diff --git a/src/backend/executor/nodeLockRows.c b/src/backend/executor/nodeLockRows.c
index d573853eba9..a84b64b0952 100644
--- a/src/backend/executor/nodeLockRows.c
+++ b/src/backend/executor/nodeLockRows.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeLockRows.c,v 1.5 2010/07/12 17:01:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeLockRows.c,v 1.6 2010/07/28 17:21:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -195,6 +195,13 @@ lnext:
 			HeapTupleData tuple;
 			Buffer		buffer;
 
+			/* ignore non-active child tables */
+			if (!ItemPointerIsValid(&(erm->curCtid)))
+			{
+				Assert(erm->rti != erm->prti);	/* check it's child table */
+				continue;
+			}
+
 			if (EvalPlanQualGetTuple(&node->lr_epqstate, erm->rti) != NULL)
 				continue;		/* it was updated and fetched above */