diff options
Diffstat (limited to 'src/backend/commands/tablecmds.c')
| -rw-r--r-- | src/backend/commands/tablecmds.c | 50 |
1 files changed, 49 insertions, 1 deletions
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 97caafbb8e1..ccc25c88f4a 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.91.2.3 2008/05/09 22:38:05 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.91.2.4 2008/05/27 21:14:00 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -398,6 +398,12 @@ TruncateRelation(const RangeVar *relation) errmsg("cannot truncate temporary tables of other sessions"))); /* + * Also check for active uses of the relation in the current + * transaction, including open scans and pending AFTER trigger events. + */ + CheckTableNotInUse(rel, "TRUNCATE"); + + /* * Don't allow truncate on tables which are referenced by foreign keys */ heap_truncate_check_FKs(rel); @@ -1592,6 +1598,48 @@ update_ri_trigger_args(Oid relid, CommandCounterIncrement(); } +/* + * Disallow TRUNCATE (and similar commands) when the current backend has + * any open reference to the target table besides the one just acquired by + * the calling command; this implies there's an open cursor or active plan. + * We need this check because our AccessExclusiveLock doesn't protect us + * against stomping on our own foot, only other people's feet! + * + * We also reject these commands if there are any pending AFTER trigger events + * for the rel. This is certainly necessary for CLUSTER, because it does not + * preserve tuple TIDs and so the pending events would try to fetch the wrong + * tuples. It might be overly cautious in other cases, but again it seems + * better to err on the side of paranoia. + * + * REINDEX calls this with "rel" referencing the index to be rebuilt; here + * we are worried about active indexscans on the index. The trigger-event + * check can be skipped, since we are doing no damage to the parent table. + * + * The statement name (eg, "TRUNCATE") is passed for use in error messages. + */ +void +CheckTableNotInUse(Relation rel, const char *stmt) +{ + int expected_refcnt; + + expected_refcnt = rel->rd_isnailed ? 2 : 1; + if (rel->rd_refcnt != expected_refcnt) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + /* translator: first %s is a SQL command, eg ALTER TABLE */ + errmsg("cannot %s \"%s\" because " + "it is being used by active queries in this session", + stmt, RelationGetRelationName(rel)))); + + if (rel->rd_rel->relkind != RELKIND_INDEX && + AfterTriggerPendingOnRel(RelationGetRelid(rel))) + ereport(ERROR, + (errcode(ERRCODE_OBJECT_IN_USE), + /* translator: first %s is a SQL command, eg ALTER TABLE */ + errmsg("cannot %s \"%s\" because " + "it has pending trigger events", + stmt, RelationGetRelationName(rel)))); +} /* ---------------- * AlterTableAddColumn |