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

1 files changed, 18 insertions, 2 deletions

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 3748c83fd65..77e9d65ae7e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/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);
 			}
 		}