From 32fcfcdbd66368c51c5561329d2a003eaff1fd64 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 19 Oct 2005 17:31:20 +0000
Subject: [PATCH] Fix oversight in recent changes to enable the 'physical
tlist' optimization for subquery and function scan nodes: we can't just do it
unconditionally, we still have to check whether there is any need for a
whole-row Var. I had been thinking that these node types couldn't have any
system columns, which is true, but that loop is also checking for attno zero,
ie, whole-row Var. Fix comment to not be so misleading. Per test case from
Richard Huxton.
---
src/backend/optimizer/plan/createplan.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index f0dd6548711..fc093fdf180 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.201 2005/10/15 02:49:20 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.202 2005/10/19 17:31:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -308,17 +308,13 @@ use_physical_tlist(RelOptInfo *rel)
int i;
/*
- * OK for subquery and function scans; otherwise, can't do it for anything
- * except real relations.
+ * We can do this for real relation scans, subquery scans, and function
+ * scans (but not for, eg, joins).
*/
- if (rel->rtekind != RTE_RELATION)
- {
- if (rel->rtekind == RTE_SUBQUERY)
- return true;
- if (rel->rtekind == RTE_FUNCTION)
- return true;
+ if (rel->rtekind != RTE_RELATION &&
+ rel->rtekind != RTE_SUBQUERY &&
+ rel->rtekind != RTE_FUNCTION)
return false;
- }
/*
* Can't do it with inheritance cases either (mainly because Append
@@ -328,15 +324,16 @@ use_physical_tlist(RelOptInfo *rel)
return false;
/*
- * Can't do it if any system columns are requested, either. (This could
- * possibly be fixed but would take some fragile assumptions in setrefs.c,
- * I think.)
+ * Can't do it if any system columns or whole-row Vars are requested,
+ * either. (This could possibly be fixed but would take some fragile
+ * assumptions in setrefs.c, I think.)
*/
for (i = rel->min_attr; i <= 0; i++)
{
if (!bms_is_empty(rel->attr_needed[i - rel->min_attr]))
return false;
}
+
return true;
}
--
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