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Commit9f76d0d

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Fix GEQO to work again in CVS tip, by being more careful about memory
allocation in best_inner_indexscan(). While at it, simplify GEQO'sinterface to the main planner --- make_join_rel() offers exactly theAPI it really wants, whereas calling make_rels_by_clause_joins() andmake_rels_by_clauseless_joins() required jumping through hoops.Rewrite gimme_tree for clarity (sometimes iteration is much better thanrecursion), and approximately halve GEQO's runtime by recognizing thattours of the forms (a,b,c,d,...) and (b,a,c,d,...) are equivalentbecause of symmetry in make_join_rel().
1 parent9cecff0 commit9f76d0d

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7 files changed

+123
-86
lines changed

7 files changed

+123
-86
lines changed

‎src/backend/optimizer/geqo/geqo_eval.c‎

Lines changed: 66 additions & 56 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id:geqo_eval.c,v 1.59 2002/06/20 20:29:29momjian Exp $
9+
* $Header: /cvsroot/pgsql/src/backend/optimizer/geqo/geqo_eval.c,v 1.60 2002/12/16 21:30:29tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -21,6 +21,7 @@
2121

2222
#include"postgres.h"
2323

24+
#include<float.h>
2425
#include<math.h>
2526
#include<limits.h>
2627

@@ -44,6 +45,20 @@ geqo_eval(Query *root, List *initial_rels, Gene *tour, int num_gene)
4445
Costfitness;
4546
List*savelist;
4647

48+
/*
49+
* Because gimme_tree considers both left- and right-sided trees,
50+
* there is no difference between a tour (a,b,c,d,...) and a tour
51+
* (b,a,c,d,...) --- the same join orders will be considered.
52+
* To avoid redundant cost calculations, we simply reject tours where
53+
* tour[0] > tour[1], assigning them an artificially bad fitness.
54+
*
55+
* (It would be better to tweak the GEQO logic to not generate such tours
56+
* in the first place, but I'm not sure of all the implications in the
57+
* mutation logic.)
58+
*/
59+
if (num_gene >=2&&tour[0]>tour[1])
60+
returnDBL_MAX;
61+
4762
/*
4863
* Create a private memory context that will hold all temp storage
4964
* allocated inside gimme_tree().
@@ -60,11 +75,15 @@ geqo_eval(Query *root, List *initial_rels, Gene *tour, int num_gene)
6075
ALLOCSET_DEFAULT_MAXSIZE);
6176
oldcxt=MemoryContextSwitchTo(mycontext);
6277

63-
/* preserve root->join_rel_list, which gimme_tree changes */
78+
/*
79+
* preserve root->join_rel_list, which gimme_tree changes; without this,
80+
* it'll be pointing at recycled storage after the MemoryContextDelete
81+
* below.
82+
*/
6483
savelist=root->join_rel_list;
6584

6685
/* construct the best path for the given combination of relations */
67-
joinrel=gimme_tree(root,initial_rels,tour,num_gene,0,NULL);
86+
joinrel=gimme_tree(root,initial_rels,tour,num_gene);
6887

6988
/*
7089
* compute fitness
@@ -86,70 +105,61 @@ geqo_eval(Query *root, List *initial_rels, Gene *tour, int num_gene)
86105

87106
/*
88107
* gimme_tree
89-
* this routine considers only LEFT-SIDED TREES!
108+
* Form planner estimates for a join tree constructed in the specified
109+
* order.
90110
*
91111
* 'root' is the Query
92112
* 'initial_rels' is the list of initial relations (FROM-list items)
93113
* 'tour' is the proposed join order, of length 'num_gene'
94-
* 'rel_count' is number of initial_rels items already joined (initially 0)
95-
* 'old_rel' is the preceding join (initially NULL)
96114
*
97-
* Returns a new join relation incorporating all joins in a left-sided tree.
115+
* Returns a new join relation whose cheapest path is the best plan for
116+
* this join order.
117+
*
118+
* Note that at each step we consider using the next rel as both left and
119+
* right side of a join. However, we cannot build general ("bushy") plan
120+
* trees this way, only left-sided and right-sided trees.
98121
*/
99122
RelOptInfo*
100123
gimme_tree(Query*root,List*initial_rels,
101-
Gene*tour,intnum_gene,
102-
intrel_count,RelOptInfo*old_rel)
124+
Gene*tour,intnum_gene)
103125
{
104-
RelOptInfo*inner_rel;/* current relation */
105-
intinit_rel_index;
126+
RelOptInfo*joinrel;
127+
intcur_rel_index;
128+
intrel_count;
106129

