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cost_agg really ought to charge something per output tuple; else there 

are cases where it appears to have zero run cost.
This commit is contained in:
Tom Lane 2005-08-27 22:37:00 +00:00
parent 4e5fbb34b3
commit 974e3cf30a
1 changed files with 5 additions and 3 deletions
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8
src/backend/optimizer/path/costsize.c
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@ -49,7 +49,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.146 2005/06/05 22:32:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.147 2005/08/27 22:37:00 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -872,7 +872,7 @@ cost_agg(Path *path, PlannerInfo *root,
* for grouping comparisons.
*
* We will produce a single output tuple if not grouping, and a tuple per
* group otherwise.
* group otherwise. We charge cpu_tuple_cost for each output tuple.
*
* Note: in this cost model, AGG_SORTED and AGG_HASHED have exactly the
* same total CPU cost, but AGG_SORTED has lower startup cost. If the
@ -888,7 +888,7 @@ cost_agg(Path *path, PlannerInfo *root,
startup_cost = input_total_cost;
startup_cost += cpu_operator_cost * (input_tuples + 1) * numAggs;
/* we aren't grouping */
total_cost = startup_cost;
total_cost = startup_cost + cpu_tuple_cost;
}
else if (aggstrategy == AGG_SORTED)
{
@ -899,6 +899,7 @@ cost_agg(Path *path, PlannerInfo *root,
total_cost += cpu_operator_cost * input_tuples * numGroupCols;
total_cost += cpu_operator_cost * input_tuples * numAggs;
total_cost += cpu_operator_cost * numGroups * numAggs;
total_cost += cpu_tuple_cost * numGroups;
}
else
{
@ -908,6 +909,7 @@ cost_agg(Path *path, PlannerInfo *root,
startup_cost += cpu_operator_cost * input_tuples * numAggs;
total_cost = startup_cost;
total_cost += cpu_operator_cost * numGroups * numAggs;
total_cost += cpu_tuple_cost * numGroups;
}
path->startup_cost = startup_cost;