Cause planner to include costs of InitPlans in startup cost of parent

plan node.  Not sure why this oversight has persisted so long ...

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index b7c0c2ad4b5a590db6b5bbb94d323ca63605d303..e886b88184e19fbd26375307c85992a91a6e6aee 100644 (file)
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.135 2002/12/14 00:17:55 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.136 2002/12/19 23:25:01 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -264,25 +264,38 @@ subquery_planner(Query *parse, double tuple_fraction)
 
    /*
     * If any subplans were generated, or if we're inside a subplan, build
-    * subPlan, extParam and locParam lists for plan nodes.
+    * initPlan, extParam and locParam lists for plan nodes.
     */
    if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1)
    {
+       Cost    initplan_cost = 0;
+
+       /* Prepare extParam/locParam data for all nodes in tree */
        (void) SS_finalize_plan(plan, parse->rtable);
 
        /*
-        * At the moment, SS_finalize_plan doesn't handle initPlans and so
-        * we assign them to the topmost plan node.
+        * SS_finalize_plan doesn't handle initPlans, so we have to manually
+        * attach them to the topmost plan node, and add their extParams to
+        * the topmost node's, too.
+        *
+        * We also add the total_cost of each initPlan to the startup cost
+        * of the top node.  This is a conservative overestimate, since in
+        * fact each initPlan might be executed later than plan startup, or
+        * even not at all.
         */
        plan->initPlan = PlannerInitPlan;
-       /* Must add the initPlans' extParams to the topmost node's, too */
+
        foreach(lst, plan->initPlan)
        {
-           SubPlan    *subplan = (SubPlan *) lfirst(lst);
+           SubPlan    *initplan = (SubPlan *) lfirst(lst);
 
            plan->extParam = set_unioni(plan->extParam,
-                                       subplan->plan->extParam);
+                                       initplan->plan->extParam);
+           initplan_cost += initplan->plan->total_cost;
        }
+
+       plan->startup_cost += initplan_cost;
+       plan->total_cost += initplan_cost;
    }
 
    /* Return to outer subquery context */