Dept of better ideas: refrain from creating the planner's placeholder_list

until vars are distributed to rels during query_planner() startup.  We don't
really need it before that, and not building it early has some advantages.
First, we don't need to put it through the various preprocessing steps, which
saves some cycles and eliminates the need for a number of routines to support
PlaceHolderInfo nodes at all.  Second, this means one less unused plan for any
sub-SELECT appearing in a placeholder's expression, since we don't build
placeholder_list until after sublink expansion is complete.

1 files changed, 5 insertions, 10 deletions

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 05de001a877..467ff39a31b 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 1.245 2008/10/21 20:42:53 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.246 2008/10/22 20:17:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -55,7 +55,7 @@ planner_hook_type planner_hook = NULL;
 #define EXPRKIND_RTFUNC		2
 #define EXPRKIND_VALUES		3
 #define EXPRKIND_LIMIT		4
-#define EXPRKIND_AUXINFO	5
+#define EXPRKIND_APPINFO	5
 
 
 static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
@@ -274,7 +274,6 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	root->cte_plan_ids = NIL;
 	root->eq_classes = NIL;
 	root->append_rel_list = NIL;
-	root->placeholder_list = NIL;
 
 	root->hasRecursion = hasRecursion;
 	if (hasRecursion)
@@ -380,10 +379,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 
 	root->append_rel_list = (List *)
 		preprocess_expression(root, (Node *) root->append_rel_list,
-							  EXPRKIND_AUXINFO);
-	root->placeholder_list = (List *)
-		preprocess_expression(root, (Node *) root->placeholder_list,
-							  EXPRKIND_AUXINFO);
+							  EXPRKIND_APPINFO);
 
 	/* Also need to preprocess expressions for function and values RTEs */
 	foreach(l, parse->rtable)
@@ -664,11 +660,10 @@ inheritance_planner(PlannerInfo *root)
 		subroot.returningLists = NIL;
 		subroot.init_plans = NIL;
 		/* We needn't modify the child's append_rel_list */
-		subroot.placeholder_list = (List *)
-			adjust_appendrel_attrs((Node *) root->placeholder_list,
-								   appinfo);
 		/* There shouldn't be any OJ info to translate, as yet */
 		Assert(subroot.join_info_list == NIL);
+		/* and we haven't created PlaceHolderInfos, either */
+		Assert(subroot.placeholder_list == NIL);
 
 		/* Generate plan */
 		subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );