diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index f6b52109fe..bc03ef6033 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.352 2009/03/31 17:59:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.353 2009/04/19 19:46:32 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -1621,7 +1621,7 @@ StoreRelCheck(Relation rel, char *ccname, Node *expr,
 	 * in check constraints; it would fail to examine the contents of
 	 * subselects.
 	 */
-	varList = pull_var_clause(expr, false);
+	varList = pull_var_clause(expr, PVC_REJECT_PLACEHOLDERS);
 	keycount = list_length(varList);
 
 	if (keycount > 0)
@@ -1915,7 +1915,7 @@ AddRelationNewConstraints(Relation rel,
 			List	   *vars;
 			char	   *colname;
 
-			vars = pull_var_clause(expr, false);
+			vars = pull_var_clause(expr, PVC_REJECT_PLACEHOLDERS);
 
 			/* eliminate duplicates */
 			vars = list_union(NIL, vars);
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index a172c5de7a..fee9b8fac8 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.181 2009/03/10 20:58:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.182 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1122,7 +1122,7 @@ qual_is_pushdown_safe(Query *subquery, Index rti, Node *qual,
 	 * Examine all Vars used in clause; since it's a restriction clause, all
 	 * such Vars must refer to subselect output columns.
 	 */
-	vars = pull_var_clause(qual, true);
+	vars = pull_var_clause(qual, PVC_INCLUDE_PLACEHOLDERS);
 	foreach(vl, vars)
 	{
 		Var		   *var = (Var *) lfirst(vl);
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c
index bc4544e5e0..17c9539679 100644
--- a/src/backend/optimizer/path/equivclass.c
+++ b/src/backend/optimizer/path/equivclass.c
@@ -10,7 +10,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.17 2009/02/06 23:43:23 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.18 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -689,7 +689,8 @@ generate_base_implied_equalities_no_const(PlannerInfo *root,
 	foreach(lc, ec->ec_members)
 	{
 		EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc);
-		List	   *vars = pull_var_clause((Node *) cur_em->em_expr, true);
+		List	   *vars = pull_var_clause((Node *) cur_em->em_expr,
+										   PVC_INCLUDE_PLACEHOLDERS);
 
 		add_vars_to_targetlist(root, vars, ec->ec_relids);
 		list_free(vars);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index cff0424c6c..1a957ac396 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.257 2009/03/26 17:15:35 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.258 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3022,7 +3022,8 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
 					if (em->em_is_const || em->em_is_child)
 						continue;
 					sortexpr = em->em_expr;
-					exprvars = pull_var_clause((Node *) sortexpr, true);
+					exprvars = pull_var_clause((Node *) sortexpr,
+											   PVC_INCLUDE_PLACEHOLDERS);
 					foreach(k, exprvars)
 					{
 						if (!tlist_member_ignore_relabel(lfirst(k), tlist))
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index 952fd7649f..dd73beb759 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.150 2009/04/16 20:42:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.151 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -130,7 +130,8 @@ add_base_rels_to_query(PlannerInfo *root, Node *jtnode)
 void
 build_base_rel_tlists(PlannerInfo *root, List *final_tlist)
 {
-	List	   *tlist_vars = pull_var_clause((Node *) final_tlist, true);
+	List	   *tlist_vars = pull_var_clause((Node *) final_tlist,
+											 PVC_INCLUDE_PLACEHOLDERS);
 
 	if (tlist_vars != NIL)
 	{
@@ -981,7 +982,7 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
 	 */
 	if (bms_membership(relids) == BMS_MULTIPLE)
 	{
-		List	   *vars = pull_var_clause(clause, true);
+		List	   *vars = pull_var_clause(clause, PVC_INCLUDE_PLACEHOLDERS);
 
