Function AfterTriggerPendingOnRel

src/backend/commands/trigger.c:5659–5703

---------- * 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 b

 * ----------
 */
bool
AfterTriggerPendingOnRel(Oid relid)
{
	AfterTriggerEvent event;
	AfterTriggerEventChunk *chunk;
	int			depth;

	/* Scan queued events */
	for_each_event_chunk(event, chunk, afterTriggers.events)
	{
		AfterTriggerShared evtshared = GetTriggerSharedData(event);

		/*
		 * 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_flags & AFTER_TRIGGER_DONE)
			continue;

		if (evtshared->ats_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 < afterTriggers.maxquerydepth; depth++)
	{
		for_each_event_chunk(event, chunk, afterTriggers.query_stack[depth].events)
		{
			AfterTriggerShared evtshared = GetTriggerSharedData(event);

			if (event->ate_flags & AFTER_TRIGGER_DONE)
				continue;

			if (evtshared->ats_relid == relid)
				return true;
		}
	}

	return false;
}


/* ----------