diff options
Diffstat (limited to 'src/backend/commands/trigger.c')
| -rw-r--r-- | src/backend/commands/trigger.c | 66 |
1 files changed, 65 insertions, 1 deletions
diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c index 9510f849006..276efb8477e 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 1.195.2.4 2007/08/15 19:16:03 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.195.2.5 2008/05/27 21:13:39 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -3062,6 +3062,70 @@ AfterTriggerSetState(ConstraintsSetStmt *stmt) } } +/* ---------- + * AfterTriggerPendingOnRel() + * Test to see if there are any pending after-trigger events for rel. + * + * This is used by TRUNCATE, CLUSTER, ALTER TABLE, etc to detect whether + * it is unsafe to perform major surgery on a relation. Note that only + * local pending events are examined. We assume that having exclusive lock + * on a rel guarantees there are no unserviced events in other backends --- + * but having a lock does not prevent there being such events in our own. + * + * In some scenarios it'd be reasonable to remove pending events (more + * specifically, mark them DONE by the current subxact) but without a lot + * of knowledge of the trigger semantics we can't do this in general. + * ---------- + */ +bool +AfterTriggerPendingOnRel(Oid relid) +{ + AfterTriggerEvent event; + int depth; + + /* No-op if we aren't in a transaction. (Shouldn't happen?) */ + if (afterTriggers == NULL) + return false; + + /* Scan queued events */ + for (event = afterTriggers->events.head; + event != NULL; + event = event->ate_next) + { + /* + * We can ignore completed events. (Even if a DONE flag is rolled + * back by subxact abort, it's OK because the effects of the TRUNCATE + * or whatever must get rolled back too.) + */ + if (event->ate_event & AFTER_TRIGGER_DONE) + continue; + + if (event->ate_relid == relid) + return true; + } + + /* + * Also scan events queued by incomplete queries. This could only matter + * if TRUNCATE/etc is executed by a function or trigger within an updating + * query on the same relation, which is pretty perverse, but let's check. + */ + for (depth = 0; depth <= afterTriggers->query_depth; depth++) + { + for (event = afterTriggers->query_stack[depth].head; + event != NULL; + event = event->ate_next) + { + if (event->ate_event & AFTER_TRIGGER_DONE) + continue; + + if (event->ate_relid == relid) + return true; + } + } + + return false; +} + /* ---------- * AfterTriggerSaveEvent() |