 		add_vars_to_targetlist(root, vars, relids);
 		list_free(vars);
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index d7a793ba76..bf1142aec0 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.253 2009/03/30 17:30:44 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.254 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2236,7 +2236,7 @@ make_subplanTargetList(PlannerInfo *root,
 	 * and window specifications.
 	 */
 	sub_tlist = flatten_tlist(tlist);
-	extravars = pull_var_clause(parse->havingQual, true);
+	extravars = pull_var_clause(parse->havingQual, PVC_INCLUDE_PLACEHOLDERS);
 	sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
 	list_free(extravars);
 	*need_tlist_eval = false;	/* only eval if not flat tlist */
diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
index e6bd43f7b3..73a158e5d8 100644
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -16,7 +16,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.95 2009/01/01 17:23:44 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.96 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -193,7 +193,8 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 		List	   *vars;
 		ListCell   *l;
 
-		vars = pull_var_clause((Node *) parse->returningList, true);
+		vars = pull_var_clause((Node *) parse->returningList,
+							   PVC_INCLUDE_PLACEHOLDERS);
 		foreach(l, vars)
 		{
 			Var		   *var = (Var *) lfirst(l);
diff --git a/src/backend/optimizer/util/placeholder.c b/src/backend/optimizer/util/placeholder.c
index c1834a1291..019352158d 100644
--- a/src/backend/optimizer/util/placeholder.c
+++ b/src/backend/optimizer/util/placeholder.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/placeholder.c,v 1.3 2009/01/01 17:23:45 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/placeholder.c,v 1.4 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -162,7 +162,7 @@ fix_placeholder_eval_levels(PlannerInfo *root)
 		if (bms_membership(eval_at) == BMS_MULTIPLE)
 		{
 			List	   *vars = pull_var_clause((Node *) phinfo->ph_var->phexpr,
-											   true);
+											   PVC_INCLUDE_PLACEHOLDERS);
 
 			add_vars_to_targetlist(root, vars, eval_at);
 			list_free(vars);
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 5cf2839b37..9526aefd9a 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/tlist.c,v 1.85 2009/01/01 17:23:45 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/tlist.c,v 1.86 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -91,7 +91,8 @@ tlist_member_ignore_relabel(Node *node, List *targetlist)
 List *
 flatten_tlist(List *tlist)
 {
-	List	   *vlist = pull_var_clause((Node *) tlist, true);
+	List	   *vlist = pull_var_clause((Node *) tlist,
+										PVC_INCLUDE_PLACEHOLDERS);
 	List	   *new_tlist;
 
 	new_tlist = add_to_flat_tlist(NIL, vlist);
diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index 7768712b56..cd88c337f1 100644
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.84 2009/02/25 03:30:37 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/util/var.c,v 1.85 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -56,7 +56,7 @@ typedef struct
 typedef struct
 {
 	List	   *varlist;
-	bool		includePlaceHolderVars;
+	PVCPlaceHolderBehavior behavior;
 } pull_var_clause_context;
 
 typedef struct
@@ -614,11 +614,13 @@ find_minimum_var_level_walker(Node *node,
  * pull_var_clause
  *	  Recursively pulls all Var nodes from an expression clause.
  *
- *	  PlaceHolderVars are included too, if includePlaceHolderVars is true.
- *	  If it isn't true, an error is thrown if any are found.
- *	  Note that Vars within a PHV's expression are *not* included.
+ *	  PlaceHolderVars are handled according to 'behavior':
+ *		PVC_REJECT_PLACEHOLDERS		throw error if PlaceHolderVar found
+ *		PVC_INCLUDE_PLACEHOLDERS	include PlaceHolderVars in output list
+ *		PVC_RECURSE_PLACEHOLDERS	recurse into PlaceHolderVar argument
+ *	  Vars within a PHV's expression are included only in the last case.
  *
- *	  CurrentOfExpr nodes are *not* included.
+ *	  CurrentOfExpr nodes are ignored in all cases.
  *
  *	  Upper-level vars (with varlevelsup > 0) are not included.
  *	  (These probably represent errors too, but we don't complain.)
@@ -630,12 +632,12 @@ find_minimum_var_level_walker(Node *node,
  * of sublinks to subplans!
  */
 List *
-pull_var_clause(Node *node, bool includePlaceHolderVars)
+pull_var_clause(Node *node, PVCPlaceHolderBehavior behavior)
 {
 	pull_var_clause_context context;
 
