From: Andres Freund <andres@anarazel.de>
Date: Thu, 5 Jul 2018 00:36:01 +0000 (-0700)
Subject: Use context with correct lifetime in hypothetical_dense_rank_final.
X-Git-Tag: REL_12_BETA1~1933
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=249126e761e13c4d8e7519569d483eaeca7dac25;p=postgresql

Use context with correct lifetime in hypothetical_dense_rank_final.

The query lifetime expression context created in
hypothetical_dense_rank_final() was buggily allocated in the calling
memory context. I (Andres) broke that in bf6c614a2f2.

Reported-By: Rajkumar Raghuwanshi
Author: Amit Langote
Discussion:  https://postgr.es/m/CAKcux6kmzWmur5HhA_aU6gYVFu0RLQdgJJ+aC9SLdcOvBSrpfA@mail.gmail.com
Backpatch: 11-
---

diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index ed36851fdd..5867f3df07 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1310,7 +1310,15 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 	osastate = (OSAPerGroupState *) PG_GETARG_POINTER(0);
 	econtext = osastate->qstate->econtext;
 	if (!econtext)
-		osastate->qstate->econtext = econtext = CreateStandaloneExprContext();
+	{
+		MemoryContext oldcontext;
+
+		/* Make sure to we create econtext under correct parent context. */
+		oldcontext = MemoryContextSwitchTo(osastate->qstate->qcontext);
+		osastate->qstate->econtext = CreateStandaloneExprContext();
+		econtext = osastate->qstate->econtext;
+		MemoryContextSwitchTo(oldcontext);
+	}
 
 	/* Adjust nargs to be the number of direct (or aggregated) args */
 	if (nargs % 2 != 0)
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index 10d6bb6824..a120dd83f7 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -2092,3 +2092,12 @@ SELECT variance(unique1::int4), sum(unique1::int8) FROM tenk1;
 (1 row)
 
 ROLLBACK;
+-- test coverage for dense_rank
+SELECT dense_rank(x) WITHIN GROUP (ORDER BY x) FROM (VALUES (1),(1),(2),(2),(3),(3)) v(x) GROUP BY (x) ORDER BY 1;
+ dense_rank 
+------------
+          1
+          1
+          1
+(3 rows)
+
diff --git a/src/test/regress/sql/aggregates.sql b/src/test/regress/sql/aggregates.sql
index 1b6db50956..7e77467ecd 100644
--- a/src/test/regress/sql/aggregates.sql
+++ b/src/test/regress/sql/aggregates.sql
@@ -925,3 +925,6 @@ EXPLAIN (COSTS OFF)
 SELECT variance(unique1::int4), sum(unique1::int8) FROM tenk1;
 
 ROLLBACK;
+
+-- test coverage for dense_rank
+SELECT dense_rank(x) WITHIN GROUP (ORDER BY x) FROM (VALUES (1),(1),(2),(2),(3),(3)) v(x) GROUP BY (x) ORDER BY 1;