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, 14 insertions, 1 deletions

diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index ffa6055a57a..0c3aecfa6e6 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.428 2010/02/08 04:33:54 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.429 2010/02/12 17:33:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -393,6 +393,8 @@ typedef struct WindowDef
 	List	   *partitionClause;	/* PARTITION BY expression list */
 	List	   *orderClause;	/* ORDER BY (list of SortBy) */
 	int			frameOptions;	/* frame_clause options, see below */
+	Node	   *startOffset;	/* expression for starting bound, if any */
+	Node	   *endOffset;		/* expression for ending bound, if any */
 	int			location;		/* parse location, or -1 if none/unknown */
 } WindowDef;
 
@@ -414,6 +416,15 @@ typedef struct WindowDef
 #define FRAMEOPTION_END_UNBOUNDED_FOLLOWING		0x00080 /* end is U. F. */
 #define FRAMEOPTION_START_CURRENT_ROW			0x00100 /* start is C. R. */
 #define FRAMEOPTION_END_CURRENT_ROW				0x00200 /* end is C. R. */
+#define FRAMEOPTION_START_VALUE_PRECEDING		0x00400 /* start is V. P. */
+#define FRAMEOPTION_END_VALUE_PRECEDING			0x00800 /* end is V. P. */
+#define FRAMEOPTION_START_VALUE_FOLLOWING		0x01000 /* start is V. F. */
+#define FRAMEOPTION_END_VALUE_FOLLOWING			0x02000 /* end is V. F. */
+
+#define FRAMEOPTION_START_VALUE \
+	(FRAMEOPTION_START_VALUE_PRECEDING | FRAMEOPTION_START_VALUE_FOLLOWING)
+#define FRAMEOPTION_END_VALUE \
+	(FRAMEOPTION_END_VALUE_PRECEDING | FRAMEOPTION_END_VALUE_FOLLOWING)
 
 #define FRAMEOPTION_DEFAULTS \
 	(FRAMEOPTION_RANGE | FRAMEOPTION_START_UNBOUNDED_PRECEDING | \
@@ -799,6 +810,8 @@ typedef struct WindowClause
 	List	   *partitionClause;	/* PARTITION BY list */
 	List	   *orderClause;	/* ORDER BY list */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
+	Node	   *startOffset;	/* expression for starting bound, if any */
+	Node	   *endOffset;		/* expression for ending bound, if any */
 	Index		winref;			/* ID referenced by window functions */
 	bool		copiedOrder;	/* did we copy orderClause from refname? */
 } WindowClause;