Stopgap solution for problem reported by Alexey Beschiokov: after

doing heap_insert or heap_update, wipe out any extracted fields in
the TupleTableSlot containing the tuple, because they might not be valid
anymore if tuptoaster.c changed the tuple.  Safe because slot must be
in the materialized state, but mighty ugly --- find a better answer!

src/backend/executor/execMain.c

@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.258 2005/11/18 12:26:20 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.259 2005/11/19 20:57:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1445,6 +1445,16 @@ ExecInsert(TupleTableSlot *slot,
 	estate->es_lastoid = newId;
 	setLastTid(&(tuple->t_self));
 
+	/*
+	 * KLUGE SOLUTION for bug found post 8.1 release: if the tuple toaster
+	 * fired on the tuple then it changed the physical tuple inside the
+	 * tuple slot, leaving any extracted information invalid.  Mark the
+	 * extracted state invalid just in case.  Need to fix things so that
+	 * the toaster gets to run against the tuple before we materialize it,
+	 * but that's way too invasive for a stable branch.
+	 */
+	slot->tts_nvalid = 0;
+
 	/*
 	 * insert index entries for tuple
 	 */
@@ -1547,11 +1557,11 @@ ldelete:;
 
 	/*
 	 * Note: Normally one would think that we have to delete index tuples
-	 * associated with the heap tuple now..
+	 * associated with the heap tuple now...
 	 *
-	 * ... but in POSTGRES, we have no need to do this because the vacuum daemon
-	 * automatically opens an index scan and deletes index tuples when it
-	 * finds deleted heap tuples. -cim 9/27/89
+	 * ... but in POSTGRES, we have no need to do this because VACUUM will
+	 * take care of it later.  We can't delete index tuples immediately
+	 * anyway, since the tuple is still visible to other transactions.
 	 */
 
 	/* AFTER ROW DELETE Triggers */
@@ -1699,12 +1709,22 @@ lreplace:;
 	IncrReplaced();
 	(estate->es_processed)++;
 
+	/*
+	 * KLUGE SOLUTION for bug found post 8.1 release: if the tuple toaster
+	 * fired on the tuple then it changed the physical tuple inside the
+	 * tuple slot, leaving any extracted information invalid.  Mark the
+	 * extracted state invalid just in case.  Need to fix things so that
+	 * the toaster gets to run against the tuple before we materialize it,
+	 * but that's way too invasive for a stable branch.
+	 */
+	slot->tts_nvalid = 0;
+
 	/*
 	 * Note: instead of having to update the old index tuples associated with
 	 * the heap tuple, all we do is form and insert new index tuples. This is
 	 * because UPDATEs are actually DELETEs and INSERTs, and index tuple
-	 * deletion is done automagically by the vacuum daemon. All we do is
-	 * insert new index tuples.  -cim 9/27/89
+	 * deletion is done later by VACUUM (see notes in ExecDelete).  All we do
+	 * here is insert new index tuples.  -cim 9/27/89
 	 */
 
 	/*