 3048 4305 l 3210 4305 l 3210 4245 l  cp clip
n 2115 4275 m 3195 4275 l gs col-1 s gr gr

% arrowhead
n 3048 4245 m 3168 4275 l 3048 4305 l 3048 4275 l 3048 4245 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1395 5265 m 2295 5265 l gs col-1 s gr 
% Polyline
n 1395 5535 m 2295 5535 l gs col-1 s gr 
% Polyline
n 1395 5040 m 2295 5040 l 2295 5805 l 1395 5805 l cp gs col-1 s gr 
% Polyline
n 2025 5535 m 2025 5805 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1710 5220 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1485 5445 m
gs 1 -1 sc (opType: '=') col-1 sh gr
/Times-Roman ff 150.00 scf sf
1485 5715 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 2520 5535 m 3060 5535 l 3060 5805 l 2520 5805 l cp gs col-1 s gr 
% Polyline
n 2790 5535 m 2790 5805 l gs col-1 s gr 
% Polyline
n 3285 5535 m 3825 5535 l 3825 5805 l 3285 5805 l cp gs col-1 s gr 
% Polyline
n 3555 5535 m 3555 5805 l gs col-1 s gr 
% Polyline
n 3555 5535 m 3825 5805 l gs col-1 s gr 
% Polyline
n 3825 5535 m 3555 5805 l gs col-1 s gr 
% Polyline
gs  clippath
3138 5640 m 3258 5670 l 3138 5700 l 3300 5700 l 3300 5640 l  cp clip
n 2925 5670 m 3285 5670 l gs col-1 s gr gr

% arrowhead
n 3138 5640 m 3258 5670 l 3138 5700 l 3138 5670 l 3138 5640 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
2373 5640 m 2493 5670 l 2373 5700 l 2535 5700 l 2535 5640 l  cp clip
n 2160 5670 m 2520 5670 l gs col-1 s gr gr

% arrowhead
n 2373 5640 m 2493 5670 l 2373 5700 l 2373 5670 l 2373 5640 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3105 4815 m 4005 4815 l gs col-1 s gr 
% Polyline
n 3105 5085 m 4005 5085 l gs col-1 s gr 
% Polyline
n 3105 4590 m 4005 4590 l 4005 5355 l 3105 5355 l cp gs col-1 s gr 
% Polyline
n 3735 5085 m 3735 5355 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3420 4770 m
gs 1 -1 sc (Expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3195 4995 m
gs 1 -1 sc (opType: '=') col-1 sh gr
/Times-Roman ff 150.00 scf sf
3195 5265 m
gs 1 -1 sc (args) col-1 sh gr
% Polyline
n 4230 5085 m 4770 5085 l 4770 5355 l 4230 5355 l cp gs col-1 s gr 
% Polyline
n 4500 5085 m 4500 5355 l gs col-1 s gr 
% Polyline
n 4995 5085 m 5535 5085 l 5535 5355 l 4995 5355 l cp gs col-1 s gr 
% Polyline
n 5265 5085 m 5265 5355 l gs col-1 s gr 
% Polyline
n 5265 5085 m 5535 5355 l gs col-1 s gr 
% Polyline
n 5535 5085 m 5265 5355 l gs col-1 s gr 
% Polyline
n 3600 0 m 4140 0 l 4140 270 l 3600 270 l cp gs col-1 s gr 
% Polyline
n 3870 0 m 3870 270 l gs col-1 s gr 
% Polyline
n 3870 0 m 4140 270 l gs col-1 s gr 
% Polyline
n 4140 0 m 3870 270 l gs col-1 s gr 
% Polyline
n 3285 495 m 4185 495 l 4185 990 l 3285 990 l cp gs col-1 s gr 
% Polyline
n 3285 720 m 4185 720 l gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3375 900 m
gs 1 -1 sc (relname: "A") col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 675 m
gs 1 -1 sc (RTE) col-1 sh gr
% Polyline
n 1395 315 m 1935 315 l 1935 585 l 1395 585 l cp gs col-1 s gr 
% Polyline
n 1665 315 m 1665 585 l gs col-1 s gr 
% Polyline
n 2160 315 m 2700 315 l 2700 585 l 2160 585 l cp gs col-1 s gr 
% Polyline
n 2430 315 m 2430 585 l gs col-1 s gr 
% Polyline
n 2430 315 m 2700 585 l gs col-1 s gr 
% Polyline
n 2700 315 m 2430 585 l gs col-1 s gr 
% Polyline
gs  clippath
2013 420 m 2133 450 l 2013 480 l 2175 480 l 2175 420 l  cp clip
n 1800 450 m 2160 450 l gs col-1 s gr gr

% arrowhead
n 2013 420 m 2133 450 l 2013 480 l 2013 450 l 2013 420 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1440 2340 m 2340 2340 l gs col-1 s gr 
% Polyline
n 1440 2115 m 2340 2115 l 2340 2610 l 1440 2610 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1665 2295 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1530 2520 m
gs 1 -1 sc (resname: C1) col-1 sh gr
% Polyline
n 2925 2340 m 3825 2340 l gs col-1 s gr 
% Polyline
n 2925 2115 m 3825 2115 l 3825 2610 l 2925 2610 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
3150 2295 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 2520 m
gs 1 -1 sc (resname: C2) col-1 sh gr
% Polyline
n 3600 5985 m 4140 5985 l 4140 6255 l 3600 6255 l cp gs col-1 s gr 
% Polyline
n 3870 5985 m 3870 6255 l gs col-1 s gr 
% Polyline
n 3870 5985 m 4140 6255 l gs col-1 s gr 
% Polyline
n 4140 5985 m 3870 6255 l gs col-1 s gr 
% Polyline
n 1395 6300 m 1935 6300 l 1935 6570 l 1395 6570 l cp gs col-1 s gr 
% Polyline
n 1665 6300 m 1665 6570 l gs col-1 s gr 
% Polyline
n 2160 6300 m 2700 6300 l 2700 6570 l 2160 6570 l cp gs col-1 s gr 
% Polyline
n 2430 6300 m 2430 6570 l gs col-1 s gr 
% Polyline
n 2430 6300 m 2700 6570 l gs col-1 s gr 
% Polyline
n 2700 6300 m 2430 6570 l gs col-1 s gr 
% Polyline
gs  clippath
2013 6405 m 2133 6435 l 2013 6465 l 2175 6465 l 2175 6405 l  cp clip
n 1800 6435 m 2160 6435 l gs col-1 s gr gr

% arrowhead
n 2013 6405 m 2133 6435 l 2013 6465 l 2013 6435 l 2013 6405 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 1440 8325 m 2340 8325 l gs col-1 s gr 
% Polyline
n 1440 8100 m 2340 8100 l 2340 8595 l 1440 8595 l cp gs col-1 s gr 
/Times-Roman ff 150.00 scf sf
1665 8280 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1530 8505 m
gs 1 -1 sc (resname: C1) col-1 sh gr
% Polyline
n 180 225 m 1170 225 l gs col-1 s gr 
% Polyline
n 180 495 m 1170 495 l gs col-1 s gr 
% Polyline
n 180 765 m 1170 765 l gs col-1 s gr 
% Polyline
n 180 1035 m 1170 1035 l gs col-1 s gr 
% Polyline
n 900 225 m 900 1440 l gs col-1 s gr 
% Polyline
n 180 0 m 1170 0 l 1170 1440 l 180 1440 l cp gs col-1 s gr 
% Polyline
gs  clippath
3300 3702 m 3330 3582 l 3360 3702 l 3360 3540 l 3300 3540 l  cp clip
n 3330 3915 m 3330 3555 l gs col-1 s gr gr

