diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/commands/tablecmds.c | 14 | ||||
| -rw-r--r-- | src/backend/commands/trigger.c | 11 |
2 files changed, 16 insertions, 9 deletions
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 0b11976db84..1a6c1f82625 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.148 2005/03/20 22:00:52 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.149 2005/03/23 07:44:57 neilc Exp $ * *------------------------------------------------------------------------- */ @@ -3829,13 +3829,13 @@ ATAddForeignKeyConstraint(AlteredTableInfo *tab, Relation rel, Oid constrOid; /* - * Grab an exclusive lock on the pk table, so that someone doesn't - * delete rows out from under us. (Although a lesser lock would do for - * that purpose, we'll need exclusive lock anyway to add triggers to - * the pk table; trying to start with a lesser lock will just create a - * risk of deadlock.) + * Grab a lock on the pk table, so that someone doesn't delete + * rows out from under us. We will eventually need to add triggers + * to the table, at which point we'll need to an ExclusiveLock -- + * therefore we grab an ExclusiveLock now to prevent possible + * deadlock. */ - pkrel = heap_openrv(fkconstraint->pktable, AccessExclusiveLock); + pkrel = heap_openrv(fkconstraint->pktable, ExclusiveLock); /* * Validity and permissions checks diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c index fd7d9afb836..55333e1f4f1 100644 --- a/src/backend/commands/trigger.c +++ b/src/backend/commands/trigger.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.178 2005/03/20 23:40:24 neilc Exp $ + * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.179 2005/03/23 07:44:57 neilc Exp $ * *------------------------------------------------------------------------- */ @@ -87,7 +87,14 @@ CreateTrigger(CreateTrigStmt *stmt, bool forConstraint) ObjectAddress myself, referenced; - rel = heap_openrv(stmt->relation, AccessExclusiveLock); + /* + * We need to prevent concurrent CREATE TRIGGER commands, as well + * as concurrent table modifications (INSERT, DELETE, UPDATE), so + * acquire an ExclusiveLock -- it should be fine to allow SELECTs + * to proceed. We could perhaps acquire ShareRowExclusiveLock, but + * there seems little gain in allowing SELECT FOR UPDATE. + */ + rel = heap_openrv(stmt->relation, ExclusiveLock); if (stmt->constrrel != NULL) constrrelid = RangeVarGetRelid(stmt->constrrel, false); |