Restructure parsetree representation of DECLARE CURSOR: now it's a

utility statement (DeclareCursorStmt) with a SELECT query dangling from
it, rather than a SELECT query with a few unusual fields in it.  Add
code to determine whether a planned query can safely be run backwards.
If DECLARE CURSOR specifies SCROLL, ensure that the plan can be run
backwards by adding a Materialize plan node if it can't.  Without SCROLL,
you get an error if you try to fetch backwards from a cursor that can't
handle it.  (There is still some discussion about what the exact
behavior should be, but this is necessary infrastructure in any case.)
Along the way, make EXPLAIN DECLARE CURSOR work.

1 files changed, 36 insertions, 1 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index bfc11aa0046..d01acdc6182 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.137 2003/02/16 06:06:32 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.138 2003/03/10 03:53:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1827,6 +1827,41 @@ make_material(List *tlist, Plan *lefttree)
 	return node;
 }
 
+/*
+ * materialize_finished_plan: stick a Material node atop a completed plan
+ *
+ * There are a couple of places where we want to attach a Material node
+ * after completion of subquery_planner().  This currently requires hackery.
+ * Since subquery_planner has already run SS_finalize_plan on the subplan
+ * tree, we have to kluge up parameter lists for the Material node.
+ * Possibly this could be fixed by postponing SS_finalize_plan processing
+ * until setrefs.c is run?
+ */
+Plan *
+materialize_finished_plan(Plan *subplan)
+{
+	Plan	   *matplan;
+	Path		matpath;		/* dummy for result of cost_material */
+
+	matplan = (Plan *) make_material(subplan->targetlist, subplan);
+
+	/* Set cost data */
+	cost_material(&matpath,
+				  subplan->total_cost,
+				  subplan->plan_rows,
+				  subplan->plan_width);
+	matplan->startup_cost = matpath.startup_cost;
+	matplan->total_cost = matpath.total_cost;
+	matplan->plan_rows = subplan->plan_rows;
+	matplan->plan_width = subplan->plan_width;
+
+	/* parameter kluge --- see comments above */
+	matplan->extParam = bms_copy(subplan->extParam);
+	matplan->allParam = bms_copy(subplan->allParam);
+
+	return matplan;
+}
+
 Agg *
 make_agg(Query *root, List *tlist, List *qual,
 		 AggStrategy aggstrategy,