107-
if (rel_count<num_gene)
130+
/*
131+
* Start with the first relation ...
132+
*/
133+
cur_rel_index= (int)tour[0];
134+
135+
joinrel= (RelOptInfo*)nth(cur_rel_index-1,initial_rels);
136+
137+
/*
138+
* And add on each relation in the specified order ...
139+
*/
140+
for (rel_count=1;rel_count<num_gene;rel_count++)
108141
{
109-
/* tree not yet finished */
110-
init_rel_index= (int)tour[rel_count];
111-
112-
inner_rel= (RelOptInfo*)nth(init_rel_index-1,initial_rels);
113-
114-
if (rel_count==0)
115-
{
116-
/* processing first join with init_rel_index = (int) tour[0] */
117-
rel_count++;
118-
returngimme_tree(root,initial_rels,
119-
tour,num_gene,
120-
rel_count,inner_rel);
121-
}
122-
else
123-
{
124-
/* tree main part */
125-
List*acceptable_rels=makeList1(inner_rel);
126-
List*new_rels;
127-
RelOptInfo*new_rel;
128-
129-
new_rels=make_rels_by_clause_joins(root,old_rel,
130-
acceptable_rels);
131-
/* Shouldn't get more than one result */
132-
Assert(length(new_rels) <=1);
133-
if (new_rels==NIL)
134-
{
135-
new_rels=make_rels_by_clauseless_joins(root,old_rel,
136-
acceptable_rels);
137-
Assert(length(new_rels) <=1);
138-
if (new_rels==NIL)
139-
elog(ERROR,"gimme_tree: failed to construct join rel");
140-
}
141-
new_rel= (RelOptInfo*)lfirst(new_rels);
142-
143-
/* Find and save the cheapest paths for this rel */
144-
set_cheapest(new_rel);
145-
146-
/* and recurse... */
147-
rel_count++;
148-
returngimme_tree(root,initial_rels,
149-
tour,num_gene,
150-
rel_count,new_rel);
151-
}
142+
RelOptInfo*inner_rel;
143+
RelOptInfo*new_rel;
144+
145+
cur_rel_index= (int)tour[rel_count];
146+
147+
inner_rel= (RelOptInfo*)nth(cur_rel_index-1,initial_rels);
148+
149+
/*
150+
* Construct a RelOptInfo representing the previous joinrel joined
151+
* to inner_rel. These are always inner joins. Note that we expect
152+
* the joinrel not to exist in root->join_rel_list yet, and so the
153+
* paths constructed for it will only include the ones we want.
154+
*/
155+
new_rel=make_join_rel(root,joinrel,inner_rel,JOIN_INNER);
156+
157+
/* Find and save the cheapest paths for this rel */
158+
set_cheapest(new_rel);
159+
160+
/* and repeat... */
161+
joinrel=new_rel;
152162
}
153163

154-
returnold_rel;/* tree finished ... */
164+
returnjoinrel;
155165
}

‎src/backend/optimizer/geqo/geqo_main.c‎

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Id:geqo_main.c,v 1.32 2002/07/20 04:59:10 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/geqo/geqo_main.c,v 1.33 2002/12/16 21:30:29 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -235,8 +235,7 @@ geqo(Query *root, int number_of_rels, List *initial_rels)
235235

236236
/* root->join_rel_list will be modified during this ! */
237237
best_rel=gimme_tree(root,initial_rels,
238-
best_tour,pool->string_length,
239-
0,NULL);
238+
best_tour,pool->string_length);
240239

241240
/* DBG: show the query plan
242241
print_plan(best_plan, root);

