Fix AfterTriggerSaveEvent to use a test and elog, not just Assert, to check

that it's called within an AfterTriggerBeginQuery/AfterTriggerEndQuery pair.
The RI cascade triggers suppress that overhead on the assumption that they
are always run non-deferred, so it's possible to violate the condition if
someone mistakenly changes pg_trigger to mark such a trigger deferred.
We don't really care about supporting that, but throwing an error instead
of crashing seems desirable.  Per report from Marcelo Costa.

diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index cdd545eeaa6f7ef0d4ef6c078b255a11bb7e7b2d..885c34d8347151672ee044f97d6b02fddc631b9b 100644 (file)
--- 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 1.255 2009/10/26 02:26:28 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/trigger.c,v 1.256 2009/10/27 20:14:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3895,9 +3895,15 @@ AfterTriggerSaveEvent(ResultRelInfo *relinfo, int event, bool row_trigger,
        int                     ntriggers;
        int                *tgindx;
 
+       /*
+        * Check state.  We use normal tests not Asserts because it is possible
+        * to reach here in the wrong state given misconfigured RI triggers,
+        * in particular deferring a cascade action trigger.
+        */
        if (afterTriggers == NULL)
                elog(ERROR, "AfterTriggerSaveEvent() called outside of transaction");
-       Assert(afterTriggers->query_depth >= 0);
+       if (afterTriggers->query_depth < 0)
+               elog(ERROR, "AfterTriggerSaveEvent() called outside of query");
 
        /*
         * Validate the event code and collect the associated tuple CTIDs.