ExecuteTruncate quirk: expects a unique list of relations
Hi,
Consider this simple case:
postgres=# TRUNCATE foo, foo;
ERROR: cannot TRUNCATE "foo" because it is being used by active queries in
this session
The above occurs because the ExecuteTruncate() function invokes
truncate_check_rel() in a loop. Since the same table name appears twice, the
rd_refcnt for table "foo" is bumped up to 2, causing the above failure.
We might want to add a step to ExecuteTruncate(), or whatever calls it, to
make the list unique.
Regards,
Nikhils
--
EnterpriseDB http://www.enterprisedb.com
Nikhils wrote:
Hi,
Consider this simple case:
postgres=# TRUNCATE foo, foo;
ERROR: cannot TRUNCATE "foo" because it is being used by active queries in
this sessionThe above occurs because the ExecuteTruncate() function invokes
truncate_check_rel() in a loop. Since the same table name appears twice, the
rd_refcnt for table "foo" is bumped up to 2, causing the above failure.We might want to add a step to ExecuteTruncate(), or whatever calls it, to
make the list unique.
Fixed with attached, applied patch. I didn't see any other cases that
need fixing; LOCK foo, foo already works fine.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
Attachments:
/rtmp/difftext/x-diffDownload
Index: src/backend/commands/tablecmds.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v
retrieving revision 1.259
diff -c -c -r1.259 tablecmds.c
*** src/backend/commands/tablecmds.c 19 Jun 2008 00:46:04 -0000 1.259
--- src/backend/commands/tablecmds.c 16 Jul 2008 16:35:28 -0000
***************
*** 762,767 ****
--- 762,770 ----
ResultRelInfo *resultRelInfo;
ListCell *cell;
+ /* make list unique */
+ stmt->relations = list_union(NIL, stmt->relations);
+
/*
* Open, exclusive-lock, and check all the explicitly-specified relations
*/