‎src/backend/optimizer/geqo/geqo_misc.c‎

Lines changed: 19 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Header: /cvsroot/pgsql/src/backend/optimizer/geqo/geqo_misc.c,v 1.35 2002/11/06 00:00:44 tgl Exp $
9+
* $Header: /cvsroot/pgsql/src/backend/optimizer/geqo/geqo_misc.c,v 1.36 2002/12/16 21:30:29 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -31,19 +31,25 @@
3131
/*
3232
* avg_pool
3333
*/
34-
staticfloat
34+
staticdouble
3535
avg_pool(Pool*pool)
3636
{
3737
inti;
3838
doublecumulative=0.0;
3939

40-
if (pool->size==0)
40+
if (pool->size<=0)
4141
elog(ERROR,"avg_pool: pool_size of zero");
4242

43+
/*
44+
* Since the pool may contain multiple occurrences of DBL_MAX, divide
45+
* by pool->size before summing, not after, to avoid overflow. This
46+
* loses a little in speed and accuracy, but this routine is only used
47+
* for debug printouts, so we don't care that much.
48+
*/
4349
for (i=0;i<pool->size;i++)
44-
cumulative=cumulative+pool->data[i].worth;
50+
cumulative+=pool->data[i].worth /pool->size;
4551

46-
return(float)cumulative /pool->size;
52+
returncumulative;
4753
}
4854

4955
/* print_pool
@@ -72,8 +78,10 @@ print_pool(FILE *fp, Pool *pool, int start, int stop)
7278
fprintf(fp,"%d)\t",i);
7379
for (j=0;j<pool->string_length;j++)
7480
fprintf(fp,"%d ",pool->data[i].string[j]);
75-
fprintf(fp,"%f\n",pool->data[i].worth);
81+
fprintf(fp,"%g\n",pool->data[i].worth);
7682
}
83+
84+
fflush(fp);
7785
}
7886

7987
/* print_gen
@@ -90,12 +98,14 @@ print_gen(FILE *fp, Pool *pool, int generation)
9098
lowest=pool->size>1 ?pool->size-2 :0;
9199

92100
fprintf(fp,
93-
"%5d | Best: %f Worst: %f Mean: %f Avg: %f\n",
101+
"%5d | Best: %g Worst: %g Mean: %g Avg: %g\n",
94102
generation,
95103
pool->data[0].worth,
96104
pool->data[lowest].worth,
97105
pool->data[pool->size /2].worth,
98106
avg_pool(pool));
107+
108+
fflush(fp);
99109
}
100110

101111

@@ -116,6 +126,8 @@ print_edge_table(FILE *fp, Edge *edge_table, int num_gene)
116126
}
117127

118128
fprintf(fp,"\n");
129+
130+
fflush(fp);
119131
}
120132

121133
#endif/* GEQO_DEBUG */

‎src/backend/optimizer/path/indxpath.c‎

Lines changed: 20 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.129 2002/12/15 16:17:49 tgl Exp $
12+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.130 2002/12/16 21:30:29 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -1398,6 +1398,7 @@ best_inner_indexscan(Query *root, RelOptInfo *rel,
13981398
List*ilist;
13991399
List*jlist;
14001400
InnerIndexscanInfo*info;
1401+
MemoryContextoldcontext;
14011402

