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 b7c0c2a..e886b88 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 */