 	context.varlist = NIL;
-	context.includePlaceHolderVars = includePlaceHolderVars;
+	context.behavior = behavior;
 
 	pull_var_clause_walker(node, &context);
 	return context.varlist;
@@ -654,12 +656,20 @@ pull_var_clause_walker(Node *node, pull_var_clause_context *context)
 	}
 	if (IsA(node, PlaceHolderVar))
 	{
-		if (!context->includePlaceHolderVars)
-			elog(ERROR, "PlaceHolderVar found where not expected");
-		if (((PlaceHolderVar *) node)->phlevelsup == 0)
-			context->varlist = lappend(context->varlist, node);
-		/* we do NOT descend into the contained expression */
-		return false;
+		switch (context->behavior)
+		{
+			case PVC_REJECT_PLACEHOLDERS:
+				elog(ERROR, "PlaceHolderVar found where not expected");
+				break;
+			case PVC_INCLUDE_PLACEHOLDERS:
+				if (((PlaceHolderVar *) node)->phlevelsup == 0)
+					context->varlist = lappend(context->varlist, node);
+				/* we do NOT descend into the contained expression */
+				return false;
+			case PVC_RECURSE_PLACEHOLDERS:
+				/* ignore the placeholder, look at its argument instead */
+				break;
+		}
 	}
 	return expression_tree_walker(node, pull_var_clause_walker,
 								  (void *) context);
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index e4b1acb1f8..3f07db6857 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.259 2009/02/15 20:16:21 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.260 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2984,9 +2984,12 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows)
 		ReleaseVariableStats(vardata);
 
 		/*
-		 * Else pull out the component Vars
+		 * Else pull out the component Vars.  Handle PlaceHolderVars by
+		 * recursing into their arguments (effectively assuming that the
+		 * PlaceHolderVar doesn't change the number of groups, which boils
+		 * down to ignoring the possible addition of nulls to the result set).
 		 */
-		varshere = pull_var_clause(groupexpr, true);
+		varshere = pull_var_clause(groupexpr, PVC_RECURSE_PLACEHOLDERS);
 
 		/*
 		 * If we find any variable-free GROUP BY item, then either it is a
diff --git a/src/include/optimizer/var.h b/src/include/optimizer/var.h
index 83b181932e..5d19572e0d 100644
--- a/src/include/optimizer/var.h
+++ b/src/include/optimizer/var.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/var.h,v 1.40 2009/01/01 17:24:00 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/var.h,v 1.41 2009/04/19 19:46:33 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,6 +16,12 @@
 
 #include "nodes/relation.h"
 
+typedef enum
+{
+	PVC_REJECT_PLACEHOLDERS,	/* throw error if PlaceHolderVar found */
+	PVC_INCLUDE_PLACEHOLDERS,	/* include PlaceHolderVars in output list */
+	PVC_RECURSE_PLACEHOLDERS	/* recurse into PlaceHolderVar argument */
+} PVCPlaceHolderBehavior;
 
 extern Relids pull_varnos(Node *node);
 extern void pull_varattnos(Node *node, Bitmapset **varattnos);
@@ -24,7 +30,7 @@ extern bool contain_vars_of_level(Node *node, int levelsup);
 extern int	locate_var_of_level(Node *node, int levelsup);
 extern int	locate_var_of_relation(Node *node, int relid, int levelsup);
 extern int	find_minimum_var_level(Node *node);
-extern List *pull_var_clause(Node *node, bool includePlaceHolderVars);
+extern List *pull_var_clause(Node *node, PVCPlaceHolderBehavior behavior);
 extern Node *flatten_join_alias_vars(PlannerInfo *root, Node *node);
 
 #endif   /* VAR_H */