% arrowhead
n 3300 3702 m 3330 3582 l 3360 3702 l 3330 3702 l 3300 3702 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1815 3702 m 1845 3582 l 1875 3702 l 1875 3540 l 1815 3540 l  cp clip
n 1845 3915 m 1845 3555 l gs col-1 s gr gr

% arrowhead
n 1815 3702 m 1845 3582 l 1875 3702 l 1845 3702 l 1815 3702 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1875 4893 m 1845 5013 l 1815 4893 l 1815 5055 l 1875 5055 l  cp clip
n 1845 4275 m 1845 5040 l gs col-1 s gr gr

% arrowhead
n 1875 4893 m 1845 5013 l 1815 4893 l 1845 4893 l 1875 4893 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
1563 3885 m 1683 3915 l 1563 3945 l 1725 3945 l 1725 3885 l  cp clip
n 1035 3915 m 1710 3915 l gs col-1 s gr gr

% arrowhead
n 1563 3885 m 1683 3915 l 1563 3945 l 1563 3915 l 1563 3885 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4848 5190 m 4968 5220 l 4848 5250 l 5010 5250 l 5010 5190 l  cp clip
n 4635 5220 m 4995 5220 l gs col-1 s gr gr

% arrowhead
n 4848 5190 m 4968 5220 l 4848 5250 l 4848 5220 l 4848 5190 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
4083 5190 m 4203 5220 l 4083 5250 l 4245 5250 l 4245 5190 l  cp clip
n 3870 5220 m 4230 5220 l gs col-1 s gr gr

% arrowhead
n 4083 5190 m 4203 5220 l 4083 5250 l 4083 5220 l 4083 5190 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
gs  clippath
3765 348 m 3735 468 l 3705 348 l 3705 510 l 3765 510 l  cp clip
n 3735 135 m 3735 495 l gs col-1 s gr gr

% arrowhead
n 3765 348 m 3735 468 l 3705 348 l 3735 348 l 3765 348 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3555 1395 m 3555 1935 l gs col-1 s gr 
% Polyline
n 2925 1395 m 3825 1395 l gs col-1 s gr 
% Polyline
n 2925 1665 m 3825 1665 l gs col-1 s gr 
% Polyline
n 2925 1170 m 3825 1170 l 3825 1935 l 2925 1935 l cp gs col-1 s gr 
% Polyline
n 2070 1395 m 2070 1935 l gs col-1 s gr 
% Polyline
n 1440 1395 m 2340 1395 l gs col-1 s gr 
% Polyline
n 1440 1665 m 2340 1665 l gs col-1 s gr 
% Polyline
n 1440 1170 m 2340 1170 l 2340 1935 l 1440 1935 l cp gs col-1 s gr 
% Polyline
n 180 6210 m 1170 6210 l gs col-1 s gr 
% Polyline
n 180 6480 m 1170 6480 l gs col-1 s gr 
% Polyline
n 180 6750 m 1170 6750 l gs col-1 s gr 
% Polyline
n 180 7020 m 1170 7020 l gs col-1 s gr 
% Polyline
n 900 6210 m 900 7425 l gs col-1 s gr 
% Polyline
n 180 5985 m 1170 5985 l 1170 7425 l 180 7425 l cp gs col-1 s gr 
% Polyline
gs  clippath
3765 6333 m 3735 6453 l 3705 6333 l 3705 6495 l 3765 6495 l  cp clip
n 3735 6120 m 3735 6480 l gs col-1 s gr gr

% arrowhead
n 3765 6333 m 3735 6453 l 3705 6333 l 3735 6333 l 3765 6333 l  cp gs 0.00 setgray ef gr  col-1 s
% Polyline
n 3555 7380 m 3555 7920 l gs col-1 s gr 
% Polyline
n 2925 7380 m 3825 7380 l gs col-1 s gr 
% Polyline
n 2925 7650 m 3825 7650 l gs col-1 s gr 
% Polyline
n 2925 7155 m 3825 7155 l 3825 7920 l 2925 7920 l cp gs col-1 s gr 
% Polyline
n 2070 7380 m 2070 7920 l gs col-1 s gr 
% Polyline
n 1440 7380 m 2340 7380 l gs col-1 s gr 
% Polyline
n 1440 7650 m 2340 7650 l gs col-1 s gr 
% Polyline
n 1440 7155 m 2340 7155 l 2340 7920 l 1440 7920 l cp gs col-1 s gr 
% Polyline
n 2925 8325 m 3825 8325 l gs col-1 s gr 
% Polyline
n 2925 8100 m 3825 8100 l 3825 8595 l 2925 8595 l cp gs col-1 s gr 
% Polyline
n 3285 6480 m 4185 6480 l 4185 6975 l 3285 6975 l cp gs col-1 s gr 
% Polyline
n 3285 6705 m 4185 6705 l gs col-1 s gr 
% Polyline
n 1485 3015 m 2295 3015 l gs col-1 s gr 
% Polyline
n 1485 3285 m 2295 3285 l gs col-1 s gr 
% Polyline
n 1485 2790 m 2295 2790 l 2295 3555 l 1485 3555 l cp gs col-1 s gr 
% Polyline
n 2970 3015 m 3780 3015 l gs col-1 s gr 
% Polyline
n 2970 3285 m 3780 3285 l gs col-1 s gr 
% Polyline
n 2970 2790 m 3780 2790 l 3780 3555 l 2970 3555 l cp gs col-1 s gr 
% Polyline
n 1485 9000 m 2295 9000 l gs col-1 s gr 
% Polyline
n 1485 9270 m 2295 9270 l gs col-1 s gr 
% Polyline
n 1485 8775 m 2295 8775 l 2295 9540 l 1485 9540 l cp gs col-1 s gr 
% Polyline
n 2970 9000 m 3780 9000 l gs col-1 s gr 
% Polyline
n 2970 9270 m 3780 9270 l gs col-1 s gr 
% Polyline
n 2970 8775 m 3780 8775 l 3780 9540 l 2970 9540 l cp gs col-1 s gr 
% Open spline
gs  clippath
2363 3284 m 2311 3171 l 2410 3246 l 2309 3120 l 2262 3157 l  cp clip
n 2655.0 5670.0 m 2655.0 4635.0 l
	2655.0 4635.0 2655.0 3600.0 2475.0 3375.0 DrawSplineSection
	2295.0 3150.0 l  gs col-1 s gr
 gr

% arrowhead
n 2363 3284 m 2311 3171 l 2410 3246 l 2387 3265 l 2363 3284 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3878 3263 m 3801 3166 l 3915 3216 l 3786 3117 l 3750 3165 l  cp clip
n 4365.0 5220.0 m 4365.0 4410.0 l
	4365.0 4410.0 4365.0 3600.0 4072.5 3375.0 DrawSplineSection
	3780.0 3150.0 l  gs col-1 s gr
 gr

% arrowhead
n 3878 3263 m 3801 3166 l 3915 3216 l 3897 3240 l 3878 3263 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1577 4206 m 1684 4267 l 1560 4263 l 1716 4308 l 1733 4250 l  cp clip
n 1035.0 4185.0 m 1215.0 4185.0 l
	1215.0 4185.0 1395.0 4185.0 1552.5 4230.0 DrawSplineSection
	1710.0 4275.0 l  gs col-1 s gr
 gr

