Move the handling of SELECT FOR UPDATE locking and rechecking out of

execMain.c and into a new plan node type LockRows.  Like the recent change
to put table updating into a ModifyTable plan node, this increases planning
flexibility by allowing the operations to occur below the top level of the
plan tree.  It's necessary in any case to restore the previous behavior of
having FOR UPDATE locking occur before ModifyTable does.

This partially refactors EvalPlanQual to allow multiple rows-under-test
to be inserted into the EPQ machinery before starting an EPQ test query.
That isn't sufficient to fix EPQ's general bogosity in the face of plans
that return multiple rows per test row, though.  Since this patch is
mostly about getting some plan node infrastructure in place and not about
fixing ten-year-old bugs, I will leave EPQ improvements for another day.

Another behavioral change that we could now think about is doing FOR UPDATE
before LIMIT, but that too seems like it should be treated as a followon
patch.

1 files changed, 13 insertions, 4 deletions

diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 6a813106d1..7b0dd75e7f 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.154 2009/10/10 01:43:49 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.155 2009/10/12 18:10:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,7 +53,8 @@ typedef struct finalize_primnode_context
 } finalize_primnode_context;
 
 
-static Node *build_subplan(PlannerInfo *root, Plan *plan, List *rtable,
+static Node *build_subplan(PlannerInfo *root, Plan *plan,
+			  List *rtable, List *rowmarks,
 			  SubLinkType subLinkType, Node *testexpr,
 			  bool adjust_testexpr, bool unknownEqFalse);
 static List *generate_subquery_params(PlannerInfo *root, List *tlist,
@@ -333,7 +334,8 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
 							&subroot);
 
 	/* And convert to SubPlan or InitPlan format. */
-	result = build_subplan(root, plan, subroot->parse->rtable,
+	result = build_subplan(root, plan,
+						   subroot->parse->rtable, subroot->parse->rowMarks,
 						   subLinkType, testexpr, true, isTopQual);
 
 	/*
@@ -375,6 +377,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
 				/* OK, convert to SubPlan format. */
 				hashplan = (SubPlan *) build_subplan(root, plan,
 													 subroot->parse->rtable,
+													 subroot->parse->rowMarks,
 													 ANY_SUBLINK, newtestexpr,
 													 false, true);
 				/* Check we got what we expected */
@@ -402,7 +405,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery, SubLinkType subLinkType,
  * as explained in the comments for make_subplan.
  */
 static Node *
-build_subplan(PlannerInfo *root, Plan *plan, List *rtable,
+build_subplan(PlannerInfo *root, Plan *plan, List *rtable, List *rowmarks,
 			  SubLinkType subLinkType, Node *testexpr,
 			  bool adjust_testexpr, bool unknownEqFalse)
 {
@@ -585,6 +588,7 @@ build_subplan(PlannerInfo *root, Plan *plan, List *rtable,
 	 */
 	root->glob->subplans = lappend(root->glob->subplans, plan);
 	root->glob->subrtables = lappend(root->glob->subrtables, rtable);
+	root->glob->subrowmarks = lappend(root->glob->subrowmarks, rowmarks);
 	splan->plan_id = list_length(root->glob->subplans);
 
 	if (isInitPlan)
@@ -944,6 +948,8 @@ SS_process_ctes(PlannerInfo *root)
 		root->glob->subplans = lappend(root->glob->subplans, plan);
 		root->glob->subrtables = lappend(root->glob->subrtables,
 										 subroot->parse->rtable);
+		root->glob->subrowmarks = lappend(root->glob->subrowmarks,
+										  subroot->parse->rowMarks);
 		splan->plan_id = list_length(root->glob->subplans);
 
 		root->init_plans = lappend(root->init_plans, splan);
@@ -2035,6 +2041,7 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params)
 		case T_Unique:
 		case T_SetOp:
 		case T_Group:
+		case T_LockRows:
 			break;
 
 		default:
@@ -2191,6 +2198,8 @@ SS_make_initplan_from_plan(PlannerInfo *root, Plan *plan,
 								   plan);
 	root->glob->subrtables = lappend(root->glob->subrtables,
 									 root->parse->rtable);
+	root->glob->subrowmarks = lappend(root->glob->subrowmarks,
+									  root->parse->rowMarks);
 
 	/*
 	 * Create a SubPlan node and add it to the outer list of InitPlans. Note