Ensure that the phrels sets of PlaceHolderVars appearing in an AppendRelInfo's

translated_vars list get updated when pulling up an appendrel member.  It's
not clear that this really matters at present, since relatively little gets
done with the outputs of an appendrel child relation; but it probably will
come back to bite us sometime if we leave them with the wrong values.

src/backend/optimizer/prep/prepjointree.c

@@ -16,7 +16,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.59 2008/11/11 18:13:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.60 2008/11/11 19:05:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -709,10 +709,9 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	 * insert_targetlist_placeholders() will be adjusted, so having created
 	 * them with the subquery's varno is correct.
 	 *
-	 * Likewise, relids appearing in AppendRelInfo nodes have to be fixed (but
-	 * we took care of their translated_vars lists above).	We already checked
-	 * that this won't require introducing multiple subrelids into the
-	 * single-slot AppendRelInfo structs.
+	 * Likewise, relids appearing in AppendRelInfo nodes have to be fixed.
+	 * We already checked that this won't require introducing multiple
+	 * subrelids into the single-slot AppendRelInfo structs.
 	 */
 	if (parse->hasSubLinks || root->glob->lastPHId != 0 ||
 		root->append_rel_list)
@@ -1679,7 +1678,8 @@ substitute_multiple_relids(Node *node, int varno, Relids subrelids)
  *
  * When we pull up a subquery, any AppendRelInfo references to the subquery's
  * RT index have to be replaced by the substituted relid (and there had better
- * be only one).
+ * be only one).  We also need to apply substitute_multiple_relids to their
+ * translated_vars lists, since those might contain PlaceHolderVars.
  *
  * We assume we may modify the AppendRelInfo nodes in-place.
  */
@@ -1708,6 +1708,10 @@ fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids)
 				subvarno = bms_singleton_member(subrelids);
 			appinfo->child_relid = subvarno;
 		}
+
+		/* Also finish fixups for its translated vars */
+		substitute_multiple_relids((Node *) appinfo->translated_vars,
+								   varno, subrelids);
 	}
 }