diff options
Diffstat (limited to 'src/backend/optimizer/plan/createplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/createplan.c | 44 |
1 files changed, 17 insertions, 27 deletions
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index 717fcfa3cec..74e6f237b3e 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.122 2002/11/15 02:36:53 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.123 2002/11/19 23:21:58 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1684,7 +1684,8 @@ make_material(List *tlist, Plan *lefttree) Agg * make_agg(List *tlist, List *qual, AggStrategy aggstrategy, - int ngrp, AttrNumber *grpColIdx, Plan *lefttree) + int ngrp, AttrNumber *grpColIdx, long numGroups, int numAggs, + Plan *lefttree) { Agg *node = makeNode(Agg); Plan *plan = &node->plan; @@ -1692,6 +1693,7 @@ make_agg(List *tlist, List *qual, AggStrategy aggstrategy, node->aggstrategy = aggstrategy; node->numCols = ngrp; node->grpColIdx = grpColIdx; + node->numGroups = numGroups; copy_plan_costsize(plan, lefttree); @@ -1699,15 +1701,11 @@ make_agg(List *tlist, List *qual, AggStrategy aggstrategy, * Charge one cpu_operator_cost per aggregate function per input * tuple. */ - plan->total_cost += cpu_operator_cost * plan->plan_rows * - (length(pull_agg_clause((Node *) tlist)) + - length(pull_agg_clause((Node *) qual))); + plan->total_cost += cpu_operator_cost * plan->plan_rows * numAggs; /* * We will produce a single output tuple if not grouping, - * and a tuple per group otherwise. For now, estimate the number of - * groups as 10% of the number of tuples --- bogus, but how to do - * better? + * and a tuple per group otherwise. */ if (aggstrategy == AGG_PLAIN) { @@ -1716,10 +1714,7 @@ make_agg(List *tlist, List *qual, AggStrategy aggstrategy, } else { - plan->plan_rows *= 0.1; - if (plan->plan_rows < 1) - plan->plan_rows = 1; - node->numGroups = (long) plan->plan_rows; + plan->plan_rows = numGroups; } plan->state = (EState *) NULL; @@ -1735,6 +1730,7 @@ Group * make_group(List *tlist, int ngrp, AttrNumber *grpColIdx, + double numGroups, Plan *lefttree) { Group *node = makeNode(Group); @@ -1748,13 +1744,8 @@ make_group(List *tlist, */ plan->total_cost += cpu_operator_cost * plan->plan_rows * ngrp; - /* - * Estimate the number of groups as 10% of the number of tuples - * --- bogus, but how to do better? - */ - plan->plan_rows *= 0.1; - if (plan->plan_rows < 1) - plan->plan_rows = 1; + /* One output tuple per estimated result group */ + plan->plan_rows = numGroups; plan->state = (EState *) NULL; plan->qual = NULL; @@ -1786,17 +1777,16 @@ make_unique(List *tlist, Plan *lefttree, List *distinctList) /* * Charge one cpu_operator_cost per comparison per input tuple. We - * assume all columns get compared at most of the tuples. + * assume all columns get compared at most of the tuples. (XXX probably + * this is an overestimate.) */ plan->total_cost += cpu_operator_cost * plan->plan_rows * numCols; /* - * As for Group, we make the unsupported assumption that there will be - * 10% as many tuples out as in. + * plan->plan_rows is left as a copy of the input subplan's plan_rows; + * ie, we assume the filter removes nothing. The caller must alter this + * if he has a better idea. */ - plan->plan_rows *= 0.1; - if (plan->plan_rows < 1) - plan->plan_rows = 1; plan->state = (EState *) NULL; plan->targetlist = tlist; @@ -1850,8 +1840,8 @@ make_setop(SetOpCmd cmd, List *tlist, Plan *lefttree, plan->total_cost += cpu_operator_cost * plan->plan_rows * numCols; /* - * As for Group, we make the unsupported assumption that there will be - * 10% as many tuples out as in. + * We make the unsupported assumption that there will be 10% as many + * tuples out as in. Any way to do better? */ plan->plan_rows *= 0.1; if (plan->plan_rows < 1) |