% arrowhead
n 1577 4206 m 1684 4267 l 1560 4263 l 1569 4235 l 1577 4206 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3455 4478 m 3533 4573 l 3419 4526 l 3549 4623 l 3585 4575 l  cp clip
n 3330.0 4275.0 m 3352.5 4365.0 l
	3352.5 4365.0 3375.0 4455.0 3465.0 4522.5 DrawSplineSection
	3555.0 4590.0 l  gs col-1 s gr
 gr

% arrowhead
n 3455 4478 m 3533 4573 l 3419 4526 l 3437 4502 l 3455 4478 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
711 3409 m 676 3528 l 651 3407 l 644 3569 l 704 3571 l  cp clip
n 1016.0 890.0 m 1151.0 912.5 l
	1151.0 912.5 1286.0 935.0 1286.0 1407.5 DrawSplineSection
	1286.0 1407.5 1286.0 1880.0 993.5 2420.0 DrawSplineSection
	993.5 2420.0 701.0 2960.0 688.0 3257.5 DrawSplineSection
	675.0 3555.0 l  gs col-1 s gr
 gr

% arrowhead
n 711 3409 m 676 3528 l 651 3407 l 681 3408 l 711 3409 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3453 105 m 3573 135 l 3453 165 l 3615 165 l 3615 105 l  cp clip
n 1035.0 360.0 m 1215.0 270.0 l
	1215.0 270.0 1395.0 180.0 1912.5 157.5 DrawSplineSection
	1912.5 157.5 2430.0 135.0 3015.0 135.0 DrawSplineSection
	3600.0 135.0 l  gs col-1 s gr
 gr

% arrowhead
n 3453 105 m 3573 135 l 3453 165 l 3453 135 l 3453 105 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1270 533 m 1375 469 l 1312 575 l 1427 461 l 1384 418 l  cp clip
n 1035.0 630.0 m 1147.5 607.5 l
	1147.5 607.5 1260.0 585.0 1327.5 517.5 DrawSplineSection
	1395.0 450.0 l  gs col-1 s gr
 gr

% arrowhead
n 1270 533 m 1375 469 l 1312 575 l 1291 554 l 1270 533 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1807 1045 m 1870 1150 l 1765 1087 l 1879 1202 l 1922 1159 l  cp clip
n 1530.0 450.0 m 1552.5 652.5 l
	1552.5 652.5 1575.0 855.0 1732.5 1012.5 DrawSplineSection
	1890.0 1170.0 l  gs col-1 s gr
 gr

% arrowhead
n 1807 1045 m 1870 1150 l 1765 1087 l 1786 1066 l 1807 1045 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3262 1071 m 3351 1156 l 3232 1123 l 3373 1203 l 3403 1151 l  cp clip
n 2295.0 450.0 m 2362.5 697.5 l
	2362.5 697.5 2430.0 945.0 2745.0 967.5 DrawSplineSection
	2745.0 967.5 3060.0 990.0 3217.5 1080.0 DrawSplineSection
	3375.0 1170.0 l  gs col-1 s gr
 gr

% arrowhead
n 3262 1071 m 3351 1156 l 3232 1123 l 3247 1097 l 3262 1071 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2035 2076 m 1914 2102 l 2008 2022 l 1863 2095 l 1890 2149 l  cp clip
n 2205.0 1530.0 m 2362.5 1530.0 l
	2362.5 1530.0 2520.0 1530.0 2520.0 1777.5 DrawSplineSection
	2520.0 1777.5 2520.0 2025.0 2295.0 2025.0 DrawSplineSection
	2295.0 2025.0 2070.0 2025.0 1980.0 2070.0 DrawSplineSection
	1890.0 2115.0 l  gs col-1 s gr
 gr

% arrowhead
n 2035 2076 m 1914 2102 l 2008 2022 l 2021 2049 l 2035 2076 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2029 2733 m 1912 2775 l 1996 2683 l 1861 2773 l 1894 2823 l  cp clip
n 2205.0 1800.0 m 2407.5 1800.0 l
	2407.5 1800.0 2610.0 1800.0 2610.0 2047.5 DrawSplineSection
	2610.0 2047.5 2610.0 2295.0 2610.0 2497.5 DrawSplineSection
	2610.0 2497.5 2610.0 2700.0 2317.5 2700.0 DrawSplineSection
	2317.5 2700.0 2025.0 2700.0 1957.5 2745.0 DrawSplineSection
	1890.0 2790.0 l  gs col-1 s gr
 gr

% arrowhead
n 2029 2733 m 1912 2775 l 1996 2683 l 2012 2708 l 2029 2733 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3520 2751 m 3399 2777 l 3493 2697 l 3348 2770 l 3375 2824 l  cp clip
n 3690.0 1800.0 m 3892.5 1800.0 l
	3892.5 1800.0 4095.0 1800.0 4095.0 2047.5 DrawSplineSection
	4095.0 2047.5 4095.0 2295.0 4095.0 2497.5 DrawSplineSection
	4095.0 2497.5 4095.0 2700.0 3825.0 2700.0 DrawSplineSection
	3825.0 2700.0 3555.0 2700.0 3465.0 2745.0 DrawSplineSection
	3375.0 2790.0 l  gs col-1 s gr
 gr

% arrowhead
n 3520 2751 m 3399 2777 l 3493 2697 l 3506 2724 l 3520 2751 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3520 2076 m 3399 2102 l 3493 2022 l 3348 2095 l 3375 2149 l  cp clip
n 3690.0 1530.0 m 3847.5 1530.0 l
	3847.5 1530.0 4005.0 1530.0 4005.0 1777.5 DrawSplineSection
	4005.0 1777.5 4005.0 2025.0 3780.0 2025.0 DrawSplineSection
	3780.0 2025.0 3555.0 2025.0 3465.0 2070.0 DrawSplineSection
	3375.0 2115.0 l  gs col-1 s gr
 gr

% arrowhead
n 3520 2076 m 3399 2102 l 3493 2022 l 3506 2049 l 3520 2076 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3453 6090 m 3573 6120 l 3453 6150 l 3615 6150 l 3615 6090 l  cp clip
n 1035.0 6345.0 m 1215.0 6255.0 l
	1215.0 6255.0 1395.0 6165.0 1912.5 6142.5 DrawSplineSection
	1912.5 6142.5 2430.0 6120.0 3015.0 6120.0 DrawSplineSection
	3600.0 6120.0 l  gs col-1 s gr
 gr

% arrowhead
n 3453 6090 m 3573 6120 l 3453 6150 l 3453 6120 l 3453 6090 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1270 6518 m 1375 6454 l 1312 6560 l 1427 6446 l 1384 6403 l  cp clip
n 1035.0 6615.0 m 1147.5 6592.5 l
	1147.5 6592.5 1260.0 6570.0 1327.5 6502.5 DrawSplineSection
	1395.0 6435.0 l  gs col-1 s gr
 gr

% arrowhead
n 1270 6518 m 1375 6454 l 1312 6560 l 1291 6539 l 1270 6518 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
1807 7030 m 1870 7135 l 1765 7072 l 1879 7187 l 1922 7144 l  cp clip
n 1530.0 6435.0 m 1552.5 6637.5 l
	1552.5 6637.5 1575.0 6840.0 1732.5 6997.5 DrawSplineSection
	1890.0 7155.0 l  gs col-1 s gr
 gr

% arrowhead
n 1807 7030 m 1870 7135 l 1765 7072 l 1786 7051 l 1807 7030 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3262 7056 m 3351 7141 l 3232 7108 l 3373 7188 l 3403 7136 l  cp clip
n 2295.0 6435.0 m 2362.5 6682.5 l
	2362.5 6682.5 2430.0 6930.0 2745.0 6952.5 DrawSplineSection
	2745.0 6952.5 3060.0 6975.0 3217.5 7065.0 DrawSplineSection
	3375.0 7155.0 l  gs col-1 s gr
 gr

