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, 20 insertions, 7 deletions

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 866cd3ef3fd..4d9dfc4c82c 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.217 2010/01/05 23:25:36 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.218 2010/02/12 17:33:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1595,23 +1595,36 @@ typedef struct WindowAggState
 	FmgrInfo   *ordEqfunctions; /* equality funcs for ordering columns */
 	Tuplestorestate *buffer;	/* stores rows of current partition */
 	int			current_ptr;	/* read pointer # for current */
-	int			agg_ptr;		/* read pointer # for aggregates */
 	int64		spooled_rows;	/* total # of rows in buffer */
 	int64		currentpos;		/* position of current row in partition */
+	int64		frameheadpos;	/* current frame head position */
 	int64		frametailpos;	/* current frame tail position */
+	/* use struct pointer to avoid including windowapi.h here */
+	struct WindowObjectData *agg_winobj;	/* winobj for aggregate fetches */
+	int64		aggregatedbase; /* start row for current aggregates */
 	int64		aggregatedupto; /* rows before this one are aggregated */
 
-	MemoryContext wincontext;	/* context for partition-lifespan data */
+	int			frameOptions;	/* frame_clause options, see WindowDef */
+	ExprState  *startOffset;	/* expression for starting bound offset */
+	ExprState  *endOffset;		/* expression for ending bound offset */
+	Datum		startOffsetValue;	/* result of startOffset evaluation */
+	Datum		endOffsetValue;		/* result of endOffset evaluation */
+
+	MemoryContext partcontext;	/* context for partition-lifespan data */
+	MemoryContext aggcontext;	/* context for each aggregate data */
 	ExprContext *tmpcontext;	/* short-term evaluation context */
 
+	bool		all_first;		/* true if the scan is starting */
 	bool		all_done;		/* true if the scan is finished */
 	bool		partition_spooled;		/* true if all tuples in current
 										 * partition have been spooled into
 										 * tuplestore */
-	bool		more_partitions;/* true if there's more partitions after this
-								 * one */
-	bool		frametail_valid;/* true if frametailpos is known up to date
-								 * for current row */
+	bool		more_partitions;	/* true if there's more partitions after
+									 * this one */
+	bool		framehead_valid;	/* true if frameheadpos is known up to date
+									 * for current row */
+	bool		frametail_valid;	/* true if frametailpos is known up to date
+									 * for current row */
 
 	TupleTableSlot *first_part_slot;	/* first tuple of current or next
 										 * partition */