From f0f18c7087e04a60e2612151401b07df87e51d96 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 30 Nov 2007 18:38:34 +0000
Subject: [PATCH] Repair bug that allowed RevalidateCachedPlan to attempt to
rebuild a cached plan before the effects of DDL executed in an immediately
prior SPI operation had been absorbed. Per report from Chris Wood.
This patch has an unpleasant side effect of causing the number of
CommandCounterIncrement()s done by a typical plpgsql function to
approximately double. Amelioration of the consequences of that
will be undertaken in a separate patch.
---
src/backend/executor/spi.c | 18 +++++------
src/test/regress/expected/plancache.out | 40 +++++++++++++++++++++++++
src/test/regress/sql/plancache.sql | 19 ++++++++++++
3 files changed, 68 insertions(+), 9 deletions(-)
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 3d72fa20a55..a5601ecdfca 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.184 2007/11/15 21:14:35 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.185 2007/11/30 18:38:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1374,14 +1374,6 @@ _SPI_prepare_plan(const char *src, SPIPlanPtr plan)
int nargs = plan->nargs;
int cursor_options = plan->cursor_options;
- /*
- * Increment CommandCounter to see changes made by now. We must do this
- * to be sure of seeing any schema changes made by a just-preceding SPI
- * command. (But we don't bother advancing the snapshot, since the
- * planner generally operates under SnapshotNow rules anyway.)
- */
- CommandCounterIncrement();
-
/*
* Setup error traceback support for ereport()
*/
@@ -1662,6 +1654,14 @@ _SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
if (cplan)
ReleaseCachedPlan(cplan, true);
cplan = NULL;
+
+ /*
+ * If not read-only mode, advance the command counter after the
+ * last command. This ensures that its effects are visible, in
+ * case it was DDL that would affect the next CachedPlanSource.
+ */
+ if (!read_only)
+ CommandCounterIncrement();
}
fail:
diff --git a/src/test/regress/expected/plancache.out b/src/test/regress/expected/plancache.out
index d7d7be92529..7ee11921c25 100644
--- a/src/test/regress/expected/plancache.out
+++ b/src/test/regress/expected/plancache.out
@@ -202,6 +202,7 @@ drop schema s1 cascade;
NOTICE: drop cascades to table s1.abc
drop schema s2 cascade;
NOTICE: drop cascades to table abc
+reset search_path;
-- Check that invalidation deals with regclass constants
create temp sequence seq;
prepare p2 as select nextval('seq');
@@ -219,3 +220,42 @@ execute p2;
1
(1 row)
+-- Check DDL via SPI, immediately followed by SPI plan re-use
+-- (bug in original coding)
+create function cachebug() returns void as $$
+declare r int;
+begin
+ drop table if exists temptable cascade;
+ create temp table temptable as select * from generate_series(1,3) as f1;
+ create temp view vv as select * from temptable;
+ for r in select * from vv loop
+ raise notice '%', r;
+ end loop;
+end$$ language plpgsql;
+select cachebug();
+NOTICE: table "temptable" does not exist, skipping
+CONTEXT: SQL statement "drop table if exists temptable cascade"
+PL/pgSQL function "cachebug" line 3 at SQL statement
+NOTICE: 1
+NOTICE: 2
+NOTICE: 3
+ cachebug
+----------
+
+(1 row)
+
+select cachebug();
+NOTICE: drop cascades to rule _RETURN on view vv
+CONTEXT: SQL statement "drop table if exists temptable cascade"
+PL/pgSQL function "cachebug" line 3 at SQL statement
+NOTICE: drop cascades to view vv
+CONTEXT: SQL statement "drop table if exists temptable cascade"
+PL/pgSQL function "cachebug" line 3 at SQL statement
+NOTICE: 1
+NOTICE: 2
+NOTICE: 3
+ cachebug
+----------
+
+(1 row)
+
diff --git a/src/test/regress/sql/plancache.sql b/src/test/regress/sql/plancache.sql
index fc57279d985..26848168f06 100644
--- a/src/test/regress/sql/plancache.sql
+++ b/src/test/regress/sql/plancache.sql
@@ -124,6 +124,8 @@ execute p1;
drop schema s1 cascade;
drop schema s2 cascade;
+reset search_path;
+
-- Check that invalidation deals with regclass constants
create temp sequence seq;
@@ -137,3 +139,20 @@ drop sequence seq;
create temp sequence seq;
execute p2;
+
+-- Check DDL via SPI, immediately followed by SPI plan re-use
+-- (bug in original coding)
+
+create function cachebug() returns void as $$
+declare r int;
+begin
+ drop table if exists temptable cascade;
+ create temp table temptable as select * from generate_series(1,3) as f1;
+ create temp view vv as select * from temptable;
+ for r in select * from vv loop
+ raise notice '%', r;
+ end loop;
+end$$ language plpgsql;
+
+select cachebug();
+select cachebug();
--
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