% arrowhead
n 3262 7056 m 3351 7141 l 3232 7108 l 3247 7082 l 3262 7056 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2035 8061 m 1914 8087 l 2008 8007 l 1863 8080 l 1890 8134 l  cp clip
n 2205.0 7515.0 m 2362.5 7515.0 l
	2362.5 7515.0 2520.0 7515.0 2520.0 7762.5 DrawSplineSection
	2520.0 7762.5 2520.0 8010.0 2295.0 8010.0 DrawSplineSection
	2295.0 8010.0 2070.0 8010.0 1980.0 8055.0 DrawSplineSection
	1890.0 8100.0 l  gs col-1 s gr
 gr

% arrowhead
n 2035 8061 m 1914 8087 l 2008 8007 l 2021 8034 l 2035 8061 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2029 8718 m 1912 8760 l 1996 8668 l 1861 8758 l 1894 8808 l  cp clip
n 2205.0 7785.0 m 2407.5 7785.0 l
	2407.5 7785.0 2610.0 7785.0 2610.0 8032.5 DrawSplineSection
	2610.0 8032.5 2610.0 8280.0 2610.0 8482.5 DrawSplineSection
	2610.0 8482.5 2610.0 8685.0 2317.5 8685.0 DrawSplineSection
	2317.5 8685.0 2025.0 8685.0 1957.5 8730.0 DrawSplineSection
	1890.0 8775.0 l  gs col-1 s gr
 gr

% arrowhead
n 2029 8718 m 1912 8760 l 1996 8668 l 2012 8693 l 2029 8718 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3520 8736 m 3399 8762 l 3493 8682 l 3348 8755 l 3375 8809 l  cp clip
n 3690.0 7785.0 m 3892.5 7785.0 l
	3892.5 7785.0 4095.0 7785.0 4095.0 8032.5 DrawSplineSection
	4095.0 8032.5 4095.0 8280.0 4095.0 8482.5 DrawSplineSection
	4095.0 8482.5 4095.0 8685.0 3825.0 8685.0 DrawSplineSection
	3825.0 8685.0 3555.0 8685.0 3465.0 8730.0 DrawSplineSection
	3375.0 8775.0 l  gs col-1 s gr
 gr

% arrowhead
n 3520 8736 m 3399 8762 l 3493 8682 l 3506 8709 l 3520 8736 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3520 8061 m 3399 8087 l 3493 8007 l 3348 8080 l 3375 8134 l  cp clip
n 3690.0 7515.0 m 3847.5 7515.0 l
	3847.5 7515.0 4005.0 7515.0 4005.0 7762.5 DrawSplineSection
	4005.0 7762.5 4005.0 8010.0 3780.0 8010.0 DrawSplineSection
	3780.0 8010.0 3555.0 8010.0 3465.0 8055.0 DrawSplineSection
	3375.0 8100.0 l  gs col-1 s gr
 gr

% arrowhead
n 3520 8061 m 3399 8087 l 3493 8007 l 3506 8034 l 3520 8061 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
3930 9145 m 3806 9131 l 3922 9085 l 3761 9107 l 3769 9167 l  cp clip
n 5130.0 5220.0 m 5130.0 6930.0 l
	5130.0 6930.0 5130.0 8640.0 4950.0 8820.0 DrawSplineSection
	4950.0 8820.0 4770.0 9000.0 4275.0 9067.5 DrawSplineSection
	3780.0 9135.0 l  gs col-1 s gr
 gr

% arrowhead
n 3930 9145 m 3806 9131 l 3922 9085 l 3926 9115 l 3930 9145 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
2444 9150 m 2321 9132 l 2438 9091 l 2277 9107 l 2283 9166 l  cp clip
n 3420.0 5670.0 m 3217.5 6030.0 l
	3217.5 6030.0 3015.0 6390.0 2880.0 6750.0 DrawSplineSection
	2880.0 6750.0 2745.0 7110.0 2745.0 8100.0 DrawSplineSection
	2745.0 8100.0 2745.0 9090.0 2520.0 9112.5 DrawSplineSection
	2295.0 9135.0 l  gs col-1 s gr
 gr

% arrowhead
n 2444 9150 m 2321 9132 l 2438 9091 l 2441 9120 l 2444 9150 l  cp gs 0.00 setgray ef gr  col-1 s
% Open spline
gs  clippath
740 5850 m 681 5958 l 682 5835 l 642 5992 l 700 6007 l  cp clip
n 1035.0 4455.0 m 1170.0 4455.0 l
	1170.0 4455.0 1305.0 4455.0 1282.5 4972.5 DrawSplineSection
	1282.5 4972.5 1260.0 5490.0 1012.5 5557.5 DrawSplineSection
	1012.5 5557.5 765.0 5625.0 720.0 5805.0 DrawSplineSection
	675.0 5985.0 l  gs col-1 s gr
 gr