14021403
/*
14031404
* Nestloop only supports inner and left joins.
@@ -1415,15 +1416,27 @@ best_inner_indexscan(Query *root, RelOptInfo *rel,
14151416
}
14161417
/*
14171418
* If there are no indexable joinclauses for this rel, exit quickly.
1418-
* Otherwise, intersect the given outer_relids with index_outer_relids
1419-
* to find the set of outer relids actually relevant for this index.
1420-
* If there are none, again we can fail immediately.
14211419
*/
14221420
if (!rel->index_outer_relids)
14231421
returnNULL;
1422+
/*
1423+
* Otherwise, we have to do path selection in the memory context of
1424+
* the given rel, so that any created path can be safely attached to
1425+
* the rel's cache of best inner paths. (This is not currently an
1426+
* issue for normal planning, but it is an issue for GEQO planning.)
1427+
*/
1428+
oldcontext=MemoryContextSwitchTo(GetMemoryChunkContext(rel));
1429+
/*
1430+
* Intersect the given outer_relids with index_outer_relids
1431+
* to find the set of outer relids actually relevant for this index.
1432+
* If there are none, again we can fail immediately.
1433+
*/
14241434
outer_relids=set_intersecti(rel->index_outer_relids,outer_relids);
14251435
if (!outer_relids)
1436+
{
1437+
MemoryContextSwitchTo(oldcontext);
14261438
returnNULL;
1439+
}
14271440
/*
14281441
* Look to see if we already computed the result for this set of
14291442
* relevant outerrels. (We include the isouterjoin status in the
@@ -1437,6 +1450,7 @@ best_inner_indexscan(Query *root, RelOptInfo *rel,
14371450
info->isouterjoin==isouterjoin)
14381451
{
14391452
freeList(outer_relids);
1453+
MemoryContextSwitchTo(oldcontext);
14401454
returninfo->best_innerpath;
14411455
}
14421456
}
@@ -1517,6 +1531,8 @@ best_inner_indexscan(Query *root, RelOptInfo *rel,
15171531
info->best_innerpath=cheapest;
15181532
rel->index_inner_paths=lcons(info,rel->index_inner_paths);
15191533

1534+
MemoryContextSwitchTo(oldcontext);
1535+
15201536
returncheapest;
15211537
}
15221538

‎src/backend/optimizer/path/joinrels.c‎

Lines changed: 10 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.57 2002/06/20 20:29:30momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinrels.c,v 1.58 2002/12/16 21:30:30tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -18,8 +18,12 @@
1818
#include"optimizer/paths.h"
1919

2020

21-
staticRelOptInfo*make_join_rel(Query*root,RelOptInfo*rel1,
22-
RelOptInfo*rel2,JoinTypejointype);
21+
staticList*make_rels_by_clause_joins(Query*root,
22+
RelOptInfo*old_rel,
23+
List*other_rels);
24+
staticList*make_rels_by_clauseless_joins(Query*root,
25+
RelOptInfo*old_rel,
26+
List*other_rels);
2327

2428

2529
/*
@@ -246,7 +250,7 @@ make_rels_by_joins(Query *root, int level, List **joinrels)
246250
* no extra test for overlap for initial rels, since the is_subset test can
247251
* only succeed when other_rel is not already part of old_rel.)
248252
*/
249-
List*
253+
staticList*
250254
make_rels_by_clause_joins(Query*root,
251255
RelOptInfo*old_rel,
252256
List*other_rels)
@@ -297,7 +301,7 @@ make_rels_by_clause_joins(Query *root,
297301
* Currently, this is only used with initial rels in other_rels, but it would
298302
* work for joining to joinrels too.
299303
*/
300-
List*
304+
staticList*
301305
make_rels_by_clauseless_joins(Query*root,
302306
RelOptInfo*old_rel,
303307
List*other_rels)
@@ -392,7 +396,7 @@ make_jointree_rel(Query *root, Node *jtnode)
392396
* (The join rel may already contain paths generated from other
393397
* pairs of rels that add up to the same set of base rels.)
394398
*/
395-
staticRelOptInfo*
399+
RelOptInfo*
396400
make_join_rel(Query*root,RelOptInfo*rel1,RelOptInfo*rel2,
397401
JoinTypejointype)
398402
{

‎src/include/optimizer/geqo.h‎

Lines changed: 2 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: geqo.h,v 1.29 2002/07/20 04:59:10 momjian Exp $
9+
* $Id: geqo.h,v 1.30 2002/12/16 21:30:30 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -74,7 +74,6 @@ extern RelOptInfo *geqo(Query *root, int number_of_rels, List *initial_rels);
7474
externCostgeqo_eval(Query*root,List*initial_rels,
7575
Gene*tour,intnum_gene);
7676
externRelOptInfo*gimme_tree(Query*root,List*initial_rels,
77-
Gene*tour,intnum_gene,
78-
intrel_count,RelOptInfo*old_rel);
77+
Gene*tour,intnum_gene);
7978

8079
#endif/* GEQO_H */

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