From 4886dc92e0a45e50600187e7ff8e289e14ded5ca Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 10 Mar 2009 20:58:26 +0000
Subject: [PATCH] Fix set_subquery_pathlist() to copy the RTE's subquery before
it gets mangled by the planning process. This prevents the "failed to locate
grouping columns" error recently reported by Dickson Guedes. That happens
because planning replaces SubLinks by SubPlans in the subquery's targetlist,
and exprTypmod() is smarter about the former than the latter, causing the
apparent type of the subquery's output columns to change. This seems to be a
deficiency we should fix in exprTypmod(), but that will be a much more
invasive patch with possible side-effects elsewhere, so I'll do that only in
HEAD.
Back-patch to 8.3. Arguably the lack of a copying step is broken/dangerous
all the way back, but in the absence of known problems I'll refrain from
making the older branches pay the extra cost. (The reason this particular
symptom didn't appear before is that exprTypmod() wasn't smart about SubLinks
either, until 8.3.)
---
src/backend/optimizer/path/allpaths.c | 9 ++++++++-
src/test/regress/expected/subselect.out | 12 ++++++++++++
src/test/regress/sql/subselect.sql | 11 +++++++++++
3 files changed, 31 insertions(+), 1 deletion(-)
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 4e0d9ca4e57..a172c5de7ab 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.180 2009/02/15 20:16:21 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.181 2009/03/10 20:58:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -523,6 +523,13 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
PlannerInfo *subroot;
List *pathkeys;
+ /*
+ * Must copy the Query so that planning doesn't mess up the RTE contents
+ * (really really need to fix the planner to not scribble on its input,
+ * someday).
+ */
+ subquery = copyObject(subquery);
+
/* We need a workspace for keeping track of set-op type coercions */
differentTypes = (bool *)
palloc0((list_length(subquery->targetList) + 1) * sizeof(bool));
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index f6dbc0212cd..49ee53741b2 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -465,3 +465,15 @@ from tc;
3
(2 rows)
+--
+-- Test case for 8.3 "failed to locate grouping columns" bug
+--
+create temp table t1 (f1 numeric(14,0), f2 varchar(30));
+select * from
+ (select distinct f1, f2, (select f2 from t1 x where x.f1 = up.f1) as fs
+ from t1 up) ss
+group by f1,f2,fs;
+ f1 | f2 | fs
+----+----+----
+(0 rows)
+
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 3a3f11793dc..fd8d5df3a01 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -298,3 +298,14 @@ select
( select min(tb.id) from tb
where tb.aval = (select ta.val from ta where ta.id = tc.aid) ) as min_tb_id
from tc;
+
+--
+-- Test case for 8.3 "failed to locate grouping columns" bug
+--
+
+create temp table t1 (f1 numeric(14,0), f2 varchar(30));
+
+select * from
+ (select distinct f1, f2, (select f2 from t1 x where x.f1 = up.f1) as fs
+ from t1 up) ss
+group by f1,f2,fs;
--
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