% arrowhead
n 740 5850 m 681 5958 l 682 5835 l 711 5842 l 740 5850 l  cp gs 0.00 setgray ef gr  col-1 s
/Times-Roman ff 150.00 scf sf
495 180 m
gs 1 -1 sc (Query) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 1170 m
gs 1 -1 sc  270.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 945 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 675 m
gs 1 -1 sc (targetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 405 m
gs 1 -1 sc (rtable) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 1350 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 1575 m
gs 1 -1 sc (resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 1845 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1755 1350 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1530 1575 m
gs 1 -1 sc (resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1530 1845 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
495 6165 m
gs 1 -1 sc (Query) col-1 sh gr
/Times-Roman ff 150.00 scf sf
540 7155 m
gs 1 -1 sc  270.0 rot (. . .) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 6390 m
gs 1 -1 sc (rtable) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 6660 m
gs 1 -1 sc (targetlist) col-1 sh gr
/Times-Roman ff 150.00 scf sf
270 6930 m
gs 1 -1 sc (qual) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3240 7335 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 7560 m
gs 1 -1 sc (resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 7830 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1755 7335 m
gs 1 -1 sc (TLE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1530 7560 m
gs 1 -1 sc (resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1530 7830 m
gs 1 -1 sc (expr) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3150 8280 m
gs 1 -1 sc (Resdom) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3015 8505 m
gs 1 -1 sc (resname: C3) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3375 6885 m
gs 1 -1 sc (relname: "C") col-1 sh gr
/Times-Roman ff 150.00 scf sf
3600 6660 m
gs 1 -1 sc (RTE) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1620 2970 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 3195 m
gs 1 -1 sc (varno: 1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 3480 m
gs 1 -1 sc (varattno: 1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 2970 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 3195 m
gs 1 -1 sc (varno: 1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 3480 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1620 8955 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 9180 m
gs 1 -1 sc (varno: 1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3105 8955 m
gs 1 -1 sc (VAR) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 9180 m
gs 1 -1 sc (varno: 1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
1575 9465 m
gs 1 -1 sc (varattno: 1) col-1 sh gr
/Times-Roman ff 150.00 scf sf
3060 9465 m
gs 1 -1 sc (varattno: 2) col-1 sh gr
showpage
$F2psEnd
rs
%%EndDocument
 @endspecial 517 3325 a(Figure)12 b(3.14:)j(Data)e(structure)e(of)h
Fk(A)g Fo(\\)f Fk(C)16 b Ft(after)11 b(query)h(re)o(writing)p
eop
%%Page: 110 110
110 109 bop 270 60 a Ft(110)57 b Fm(CHAPTER)14 b(3.)28
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
270 234 y Ft(If)h(the)g(user')m(s)g(query)g(in)n(v)o(olv)o(es)h
Fp(union)f Ft(as)g(well)h(as)g Fp(intersect)f Ft(or)g
Fp(e)o(xcept)h Ft(there)e(will)h(be)h(more)f Fr(Query)270
294 y Ft(nodes)f(of)f(the)h(form)f(sho)o(wn)g(in)h(\002gure)f(3.14.)16
b(One)c(will)f(be)h(the)f(topmost)h(node)f(\(as)h(described)g(abo)o(v)o
(e\))270 354 y(and)j(the)g(others)g(will)f(be)h(collected)g(in)g(a)g
(list)g(which)f(is)i(attached)f(to)f(the)h(\002eld)g
Fr(unionClause)f Ft(of)270 413 y(the)k(topmost)f(node.)32
b(\(The)18 b Fp(intersectClause)g Ft(\002elds)g(of)f(all)g
Fr(Query)h Ft(nodes)g(will)f(be)h(set)g(to)f Fr(NULL)270
473 y Ft(because)c(the)o(y)g(are)f(no)g(longer)g(needed.\))270
593 y(The)28 b(function)f Fr(pg)p 632 593 15 2 v 17 w(parse)p
799 593 V 18 w(and)p 907 593 V 17 w(plan\(\))g Ft(is)h(responsible)g
(for)e(in)n(v)o(oking)h(the)h(re)o(write)e(pro-)270 653
y(cedure.)16 b(It)c(can)g(be)h(found)e(in)h(the)h(\002le)f
Fk(:)c(:)g(:)p Fr(/src/backend/tcop/postgres.c)p Ft(.)330
845 y Fr(List)29 b(*)330 905 y(pg_parse_and_plan\(char)e
(*query_string,)i(Oid)g(*typev,)868 965 y(int)g(nargs,)868
1024 y(QueryTreeList)f(**queryListP,)868 1084 y(CommandDest)g(dest\))
330 1144 y({)1107 1204 y(.)1107 1264 y(.)1107 1323 y(.)390
1383 y(/*)h(Rewrite)g(Union,)h(Intersect)e(and)i(Except)f(Queries)419
1443 y(*)h(to)g(normal)f(Union)g(Queries)h(using)f(IN)h(and)f(NOT)419
1503 y(*)h(IN)g(subselects)f(*/)390 1562 y
(if\(querytree->intersectClaus)o(e)e(!=)j(NIL\))390 1622
y({)449 1682 y(querytree)f(=)h(Except_Intersect_Rewrite\(querytr)o
(ee\);)390 1742 y(})1107 1802 y(.)1107 1861 y(.)1107
1921 y(.)330 1981 y(})270 2150 y Ft(Here)14 b(are)f(the)h(functions)f
(that)h(ha)o(v)o(e)g(been)g(added)g(to)g(perform)e(the)i(functionality)
e(described)i(abo)o(v)o(e.)270 2210 y(The)o(y)f(can)g(be)f(found)g(in)g
(the)g(\002le)g Fk(:)c(:)g(:)q Fr(/src/backend/rewrite/rewrite)o
(Handler.c)o Ft(.)345 2379 y Fo(\017)25 b Fr(Except)p
578 2379 V 17 w(Intersect)p 865 2379 V 17 w(Rewrite\(\))395
2439 y Ft(Re)o(writes)19 b(queries)g(in)n(v)o(olving)f
Fp(union)h(clauses)p Ft(,)j Fp(intersect)d(clauses)h
Ft(and)f Fp(e)o(xcept)g(clauses)h Ft(to)395 2499 y(semantiacally)12
b(equi)o(v)o(alent)f(queries)i(that)f(use)h Fr(IN)f Ft(and)g
