Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit3d09f6c

Browse files
committed
Make cost estimates for SubqueryScan more realistic: charge cpu_tuple_cost
for each row processed, and don't forget the evaluation cost of anyrestriction clauses attached to the node. Per discussion with Greg Stark.
1 parentb800196 commit3d09f6c

File tree

4 files changed

+53
-9
lines changed

4 files changed

+53
-9
lines changed

‎src/backend/optimizer/path/costsize.c

Lines changed: 33 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -49,7 +49,7 @@
4949
* Portions Copyright (c) 1994, Regents of the University of California
5050
*
5151
* IDENTIFICATION
52-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.109 2003/06/29 23:05:04 tgl Exp $
52+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.110 2003/07/14 22:35:54 tgl Exp $
5353
*
5454
*-------------------------------------------------------------------------
5555
*/
@@ -415,6 +415,38 @@ cost_tidscan(Path *path, Query *root,
415415
path->total_cost=startup_cost+run_cost;
416416
}
417417

418+
/*
419+
* cost_subqueryscan
420+
* Determines and returns the cost of scanning a subquery RTE.
421+
*/
422+
void
423+
cost_subqueryscan(Path*path,RelOptInfo*baserel)
424+
{
425+
Coststartup_cost;
426+
Costrun_cost;
427+
Costcpu_per_tuple;
428+
429+
/* Should only be applied to base relations that are subqueries */
430+
Assert(baserel->relid>0);
431+
Assert(baserel->rtekind==RTE_SUBQUERY);
432+
433+
/*
434+
* Cost of path is cost of evaluating the subplan, plus cost of
435+
* evaluating any restriction clauses that will be attached to the
436+
* SubqueryScan node, plus cpu_tuple_cost to account for selection
437+
* and projection overhead.
438+
*/
439+
path->startup_cost=baserel->subplan->startup_cost;
440+
path->total_cost=baserel->subplan->total_cost;
441+
442+
startup_cost=baserel->baserestrictcost.startup;
443+
cpu_per_tuple=cpu_tuple_cost+baserel->baserestrictcost.per_tuple;
444+
run_cost=cpu_per_tuple*baserel->tuples;
445+
446+
path->startup_cost+=startup_cost;
447+
path->total_cost+=startup_cost+run_cost;
448+
}
449+
418450
/*
419451
* cost_functionscan
420452
* Determines and returns the cost of scanning a function RTE.

‎src/backend/optimizer/plan/createplan.c

Lines changed: 16 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.147 2003/06/29 23:05:04 tgl Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.148 2003/07/14 22:35:54 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -811,6 +811,8 @@ create_subqueryscan_plan(Path *best_path, List *tlist, List *scan_clauses)
811811
scan_relid,
812812
best_path->parent->subplan);
813813

814+
copy_path_costsize(&scan_plan->scan.plan,best_path);
815+
814816
returnscan_plan;
815817
}
816818

@@ -1503,8 +1505,14 @@ make_subqueryscan(List *qptlist,
15031505
SubqueryScan*node=makeNode(SubqueryScan);
15041506
Plan*plan=&node->scan.plan;
15051507

1506-
/* cost is figured here for the convenience of prepunion.c */
1508+
/*
1509+
* Cost is figured here for the convenience of prepunion.c. Note this
1510+
* is only correct for the case where qpqual is empty; otherwise caller
1511+
* should overwrite cost with a better estimate.
1512+
*/
15071513
copy_plan_costsize(plan,subplan);
1514+
plan->total_cost+=cpu_tuple_cost*subplan->plan_rows;
1515+
15081516
plan->targetlist=qptlist;
15091517
plan->qual=qpqual;
15101518
plan->lefttree=NULL;
@@ -1540,7 +1548,11 @@ make_append(List *appendplans, bool isTarget, List *tlist)
15401548
Plan*plan=&node->plan;
15411549
List*subnode;
15421550

1543-
/* compute costs from subplan costs */
1551+
/*
1552+
* Compute cost as sum of subplan costs. We charge nothing extra for
1553+
* the Append itself, which perhaps is too optimistic, but since it
1554+
* doesn't do any selection or projection, it is a pretty cheap node.
1555+
*/
15441556
plan->startup_cost=0;
15451557
plan->total_cost=0;
15461558
plan->plan_rows=0;
@@ -1556,6 +1568,7 @@ make_append(List *appendplans, bool isTarget, List *tlist)
15561568
if (plan->plan_width<subplan->plan_width)
15571569
plan->plan_width=subplan->plan_width;
15581570
}
1571+
15591572
plan->targetlist=tlist;
15601573
plan->qual=NIL;
15611574
plan->lefttree=NULL;

‎src/backend/optimizer/util/pathnode.c

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.91 2003/06/29 23:05:04 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.92 2003/07/14 22:35:54 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -686,9 +686,7 @@ create_subqueryscan_path(RelOptInfo *rel, List *pathkeys)
686686
pathnode->parent=rel;
687687
pathnode->pathkeys=pathkeys;
688688

689-
/* just copy the subplan's cost estimates */
690-
pathnode->startup_cost=rel->subplan->startup_cost;
691-
pathnode->total_cost=rel->subplan->total_cost;
689+
cost_subqueryscan(pathnode,rel);
692690

693691
returnpathnode;
694692
}

‎src/include/optimizer/cost.h

Lines changed: 2 additions & 1 deletion
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: cost.h,v 1.53 2003/06/11 15:01:15 momjian Exp $
10+
* $Id: cost.h,v 1.54 2003/07/14 22:35:54 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -56,6 +56,7 @@ extern void cost_index(Path *path, Query *root,
5656
List*indexQuals,boolis_injoin);
5757
externvoidcost_tidscan(Path*path,Query*root,
5858
RelOptInfo*baserel,List*tideval);
59+
externvoidcost_subqueryscan(Path*path,RelOptInfo*baserel);
5960
externvoidcost_functionscan(Path*path,Query*root,
6061
RelOptInfo*baserel);
6162
externvoidcost_sort(Path*path,Query*root,

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp