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Make cost estimates for SubqueryScan more realistic: charge cpu_tuple_cost

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for each row processed, and don't forget the evaluation cost of any
restriction clauses attached to the node.  Per discussion with Greg Stark.
This commit is contained in:
Tom Lane
2003-07-14 22:35:54 +00:00
parent b800196230
commit 3d09f6c560
4 changed files with 53 additions and 9 deletions
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19
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 1.147 2003/06/29 23:05:04 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.148 2003/07/14 22:35:54 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -811,6 +811,8 @@ create_subqueryscan_plan(Path *best_path, List *tlist, List *scan_clauses)
scan_relid,
best_path->parent->subplan);
copy_path_costsize(&scan_plan->scan.plan, best_path);
return scan_plan;
}
@ -1503,8 +1505,14 @@ make_subqueryscan(List *qptlist,
SubqueryScan *node = makeNode(SubqueryScan);
Plan *plan = &node->scan.plan;
/* cost is figured here for the convenience of prepunion.c */
/*
* Cost is figured here for the convenience of prepunion.c. Note this
* is only correct for the case where qpqual is empty; otherwise caller
* should overwrite cost with a better estimate.
*/
copy_plan_costsize(plan, subplan);
plan->total_cost += cpu_tuple_cost * subplan->plan_rows;
plan->targetlist = qptlist;
plan->qual = qpqual;
plan->lefttree = NULL;
@ -1540,7 +1548,11 @@ make_append(List *appendplans, bool isTarget, List *tlist)
Plan *plan = &node->plan;
List *subnode;
/* compute costs from subplan costs */
/*
* Compute cost as sum of subplan costs. We charge nothing extra for
* the Append itself, which perhaps is too optimistic, but since it
* doesn't do any selection or projection, it is a pretty cheap node.
*/
plan->startup_cost = 0;
plan->total_cost = 0;
plan->plan_rows = 0;
@ -1556,6 +1568,7 @@ make_append(List *appendplans, bool isTarget, List *tlist)
if (plan->plan_width < subplan->plan_width)
plan->plan_width = subplan->plan_width;
}
plan->targetlist = tlist;
plan->qual = NIL;
plan->lefttree = NULL;