Fr(NOT)30 b(IN)12 b Ft(subselects)i(instead.)395 2625
y(The)23 b Fp(oper)o(ator)g(tr)n(ee)h Ft(is)f(attached)g(to)f
Fr(intersectClause)g Ft(\(see)h(rule)f Fr(SelectStmt)395
2685 y Ft(abo)o(v)o(e\))f(of)f(the)h Fp(parsetr)n(ee)h
Ft(gi)o(v)o(en)f(as)g(an)g(ar)o(gument.)41 b(First)21
b(we)g(sa)o(v)o(e)g(some)h(clauses)g(\(the)395 2745 y
Fr(sortClause)p Ft(,)j(the)e Fr(unique)29 b(flag)23 b
Ft(etc.\).)48 b(Then)23 b(we)h(translate)f(the)g Fp(oper)o(ator)g(tr)n
(ee)395 2804 y Ft(to)d(DNF)g(\()p Fp(Disjunctive)g(Normal)h(F)-5
b(orm)p Ft(\))20 b(by)h Fr(cnfify\(\))p Ft(.)39 b(Note)20
b(that)g Fr(cnfify\(\))g Ft(pro-)395 2864 y(duces)27
b(CNF)g(b)o(ut)g(as)h(we)f(e)o(xchanged)h Fr(AND)f Ft(nodes)g(with)g
Fr(OR)g Ft(nodes)g(within)g(function)395 2924 y Fr(A)p
428 2924 V 17 w(Expr)p 565 2924 V 18 w(to)p 643 2924
V 18 w(Expr\(\))17 b Ft(earlier)g(we)h(get)f(DNF)h(when)g(we)g(e)o
(xchange)g Fr(AND)f Ft(nodes)h(and)g Fr(OR)395 2984 y
Ft(nodes)c(again)g(in)g(the)g(result.)21 b(No)o(w)14
b(we)h(create)f(a)g(ne)o(w)g(\(re)o(written\))e(query)i(by)g(e)o
(xamining)g(the)395 3044 y(ne)o(w)f Fp(oper)o(ator)i(tr)n(ee)f
Ft(which)g(is)g(in)g(DNF)f(no)o(w)m(.)20 b(F)o(or)13
b(e)o(v)o(ery)h Fr(AND)f Ft(node)h(we)g(create)g(an)g(entry)f(in)395
3103 y(the)e Fp(union)g(list)h Ft(and)g(for)f(e)o(v)o(ery)g
Fr(OR)h Ft(node)f(we)h(create)g(an)g Fr(IN)f Ft(subselect.)16
b(\()p Fr(NOT)29 b(IN)12 b Ft(subselects)395 3163 y(are)i(created)g
(for)f Fr(OR)30 b(NOT)14 b Ft(nodes\).)21 b(The)14 b(\002rst)g(entry)g
(of)f(the)i Fp(union)e(list)h Ft(is)h(handed)f(back)g(b)o(ut)395
3223 y(before)e(that)h(the)h(sa)o(v)o(ed)g(clauses)g(\()p
Fr(sortClause)e Ft(etc.\))18 b(are)13 b(restored)g(to)g(the)h(ne)o(w)f
(top)g(node.)395 3283 y(Note)d(that)g(the)g(ne)o(w)g(top)h(node)f(can)g
(dif)o(fer)f(from)h(the)g(one)g(of)g(the)g Fp(parsetr)n(ee)i
Ft(gi)o(v)o(en)e(as)h(ar)o(gument)395 3342 y(because)k(of)g(the)f
(translation)h(into)f(DNF)l(.)h(That')m(s)h(why)e(we)h(had)g(to)g(sa)o
(v)o(e)g(the)g Fr(sortClause)395 3402 y Ft(etc.)p eop
%%Page: 111 111
111 110 bop 198 60 a Fm(3.8.)26 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)327
b Ft(111)382 234 y Fr(Query)30 b(*)382 294 y(Except_Intersect_Rewrite)e
(\(Query)h(*parsetree\))382 354 y({)1219 413 y(.)1219
473 y(.)1219 533 y(.)442 593 y(/*)h(Save)f(some)h(fields,)f(to)g(be)h
(able)f(to)h(restore)f(them)472 653 y(*)h(to)f(the)h(resulting)f(top)g
(node)h(at)f(the)h(end)g(of)f(the)472 712 y(*)h(function)472
772 y(*/)442 832 y(sortClause)f(=)h(parsetree->sortClause;)442
892 y(uniqueFlag)f(=)h(parsetree->uniqueFlag;)442 951
y(into)g(=)f(parsetree->into;)442 1011 y(isBinary)g(=)h
(parsetree->isBinary;)442 1071 y(isPortal)f(=)h(parsetree->isPortal;)
442 1191 y(/*)g(Transform)f(the)g(SelectStmt)g(nodes)g(into)h(Query)f
(nodes)472 1250 y(*)h(as)f(usually)h(done)f(by)h
(transformSelectStmt\(\))d(earlier.)472 1310 y(*)j(/)442
1370 y(intersectClause)e(=)502 1430 y(\(List)h
(*\)intersect_tree_analyze\()741 1489 y(\(Node)g
(*\)parsetree->intersectClause,)741 1549 y(\(Node)g
(*\)lfirst\(parsetree->unionClause\),)741 1609 y(\(Node)g
(*\)parsetree\);)1219 1669 y(.)1219 1729 y(.)1219 1788
y(.)442 1848 y(/*)h(Transform)f(the)g(operator)g(tree)h(to)f(DNF)h(*/)
442 1908 y(intersectClause)e(=)801 1968 y(cnfify\(\(Expr)g
(*\)intersectClause,)g(true\);)442 2027 y(/*)i(For)f(every)h(entry)f
(of)h(the)f(intersectClause)f(list)i(we)472 2087 y(*)g(generate)f(one)g
(entry)h(in)f(the)h(union_list)472 2147 y(*/)442 2207
y(foreach\(intersect,)e(intersectClause\))442 2267 y({)502
2326 y(/*)i(For)f(every)g(OR)h(we)g(create)f(an)h(IN)f(subselect)g(and)
532 2386 y(*)h(for)f(every)g(OR)h(NOT)g(we)f(create)g(a)h(NOT)g(IN)f
(subselect,)532 2446 y(*/)502 2506 y(intersect_list)f(=)i(NIL;)502
2565 y(create_list\(\(Node)e(*\)lfirst\(intersect\),)861
2625 y(&intersect_list\);)502 2685 y(/*)i(The)f(first)g(node)h(will)f
(become)g(the)h(Select)f(Query)532 2745 y(*)h(node,)f(all)g(other)h
(nodes)f(are)h(transformed)e(into)532 2804 y(*)i(subselects)e(under)i
(this)f(node!)532 2864 y(*/)502 2924 y(intersect_node)f(=)i(\(Query)f
(*\)lfirst\(intersect_list\);)502 2984 y(intersect_list)f(=)i
(lnext\(intersect_list\);)1219 3044 y(.)1219 3103 y(.)1219
3163 y(.)502 3223 y(/*)g(Transform)e(all)i(remaining)f(nodes)g(into)h
(subselects)532 3283 y(*)g(and)f(add)h(them)f(to)h(the)f
(qualifications)g(of)g(the)532 3342 y(*)h(Select)f(Query)g(node)532
3402 y(*/)p eop
%%Page: 112 112
112 111 bop 270 60 a Ft(112)60 b Fm(CHAPTER)14 b(3.)25
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
574 234 y Fr(while\(intersect_list)28 b(!=)h(NIL\))574
294 y({)634 354 y(n)g(=)h(makeNode\(SubLink\);)634 473
y(/*)f(Here)h(we)f(got)h(an)g(OR)f(so)h(transform)f(it)g(to)h(an)664
533 y(*)f(IN)h(subselect)664 593 y(*/)634 653 y
(if\(IsA\(lfirst\(intersect_list)o(\),)d(Query\)\))634
712 y({)1291 772 y(.)1291 832 y(.)1291 892 y(.)693 951
y(n->subselect)i(=)h(lfirst\(intersect_list\);)693 1011
y(op)g(=)g("=";)693 1071 y(n->subLinkType)f(=)h(ANY_SUBLINK;)693
1131 y(n->useor)f(=)h(false;)634 1191 y(})634 1310 y(/*)f(Here)h(we)f
(got)h(an)g(OR)f(NOT)h(node)f(so)h(transform)664 1370
y(*)f(it)h(to)g(a)f(NOT)h(IN)60 b(subselect)664 1430
y(*/)634 1489 y(else)634 1549 y({)1291 1609 y(.)1291
1669 y(.)1291 1729 y(.)693 1788 y(n->subselect)29 b(=)783
1848 y(\(Node)g(*\)lfirst\(\(\(Expr)g(*\))962 1908 y
(lfirst\(intersect_list\)\)->args\);)693 1968 y(op)h(=)g("<>";)693
