1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/intro.sgml,v 1.12 2000/09/29 20:21:34 petere Exp $
-->
<chapter id="intro">
<title>Introduction</title>
<para>
This document is the user manual for the
<ulink url="http://postgresql.org/"><productname>PostgreSQL</productname></ulink>
database management system, originally developed at the University
of California at Berkeley.
<productname>PostgreSQL</productname> is based on
<ulink url="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/postgres.html">
<productname>Postgres release 4.2</productname></ulink>.
The <productname>Postgres</productname> project,
led by Professor Michael Stonebraker, was sponsored by the
Defense Advanced Research Projects Agency
(<acronym>DARPA</acronym>), the
Army Research Office (<acronym>ARO</acronym>), the National Science
Foundation (<acronym>NSF</acronym>), and ESL, Inc.
</para>
<sect1 id="intro-whatis">
<title> What is <productname>Postgres</productname>?</title>
<para>
Traditional relational database management systems
(DBMSs) support a data model consisting of a collection
of named relations, containing attributes of a specific
type. In current commercial systems, possible types
include floating point numbers, integers, character
strings, money, and dates. It is commonly recognized
that this model is inadequate for future data
processing applications.
The relational model successfully replaced previous
models in part because of its "Spartan simplicity".
However, as mentioned, this simplicity often makes the
implementation of certain applications very difficult.
<productname>Postgres</productname> offers substantial additional
power by incorporating the following four additional
basic concepts in such a way that users can easily
extend the system:
<simplelist>
<member>classes</member>
<member>inheritance</member>
<member>types</member>
<member>functions</member>
</simplelist>
</para>
<para>
Other features provide additional power and flexibility:
<simplelist>
<member>constraints</member>
<member>triggers</member>
<member>rules</member>
<member>transaction integrity</member>
</simplelist>
</para>
<para>
These features put <productname>Postgres</productname> into the
category of databases referred to as
<firstterm>object-relational</firstterm>. Note that this is distinct
from those referred to as <firstterm>object-oriented</firstterm>,
which in general are not as well suited to supporting the
traditional relational database languages.
So, although <productname>Postgres</productname> has some
object-oriented features, it is firmly in the relational database
world. In fact, some commercial databases have recently
incorporated features pioneered by <productname>Postgres</productname>.
</para>
</sect1>
&history;
&about;
&info;
¬ation;
&problems;
&y2k;
&legal;
</chapter>
<!-- Keep this comment at the end of the file
Local variables:
mode:sgml
sgml-omittag:nil
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"./reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:("/usr/lib/sgml/catalog")
sgml-local-ecat-files:nil
End:
-->
|
