From 8cbeb5f131a4339aaf69c34a874922d79c0fe585 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 24 Mar 2000 21:40:43 +0000
Subject: [PATCH] Save a few cycles in simple cases: no need to call
cost_sort() when there is no presorted path to compare with.
---
src/backend/optimizer/plan/planmain.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c
index acc4eb5d938..4377359ddcc 100644
--- a/src/backend/optimizer/plan/planmain.c
+++ b/src/backend/optimizer/plan/planmain.c
@@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.53 2000/03/21 05:11:58 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.54 2000/03/24 21:40:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -174,7 +174,6 @@ subplanner(Query *root,
{
RelOptInfo *final_rel;
Path *cheapestpath;
- Path sort_path; /* dummy for result of cost_sort */
Path *presortedpath;
/*
@@ -288,21 +287,22 @@ subplanner(Query *root,
* cheaper than doing an explicit sort on the cheapest-total-cost path.
*/
cheapestpath = final_rel->cheapest_total_path;
- cost_sort(&sort_path, root->query_pathkeys,
- final_rel->rows, final_rel->width);
- sort_path.startup_cost += cheapestpath->total_cost;
- sort_path.total_cost += cheapestpath->total_cost;
-
presortedpath =
get_cheapest_fractional_path_for_pathkeys(final_rel->pathlist,
root->query_pathkeys,
tuple_fraction);
if (presortedpath)
{
+ Path sort_path; /* dummy for result of cost_sort */
+
+ cost_sort(&sort_path, root->query_pathkeys,
+ final_rel->rows, final_rel->width);
+ sort_path.startup_cost += cheapestpath->total_cost;
+ sort_path.total_cost += cheapestpath->total_cost;
if (compare_fractional_path_costs(presortedpath, &sort_path,
tuple_fraction) <= 0)
{
- /* Found a better presorted path, use it */
+ /* Presorted path is cheaper, use it */
root->query_pathkeys = presortedpath->pathkeys;
return create_plan(root, presortedpath);
}
--
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