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If we expect a hash join to be performed in multiple batches, suppress

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"physical tlist" optimization on the outer relation (ie, force a projection
step to occur in its scan).  This avoids storing useless column values when
the outer relation's tuples are written to temporary batch files.

Modified version of a patch by Michael Henderson and Ramon Lawrence.
This commit is contained in:
Tom Lane
2009-03-26 17:15:35 +00:00
parent ee4c187f64
commit f38fbf31f5
5 changed files with 25 additions and 6 deletions
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6
src/backend/optimizer/plan/createplan.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.256 2009/03/21 00:04:39 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.257 2009/03/26 17:15:35 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1910,6 +1910,10 @@ create_hashjoin_plan(PlannerInfo *root,
/* We don't want any excess columns in the hashed tuples */
disuse_physical_tlist(inner_plan, best_path->jpath.innerjoinpath);
/* If we expect batching, suppress excess columns in outer tuples too */
if (best_path->num_batches > 1)
disuse_physical_tlist(outer_plan, best_path->jpath.outerjoinpath);
/*
* If there is a single join clause and we can identify the outer
* variable as a simple column reference, supply its identity for