Re: ON DELETE CASCADE with multiple paths

Stephan Szabo wrote:
> On Thu, 17 May 2007, Tom Lane wrote:
> 
>> Max Khon  writes:
>>> "delete from foo" fails:
>>> ERROR: update or delete on table "bar" violates foreign key constraint
>>> "foobar_fk0" on table "foobar"
>>> SQL state: 23503
>>> Detail: Key (bar_id)=(1) is still referenced from table "foobar".
>>> Context: SQL statement "DELETE FROM ONLY "public"."bar" WHERE "foo_id" = $1"
>> I see no bug here.  There is no guarantee about the order in which
>> constraints are applied.
> 
> Except that SQL92 at least does seem to say in 11.8 that "All rows that
> are marked for deletion are effectively deleted at the end of the
> SQL-statement, prior to the checking of any integrity constraints." I
> think that likely makes our behavior wrong, but I'm not really sure how to
> get there from what we have now.

Is it sufficient to execute ON DELETE CASCADE and ON DELETE SET
NULL/DEFAULT triggers before other triggers?

Attached patch solves the problem for me.

-- 
Max Khon
PEM Platform Team Leader
SWsoft, Inc.
E-mail: mkhon@swsoft.com
Web Site: http://swsoft.com/
--- src/backend/commands/trigger.c.orig	2007-05-21 15:45:53.000000000 +0700
+++ src/backend/commands/trigger.c	2007-05-21 15:51:42.000000000 +0700
@@ -1989,6 +1989,24 @@
 }
 
 
+static bool
+afterTriggerCascadeOrSetXXX(Oid tgfoid)
+{
+	switch (tgfoid)
+	{
+		case F_RI_FKEY_CASCADE_DEL:
+		case F_RI_FKEY_CASCADE_UPD:
+		case F_RI_FKEY_SETNULL_DEL:
+		case F_RI_FKEY_SETNULL_UPD:
+		case F_RI_FKEY_SETDEFAULT_DEL:
+		case F_RI_FKEY_SETDEFAULT_UPD:
+			return true;
+
+		default:
+			return false;
+	}
+}
+
 /* ----------
  * afterTriggerAddEvent()
  *
@@ -1996,7 +2014,7 @@
  * ----------
  */
 static void
-afterTriggerAddEvent(AfterTriggerEvent event)
+afterTriggerAddEvent(AfterTriggerEvent event, Oid tgfoid)
 {
 	AfterTriggerEventList *events;
 
@@ -2012,6 +2030,11 @@
 		events->head = event;
 		events->tail = event;
 	}
+	else if (afterTriggerCascadeOrSetXXX(tgfoid))
+	{
+		event->ate_next = events->head;
+		events->head = event;
+	}
 	else
 	{
 		events->tail->ate_next = event;
@@ -3178,6 +3201,6 @@
 		/*
 		 * Add the new event to the queue.
 		 */
-		afterTriggerAddEvent(new_event);
+		afterTriggerAddEvent(new_event, trigger->tgfoid);
 	}
 }