2027 y(n->subLinkType)f(=)h(ALL_SUBLINK;)693 2087 y(n->useor)f(=)h
(true;)634 2147 y(})634 2267 y(/*)f(Prepare)g(the)h(lefthand)f(side)g
(of)h(the)g(Sublinks:)664 2326 y(*)f(All)h(the)f(entries)h(of)f(the)h
(targetlist)e(must)i(be)664 2386 y(*)f(\(IN\))h(or)f(must)h(not)f(be)h
(\(NOT)f(IN\))h(the)g(subselect)664 2446 y(*/)634 2506
y(foreach\(elist,)e(intersect_node->targetList\))634
2565 y({)693 2625 y(Node)239 b(*expr)29 b(=)h(lfirst\(elist\);)693
2685 y(TargetEntry)f(*tent)g(=)h(\(TargetEntry)f(*\)expr;)693
2804 y(n->lefthand)g(=)903 2864 y(lappend\(n->lefthand,)e
(tent->expr\);)634 2924 y(})634 3044 y(/*)i(The)h(first)f(arguments)g
(of)h(oper)f(also)h(have)f(to)h(be)664 3103 y(*)f(created)g(for)h(the)g
(sublink)f(\(they)g(are)g(the)h(same)664 3163 y(*)f(as)h(the)g
(lefthand)f(side!\))664 3223 y(*/)634 3283 y(left_expr)g(=)g
(n->lefthand;)634 3342 y(right_expr)f(=)783 3402 y(\(\(Query)h
(*\)\(n->subselect\)\)->targetList;)p eop
%%Page: 113 113
113 112 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)324
b Ft(113)562 234 y Fr(foreach\(elist,)28 b(left_expr\))562
294 y({)621 354 y(Node)269 b(*lexpr)29 b(=)h(lfirst\(elist\);)621
413 y(Node)269 b(*rexpr)29 b(=)h(lfirst\(right_expr\);)621
473 y(TargetEntry)f(*tent)g(=)h(\(TargetEntry)f(*\))g(rexpr;)621
533 y(Expr)269 b(*op_expr;)621 653 y(op_expr)30 b(=)f(make_op\(op,)g
(lexpr,)g(tent->expr\);)621 712 y(n->oper)h(=)f(lappend\(n->oper,)f
(op_expr\);)621 772 y(right_expr)h(=)h(lnext\(right_expr\);)562
832 y(})562 951 y(/*)f(If)h(the)g(Select)f(Query)g(node)g(has)h
(aggregates)592 1011 y(*)f(in)h(use)g(add)f(all)h(the)f(subselects)g
(to)h(the)592 1071 y(*)f(HAVING)h(qual)f(else)g(to)h(the)g(WHERE)f
(qual)592 1131 y(*/)562 1191 y(if\(intersect_node->hasAggs)e(==)i
(false\))562 1250 y({)621 1310 y(AddQual\(intersect_node,)f(\(Node)h
(*\)n\);)562 1370 y(})562 1430 y(else)562 1489 y({)621
1549 y(AddHavingQual\(intersect_node,)e(\(Node)i(*\)n\);)562
1609 y(})562 1729 y(/*)g(Now)h(we)g(got)f(sublinks)g(*/)562
1788 y(intersect_node->hasSubLinks)d(=)k(true;)562 1848
y(intersect_list)e(=)i(lnext\(intersect_list\);)502 1908
y(})502 1968 y(intersect_node->intersectClaus)o(e)d(=)j(NIL;)502
2027 y(union_list)f(=)g(lappend\(union_list,)f(intersect_node\);)442
2087 y(})442 2207 y(/*)i(The)f(first)h(entry)f(to)h(union_list)e(is)i
(our)472 2267 y(*)g(new)f(top)h(node)472 2326 y(*/)442
2386 y(result)f(=)h(\(Query)f(*\)lfirst\(union_list\);)442
2506 y(/*)h(attach)f(the)h(rest)f(to)h(unionClause)e(*/)442
2565 y(result->unionClause)g(=)i(lnext\(union_list\);)442
2685 y(/*)g(Attach)f(all)h(the)f(items)g(saved)h(in)f(the)472
2745 y(*)h(beginning)f(of)g(the)h(function)f(*/)442 2804
y(result->sortClause)f(=)i(sortClause;)442 2864 y(result->uniqueFlag)e
(=)i(uniqueFlag;)442 2924 y(result->into)f(=)g(into;)442
2984 y(result->isPortal)f(=)i(isPortal;)442 3044 y(result->isBinary)e
(=)i(isBinary;)1219 3103 y(.)1219 3163 y(.)1219 3223
y(.)442 3283 y(return)59 b(result;)382 3342 y(})p eop
%%Page: 114 114
114 113 bop 270 60 a Ft(114)60 b Fm(CHAPTER)14 b(3.)25
b(POSTGRESQL)13 b(FR)n(OM)f(THE)i(PR)n(OGRAMMER'S)f(POINT)f(OF)g(VIEW)
345 234 y Fo(\017)25 b Fr(create)p 578 234 15 2 v 17
w(list\(\))395 294 y Ft(Create)19 b(a)h(list)g(of)f(nodes)h(that)f(are)
g(either)h Fr(Query)f Ft(nodes)h(or)f Fr(NOT)g Ft(nodes)h(follo)o(wed)e
(by)i(a)395 354 y Fr(Query)11 b Ft(node.)16 b(The)c Fp(tr)n(ee)h
Ft(gi)o(v)o(en)f(in)f Fr(ptr)h Ft(contains)g(at)g(least)h(one)f
Fp(non)f(ne)n(gated)h Fr(Query)g Ft(node.)395 413 y(This)h(node)f(is)h
(put)f(to)g(the)g(be)o(ginning)g(of)g(the)g(list.)454
533 y Fr(void)30 b(create_list\(Node)e(*ptr,)962 593
y(List)i(**intersect_list\))454 653 y({)514 712 y(List)g(*arg;)514
832 y(if\(IsA\(ptr,Query\)\))514 892 y({)574 951 y(/*)g(The)f(non)h
(negated)f(node)g(is)h(attached)f(at)g(the)604 1011 y(*)h(beginning)e
(\(lcons\))i(*/)574 1071 y(*intersect_list)e(=)i(lcons\(ptr,)f
(*intersect_list\);)574 1131 y(return;)514 1191 y(})514
1250 y(if\(IsA\(ptr,Expr\)\))514 1310 y({)574 1370 y(if\(\(\(Expr)g
(*\)ptr\)->opType)f(==)i(NOT_EXPR\))574 1430 y({)634
1489 y(/*)f(negated)g(nodes)h(are)f(appended)g(to)h(the)664
1549 y(*)f(end)h(\(lappend\))664 1609 y(*/)634 1669 y(*intersect_list)e
(=)843 1729 y(lappend\(*intersect_list,)f(ptr\);)634
1788 y(return;)574 1848 y(})574 1908 y(else)574 1968
y({)634 2027 y(foreach\(arg,)h(\(\(Expr)h(*\)ptr\)->args\))634
2087 y({)693 2147 y(create_list\(lfirst\(arg\),)f(intersect_list\);)634
2207 y(})634 2267 y(return;)574 2326 y(})574 2386 y(return;)514
2446 y(})454 2506 y(})345 2625 y Fo(\017)d Fr(intersect)p
668 2625 V 16 w(tree)p 804 2625 V 18 w(analyze\(\))395
2685 y Ft(The)32 b(nodes)h(gi)o(v)o(en)f(in)g Fr(tree)g
Ft(are)g(not)g(transformed)f(yet)h(so)g(process)h(them)f(using)395
2745 y Fr(parse)p 548 2745 V 17 w(analyze\(\))p Ft(.)d(The)18
b(node)f(gi)o(v)o(en)g(in)g Fr(first)p 1417 2745 V 18
w(select)f Ft(has)i(already)f(been)g(pro-)395 2804 y(cessed,)e(so)f
(don')o(t)e(transform)h(it)g(again)g(b)o(ut)g(return)g(a)g(pointer)g
(to)g(the)h(already)f(processed)h(v)o(er)o(-)395 2864
y(sion)e(gi)o(v)o(en)g(in)g Fr(parsetree)g Ft(instead.)454
2984 y Fr(Node)30 b(*intersect_tree_analyze\(Node)c(*tree,)873
3044 y(Node)j(*first_select,)f(Node)i(*parsetree\))454
3103 y({)514 3163 y(Node)g(*result;)514 3223 y(List)g(*arg;)514
3342 y(if\(IsA\(tree,)f(SelectStmt\)\))514 3402 y({)p
eop
%%Page: 115 115
115 114 bop 198 60 a Fm(3.8.)29 b(THE)13 b(REALIZA)-6
b(TION)14 b(OF)e(UNION,)g(INTERSECT)i(AND)f(EXCEPT)324
