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
106
107
|
/*-------------------------------------------------------------------------
*
* prune.c
* Routines to prune redundant paths and relations
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/prune.c,v 1.40 1999/07/15 15:19:18 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "nodes/pg_list.h"
#include "nodes/relation.h"
#include "optimizer/internal.h"
#include "optimizer/cost.h"
#include "optimizer/paths.h"
#include "optimizer/pathnode.h"
static List *merge_rel_with_same_relids(RelOptInfo *rel, Relids unjoined_relids);
/*
* merge_rels_with_same_relids
* Removes any redundant relation entries from a list of rel nodes
* 'rel_list'. Obviously, the first relation can't be a duplicate.
*
* Returns the resulting list.
*
*/
void
merge_rels_with_same_relids(List *rel_list)
{
List *i;
/*
* rel_list can shorten while running as duplicate relations are
* deleted
*/
foreach(i, rel_list)
lnext(i) = merge_rel_with_same_relids((RelOptInfo *) lfirst(i), lnext(i));
}
/*
* merge_rel_with_same_relids
* Prunes those relations from 'unjoined_relids' that are redundant with
* 'rel'. A relation is redundant if it is built up of the same
* relations as 'rel'. Paths for the redundant relation are merged into
* the pathlist of 'rel'.
*
* Returns a list of non-redundant relations, and sets the pathlist field
* of 'rel' appropriately.
*
*/
static List *
merge_rel_with_same_relids(RelOptInfo *rel, Relids unjoined_relids)
{
List *i = NIL;
List *result = NIL;
foreach(i, unjoined_relids)
{
RelOptInfo *unjoined_rel = (RelOptInfo *) lfirst(i);
if (same(rel->relids, unjoined_rel->relids))
/*
* This are on the same relations, so get the best of their
* pathlists.
*/
rel->pathlist = add_pathlist(rel,
rel->pathlist,
unjoined_rel->pathlist);
else
result = lappend(result, unjoined_rel);
}
return result;
}
/*
* rels_set_cheapest
* For each relation entry in 'rel_list' (which corresponds to a join
* relation), set pointers to the cheapest path
*/
void
rels_set_cheapest(List *rel_list)
{
List *x = NIL;
RelOptInfo *rel = (RelOptInfo *) NULL;
JoinPath *cheapest;
foreach(x, rel_list)
{
rel = (RelOptInfo *) lfirst(x);
cheapest = (JoinPath *) set_cheapest(rel, rel->pathlist);
if (IsA_JoinPath(cheapest))
rel->size = compute_joinrel_size(cheapest);
else
elog(ERROR, "non JoinPath called");
}
}
|
