diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 6b784cd75c..109a014547 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 1.239 2008/04/13 20:51:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.240 2008/04/17 21:22:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -115,6 +115,7 @@ static MergeJoin *make_mergejoin(List *tlist,
 static Sort *make_sort(PlannerInfo *root, Plan *lefttree, int numCols,
 		  AttrNumber *sortColIdx, Oid *sortOperators, bool *nullsFirst,
 		  double limit_tuples);
+static Material *make_material(Plan *lefttree);
 
 
 /*
@@ -616,12 +617,14 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 	 * add any such expressions to the subplan's tlist.
 	 *
 	 * The subplan may have a "physical" tlist if it is a simple scan plan.
-	 * This should be left as-is if we don't need to add any expressions;
+	 * If we're going to sort, this should be reduced to the regular tlist,
+	 * so that we don't sort more data than we need to.  For hashing, the
+	 * tlist should be left as-is if we don't need to add any expressions;
 	 * but if we do have to add expressions, then a projection step will be
-	 * needed at runtime anyway, and so we may as well remove unneeded items.
+	 * needed at runtime anyway, so we may as well remove unneeded items.
 	 * Therefore newtlist starts from build_relation_tlist() not just a
 	 * copy of the subplan's tlist; and we don't install it into the subplan
-	 * unless stuff has to be added.
+	 * unless we are sorting or stuff has to be added.
 	 *
 	 * To find the correct list of values to unique-ify, we look in the
 	 * information saved for IN expressions.  If this code is ever used in
@@ -669,7 +672,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path)
 		}
 	}
 
-	if (newitems)
+	if (newitems || best_path->umethod == UNIQUE_PATH_SORT)
 	{
 		/*
 		 * If the top plan node can't do projections, we need to add a Result
@@ -2850,7 +2853,7 @@ make_sort_from_groupcols(PlannerInfo *root,
 					 sortColIdx, sortOperators, nullsFirst, -1.0);
 }
 
-Material *
+static Material *
 make_material(Plan *lefttree)
 {
 	Material   *node = makeNode(Material);
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 8679e9ecf9..74e7258bba 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 1.231 2008/04/01 00:48:33 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.232 2008/04/17 21:22:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -957,9 +957,23 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 			 * Normal case --- create a plan according to query_planner's
 			 * results.
 			 */
+			bool	need_sort_for_grouping = false;
+
 			result_plan = create_plan(root, best_path);
 			current_pathkeys = best_path->pathkeys;
 
+			/* Detect if we'll need an explicit sort for grouping */
+			if (parse->groupClause && !use_hashed_grouping &&
+				!pathkeys_contained_in(group_pathkeys, current_pathkeys))
+			{
+				need_sort_for_grouping = true;
+				/*
+				 * Always override query_planner's tlist, so that we don't
+				 * sort useless data from a "physical" tlist.
+				 */
+				need_tlist_eval = true;
+			}
+
 			/*
 			 * create_plan() returns a plan with just a "flat" tlist of
 			 * required Vars.  Usually we need to insert the sub_tlist as the
@@ -1054,8 +1068,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 
 				if (parse->groupClause)
 				{
-					if (!pathkeys_contained_in(group_pathkeys,
-											   current_pathkeys))
+					if (need_sort_for_grouping)
 					{
 						result_plan = (Plan *)
 							make_sort_from_groupcols(root,
@@ -1098,7 +1111,7 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 				 * Add an explicit sort if we couldn't make the path come out
 				 * the way the GROUP node needs it.
 				 */
-				if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
+				if (need_sort_for_grouping)
 				{
 					result_plan = (Plan *)
 						make_sort_from_groupcols(root,
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index f51a399caa..74ba5131cc 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.106 2008/01/01 19:45:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.107 2008/04/17 21:22:14 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,7 +53,6 @@ extern Group *make_group(PlannerInfo *root, List *tlist, List *qual,
 		   int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
 		   double numGroups,
 		   Plan *lefttree);
-extern Material *make_material(Plan *lefttree);
 extern Plan *materialize_finished_plan(Plan *subplan);
 extern Unique *make_unique(Plan *lefttree, List *distinctList);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount,