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

tglsfdc · tglsfdc · commit 974e3cf30afe · 2005-08-27T22:37:00.000Z
are cases where it appears to have zero run cost.
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
@@ -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;

Original file line number	Diff line number	Diff line change
`@@ -49,7 +49,7 @@`
`49`	`49`	`* Portions Copyright (c) 1994, Regents of the University of California`
`50`	`50`	`*`
`51`	`51`	`* IDENTIFICATION`
`52`		`- * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.146 2005/06/05 22:32:55 tgl Exp $`
	`52`	`+ * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.147 2005/08/27 22:37:00 tgl Exp $`
`53`	`53`	`*`
`54`	`54`	`*-------------------------------------------------------------------------`
`55`	`55`	`*/`
`@@ -872,7 +872,7 @@ cost_agg(Path path, PlannerInfo root,`
`872`	`872`	`* for grouping comparisons.`
`873`	`873`	`*`
`874`	`874`	`* We will produce a single output tuple if not grouping, and a tuple per`
`875`		`- * group otherwise.`
	`875`	`+ * group otherwise. We charge cpu_tuple_cost for each output tuple.`
`876`	`876`	`*`
`877`	`877`	`* Note: in this cost model, AGG_SORTED and AGG_HASHED have exactly the`
`878`	`878`	`* same total CPU cost, but AGG_SORTED has lower startup cost. If the`
`@@ -888,7 +888,7 @@ cost_agg(Path path, PlannerInfo root,`
`888`	`888`	`startup_cost = input_total_cost;`
`889`	`889`	`startup_cost += cpu_operator_cost * (input_tuples + 1) * numAggs;`
`890`	`890`	`/* we aren't grouping */`
`891`		`- total_cost = startup_cost;`
	`891`	`+ total_cost = startup_cost + cpu_tuple_cost;`
`892`	`892`	`}`
`893`	`893`	`else if (aggstrategy == AGG_SORTED)`
`894`	`894`	`{`
`@@ -899,6 +899,7 @@ cost_agg(Path path, PlannerInfo root,`
`899`	`899`	`total_cost += cpu_operator_cost * input_tuples * numGroupCols;`
`900`	`900`	`total_cost += cpu_operator_cost * input_tuples * numAggs;`
`901`	`901`	`total_cost += cpu_operator_cost * numGroups * numAggs;`
	`902`	`+ total_cost += cpu_tuple_cost * numGroups;`
`902`	`903`	`}`
`903`	`904`	`else`
`904`	`905`	`{`
`@@ -908,6 +909,7 @@ cost_agg(Path path, PlannerInfo root,`
`908`	`909`	`startup_cost += cpu_operator_cost * input_tuples * numAggs;`
`909`	`910`	`total_cost = startup_cost;`
`910`	`911`	`total_cost += cpu_operator_cost * numGroups * numAggs;`
	`912`	`+ total_cost += cpu_tuple_cost * numGroups;`
`911`	`913`	`}`
`912`	`914`
`913`	`915`	`path->startup_cost = startup_cost;`