b Ft(115)502 234 y Fr(QueryTreeList)28 b(*qtree;)502
354 y(/*)i(If)f(we)h(get)f(to)h(the)g(tree)f(given)g(in)h(first_select)
532 413 y(*)g(return)f(parsetree)g(instead)g(of)g(performing)532
473 y(*)h(parse_analyze\(\))e(*/)502 533 y(if\(tree)h(==)h
(first_select\))502 593 y({)562 653 y(result)f(=)h(parsetree;)502
712 y(})502 772 y(else)502 832 y({)562 892 y(/*)f(transform)g(the)h
(unprocessed)e(Query)i(nodes)f(*/)562 951 y(qtree)g(=)711
1011 y(parse_analyze\(lcons\(tree,)e(NIL\),)i(NULL\);)562
1071 y(result)g(=)h(\(Node)f(*\)qtree->qtrees[0];)502
1131 y(})442 1191 y(})442 1250 y(if\(IsA\(tree,Expr\)\))442
1310 y({)502 1370 y(/*)h(Call)f(recursively)g(for)g(every)g(argument)g
(*/)532 1430 y(foreach\(arg,)f(\(\(Expr)i(*\)tree\)->args\))532
1489 y({)592 1549 y(lfirst\(arg\))e(=)711 1609 y
(intersect_tree_analyze\(lfirst\(ar)o(g\),)1100 1669
y(first_select,)g(parsetree\);)532 1729 y(})532 1788
y(result)h(=)h(tree;)442 1848 y(})442 1908 y(return)f(result;)382
1968 y(})p eop
%%Page: 116 116
116 115 bop 270 633 a Fq(Summary)270 892 y Ft(PostgreSQL)14
b(has)g(become)g(one)g(of)g(the)g(most)g(popular)f(non)h(commercial)g
(RDBMSs)h(in)e(the)i(UNIX)270 951 y(world.)27 b(It)16
b(pro)o(vides)h(an)f(e)o(xtended)h(subset)g(of)f(the)h(SQL92)g
(standard)f(as)h(query)f(language,)i(allo)o(ws)270 1011
y(concurrent)c(database)i(access,)h(pro)o(vides)e(a)h(huge)f(amount)f
(of)h(datatypes,)h(etc.)25 b(At)15 b(the)g(the)g(time)g(of)270
1071 y(writing)9 b(this)i(document)e(the)i(implemented)e(part)h(of)g
(SQL92)g(in)g(PostgreSQL)g(lacked)g(two)f(important)270
1131 y(features:)345 1230 y Fo(\017)25 b Ft(The)12 b
Fp(having)g(clause)h Ft(was)g(not)f(implemented.)345
1330 y Fo(\017)25 b Ft(The)12 b(use)h(of)f Fp(e)o(xcept)h
Ft(and)f Fp(intersect)h Ft(statements)g(was)f(not)g(possible.)270
1430 y(The)19 b(implementation)f(of)g(these)h(two)f(items)g(was)h(the)g
(moti)o(v)o(ation)e(for)h(the)g(whole)h(work.)33 b(When)270
1489 y(I)22 b(started)g(to)g(implement)g(the)g(abo)o(v)o(e)h(mentioned)
e(features,)k(I)d(noticed)g(that)g(there)g(was)g(almost)270
1549 y(no)g(documentation)e(on)i(the)g(internal)f(structure)g(of)g
(PostgreSQL)g(a)o(v)o(ailable)g(that)h(could)f(help)h(a)270
1609 y(programmer)c(to)h(\002nd)g(his)h(way)f(in.)37
b(So)20 b(I)f(decided)g(to)h(include)f(all)h(the)f(kno)o(wledge)g(I)g
(collected)270 1669 y(while)14 b(working)e(with)i(the)g(source)g(code)g
(into)f(this)h(document,)h(hoping)e(that)h(it)f(will)h(be)g(a)g(useful)
g(for)270 1729 y(an)o(y)19 b(ne)o(wcomer)f(who)h(wants)g(to)f(enhance)i
(PostgreSQL)e(etc.)35 b(Additionally)18 b(I)h(included)f(a)h(short)270
1788 y(discussion)13 b(on)g(SQL)g(and)g(a)g(description)f(of)g
(PostgreSQL)-5 b(')m(s)14 b(features)e(\(like)g Fp(triggers)g
Ft(etc.\))17 b(and)12 b(ho)o(w)270 1848 y(the)o(y)g(can)h(be)g(used.)
270 1968 y(Chapter)24 b(1)h(discusses)h(the)f(theoretical)f
(\(mathematical\))f(background)h(of)h(relational)e(database)270
2027 y(management)12 b(systems)h(\(RDBMSs\))g(ending)f(in)g(a)g(short)h
(description)e(of)h(SQL.)270 2147 y(Chapter)30 b(2)g(\002rst)g(gi)o(v)o
(es)g(an)h(o)o(v)o(ervie)o(w)e(of)h(ho)o(w)g(to)g(setup)g(and)g
(administrate)g(PostgreSQL.)270 2207 y(Ne)o(xt)15 b(some)g(of)f
(PostgreSQL)-5 b(')m(s)15 b(special)g(features)g(are)g(presented)f
(\(i.e.)23 b Fp(multiple)14 b(inheritance)p Ft(,)i Fp(user)270
2267 y(de\002ned)c(data)g(types)p Ft(,)i Fp(rules)p Ft(,)f
Fp(triggers)p Ft(,)f(etc.\))k(using)c(a)h(lot)f(of)g(e)o(xamples.)270
2386 y(Chapter)19 b(3)g(\002rst)g(gi)o(v)o(es)g(an)g(o)o(v)o(ervie)o(w)
g(on)g(the)g(internal)g(structure)f(of)h(PostgreSQL)g(and)g(presents)
270 2446 y(the)k(stages)g(and)g(data)f(structures)g(that)h(are)f(in)n
(v)o(olv)o(ed)h(whene)o(v)o(er)f(a)h(SQL)f(query)g(arri)o(v)o(es.)47
b(The)270 2506 y Fp(parser)15 b(stage)p Ft(,)g(the)f
Fp(rule)h(system)h Ft(\(which)e(is)g(mainly)g(used)h(for)f(the)h
(implementation)e(of)h Fp(vie)o(ws)p Ft(\),)i(the)270
2565 y Fp(planner/optimizer)f Ft(and)f(the)h Fp(e)o(xecutor)g
Ft(are)f(described)h(and)f(illustrated)g(by)h(a)f(lot)h(of)f
(\002gures.)22 b(After)270 2625 y(that)15 b(the)g(changes)h(necessary)g
(for)e(the)i(implementation)e(of)h(the)g(missing)g(features)g(\()p
Fp(having)g(clause)270 2685 y Ft(and)d Fp(e)o(xcept/intersect)p
Ft(\))h(are)f(presented)g(including)g(parts)g(of)g(the)g(added)h
(source)f(code.)1133 3552 y(116)p eop
%%Page: 117 117
117 116 bop 198 633 a Fq(Bibliograph)n(y)198 892 y Ft([D)n(A)-6
b(TE96])99 b(C.)15 b(J.)g(Date)f(with)g(H.)g(Darwen:)k
Fp(A)d(Guide)f(to)f(the)h(SQL)g(Standar)n(d)p Ft(,)h(F)o(ourth)e
(Edition,)505 951 y(Addison-W)l(esle)o(y)g(1996)198 1051
y([ULL88])127 b(Jef)o(fre)o(y)12 b(D.)h(Ullman:)i Fp(Principles)e(of)f
(Database)h(and)f(Knowledge)g(-)g(Base)i(Systems)p Ft(,)505
1111 y(V)-6 b(olume)12 b(1,)g(Computer)g(Science)h(Press)f(1988)198
1210 y([D)n(A)-6 b(TE94])99 b(C.)23 b(J.)g(Date:)36 b
Fp(An)23 b(Intr)n(oduction)e(to)h(Database)g(Systems)p
Ft(,)k(V)-6 b(ol.)23 b(1,)i(6th)d(Edition,)505 1270 y(Addison-W)l(esle)
o(y)13 b(1994)198 1370 y([LOCK98])88 b(Thomas)23 b(Lockhart:)36
b Fp(P)l(ostgr)n(eSQL)23 b(Pr)n(ogr)o(ammer')n(s)h(Guide)p
Ft(,)h(part)d(of)g(the)h(Post-)505 1430 y(greSQL)12 b(documentation.)
198 1529 y([ST)o(ON89])94 b(Michael)16 b(Stonebraker)d(et.)j(al.:)21
b Fp(On)16 b(Rules,)h(Pr)n(ocedur)n(es,)h(Cac)o(hing)d(and)g(V)l(ie)o
(ws)i(in)505 1589 y(Data)12 b(Base)i(Systems)p Ft(.)1061
3552 y(117)p eop
%%Trailer
end
userdict /end-hook known{end-hook}if
%%EOF