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Cause planner to account for evaluation costs in targetlists and

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HAVING quals.  Normally this is an insignificant effect --- but it
will not be insignificant when these clauses contain sub-selects.
The added costs cannot affect the planning of the query containing
them, but they might have an impact when the query is a sub-query
of a larger one.
This commit is contained in:
Tom Lane
2003-01-13 00:29:26 +00:00
parent d1686b42ab
commit 8ac6d952cf
3 changed files with 79 additions and 6 deletions
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57
src/backend/optimizer/plan/createplan.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.128 2002/12/12 15:49:32 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.129 2003/01/13 00:29:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1366,6 +1366,7 @@ make_subqueryscan(List *qptlist,
SubqueryScan *node = makeNode(SubqueryScan);
Plan *plan = &node->scan.plan;
/* cost is figured here for the convenience of prepunion.c */
copy_plan_costsize(plan, subplan);
plan->targetlist = qptlist;
plan->qual = qpqual;
@ -1488,7 +1489,7 @@ make_hash(List *tlist, List *hashkeys, Plan *lefttree)
*/
plan->startup_cost = plan->total_cost;
plan->targetlist = tlist;
plan->qual = NULL;
plan->qual = NIL;
plan->lefttree = lefttree;
plan->righttree = NULL;
node->hashkeys = hashkeys;
@ -1646,6 +1647,7 @@ make_agg(Query *root, List *tlist, List *qual,
Agg *node = makeNode(Agg);
Plan *plan = &node->plan;
Path agg_path; /* dummy for result of cost_agg */
QualCost qual_cost;
node->aggstrategy = aggstrategy;
node->numCols = numGroupCols;
@ -1671,6 +1673,27 @@ make_agg(Query *root, List *tlist, List *qual,
else
plan->plan_rows = numGroups;
/*
* We also need to account for the cost of evaluation of the qual
* (ie, the HAVING clause) and the tlist. Note that cost_qual_eval
* doesn't charge anything for Aggref nodes; this is okay since
* they are really comparable to Vars.
*
* See notes in grouping_planner about why this routine and make_group
* are the only ones in this file that worry about tlist eval cost.
*/
if (qual)
{
cost_qual_eval(&qual_cost, qual);
plan->startup_cost += qual_cost.startup;
plan->total_cost += qual_cost.startup;
plan->total_cost += qual_cost.per_tuple * plan->plan_rows;
}
cost_qual_eval(&qual_cost, tlist);
plan->startup_cost += qual_cost.startup;
plan->total_cost += qual_cost.startup;
plan->total_cost += qual_cost.per_tuple * plan->plan_rows;
plan->qual = qual;
plan->targetlist = tlist;
plan->lefttree = lefttree;
@ -1690,6 +1713,7 @@ make_group(Query *root,
Group *node = makeNode(Group);
Plan *plan = &node->plan;
Path group_path; /* dummy for result of cost_group */
QualCost qual_cost;
node->numCols = numGroupCols;
node->grpColIdx = grpColIdx;
@ -1706,7 +1730,23 @@ make_group(Query *root,
/* One output tuple per estimated result group */
plan->plan_rows = numGroups;
plan->qual = NULL;
/*
* We also need to account for the cost of evaluation of the tlist.
*
* XXX this double-counts the cost of evaluation of any expressions
* used for grouping, since in reality those will have been evaluated
* at a lower plan level and will only be copied by the Group node.
* Worth fixing?
*
* See notes in grouping_planner about why this routine and make_agg
* are the only ones in this file that worry about tlist eval cost.
*/
cost_qual_eval(&qual_cost, tlist);
plan->startup_cost += qual_cost.startup;
plan->total_cost += qual_cost.startup;
plan->total_cost += qual_cost.per_tuple * plan->plan_rows;
plan->qual = NIL;
plan->targetlist = tlist;
plan->lefttree = lefttree;
plan->righttree = (Plan *) NULL;
@ -1718,7 +1758,6 @@ make_group(Query *root,
* distinctList is a list of SortClauses, identifying the targetlist items
* that should be considered by the Unique filter.
*/
Unique *
make_unique(List *tlist, Plan *lefttree, List *distinctList)
{
@ -1911,6 +1950,16 @@ make_result(List *tlist,
plan->plan_width = 0; /* XXX try to be smarter? */
}
if (resconstantqual)
{
QualCost qual_cost;
cost_qual_eval(&qual_cost, (List *) resconstantqual);
/* resconstantqual is evaluated once at startup */
plan->startup_cost += qual_cost.startup + qual_cost.per_tuple;
plan->total_cost += qual_cost.startup + qual_cost.per_tuple;
}
plan->targetlist = tlist;
plan->qual = NIL;
plan->lefttree = subplan;