Extend the set of frame options supported for window functions.

This patch allows the frame to start from CURRENT ROW (in either RANGE or
ROWS mode), and it also adds support for ROWS n PRECEDING and ROWS n FOLLOWING
start and end points.  (RANGE value PRECEDING/FOLLOWING isn't there yet ---
the grammar works, but that's all.)

Hitoshi Harada, reviewed by Pavel Stehule

src/backend/optimizer/plan/createplan.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.270 2010/01/02 16:57:47 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.271 2010/02/12 17:33:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3364,7 +3364,8 @@ make_windowagg(PlannerInfo *root, List *tlist,
 			   int numWindowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
 			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
-			   int frameOptions, Plan *lefttree)
+			   int frameOptions, Node *startOffset, Node *endOffset,
+			   Plan *lefttree)
 {
 	WindowAgg  *node = makeNode(WindowAgg);
 	Plan	   *plan = &node->plan;
@@ -3379,6 +3380,8 @@ make_windowagg(PlannerInfo *root, List *tlist,
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
 	node->frameOptions = frameOptions;
+	node->startOffset = startOffset;
+	node->endOffset = endOffset;
 
 	copy_plan_costsize(plan, lefttree); /* only care about copying size */
 	cost_windowagg(&windowagg_path, root,

src/backend/optimizer/plan/planner.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.264 2010/02/10 03:38:35 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.265 2010/02/12 17:33:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -398,7 +398,10 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	root->hasPseudoConstantQuals = false;
 
 	/*
-	 * Do expression preprocessing on targetlist and quals.
+	 * Do expression preprocessing on targetlist and quals, as well as other
+	 * random expressions in the querytree.  Note that we do not need to
+	 * handle sort/group expressions explicitly, because they are actually
+	 * part of the targetlist.
 	 */
 	parse->targetList = (List *)
 		preprocess_expression(root, (Node *) parse->targetList,
@@ -413,6 +416,17 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 	parse->havingQual = preprocess_expression(root, parse->havingQual,
 											  EXPRKIND_QUAL);
 
+	foreach(l, parse->windowClause)
+	{
+		WindowClause *wc = (WindowClause *) lfirst(l);
+
+		/* partitionClause/orderClause are sort/group expressions */
+		wc->startOffset = preprocess_expression(root, wc->startOffset,
+												EXPRKIND_LIMIT);
+		wc->endOffset = preprocess_expression(root, wc->endOffset,
+											  EXPRKIND_LIMIT);
+	}
+
 	parse->limitOffset = preprocess_expression(root, parse->limitOffset,
 											   EXPRKIND_LIMIT);
 	parse->limitCount = preprocess_expression(root, parse->limitCount,
@@ -1513,6 +1527,8 @@ grouping_planner(PlannerInfo *root, double tuple_fraction)
 								   ordColIdx,
 								   ordOperators,
 								   wc->frameOptions,
+								   wc->startOffset,
+								   wc->endOffset,
 								   result_plan);
 			}
 		}

src/backend/optimizer/plan/setrefs.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.157 2010/01/15 22:36:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.158 2010/02/12 17:33:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -466,10 +466,26 @@ set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset)
 			}
 			break;
 		case T_Agg:
-		case T_WindowAgg:
 		case T_Group:
 			set_upper_references(glob, plan, rtoffset);
 			break;
+		case T_WindowAgg:
+			{
+				WindowAgg	   *wplan = (WindowAgg *) plan;
+
+				set_upper_references(glob, plan, rtoffset);
+
+				/*
+				 * Like Limit node limit/offset expressions, WindowAgg has
+				 * frame offset expressions, which cannot contain subplan
+				 * variable refs, so fix_scan_expr works for them.
+				 */
+				wplan->startOffset =
+					fix_scan_expr(glob, wplan->startOffset, rtoffset);
+				wplan->endOffset =
+					fix_scan_expr(glob, wplan->endOffset, rtoffset);
+			}
+			break;
 		case T_Result:
 			{
 				Result	   *splan = (Result *) plan;

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 1.158 2010/01/18 18:17:45 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.159 2010/02/12 17:33:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2098,9 +2098,15 @@ finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params,
 										 locally_added_param);
 			break;
 
+		case T_WindowAgg:
+			finalize_primnode(((WindowAgg *) plan)->startOffset,
+							  &context);
+			finalize_primnode(((WindowAgg *) plan)->endOffset,
+							  &context);
+			break;
+
 		case T_Hash:
 		case T_Agg:
-		case T_WindowAgg:
 		case T_Material:
 		case T_Sort:
 		case T_Unique: