Add some basic support for window frame clauses to the window-functions

patch.  This includes the ability to force the frame to cover the whole
partition, and the ability to make the frame end exactly on the current row
rather than its last ORDER BY peer.  Supporting any more of the full SQL
frame-clause syntax will require nontrivial hacking on the window aggregate
code, so it'll have to wait for 8.5 or beyond.

5 files changed, 46 insertions, 12 deletions

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 21bbd429ae..eff2c3bf9a 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.514 2008/12/28 18:53:59 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.515 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200812281
+#define CATALOG_VERSION_NO	200812301
 
 #endif
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 258abdee6a..8d3746f2cf 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.197 2008/12/28 18:54:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.198 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1533,12 +1533,14 @@ typedef struct WindowAggState
 									 * 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 */
 
 	TupleTableSlot *first_part_slot;	/* first tuple of current or next
 										 * partition */
 
 	/* temporary slots for tuples fetched back from tuplestore */
-	TupleTableSlot *first_peer_slot;
+	TupleTableSlot *agg_row_slot;
 	TupleTableSlot *temp_slot_1;
 	TupleTableSlot *temp_slot_2;
 } WindowAggState;
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 43c4452d78..6a0cca3632 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.385 2008/12/28 18:54:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.386 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -382,18 +382,47 @@ typedef struct SortBy
 
 /*
  * WindowDef - raw representation of WINDOW and OVER clauses
+ *
+ * For entries in a WINDOW list, "name" is the window name being defined.
+ * For OVER clauses, we use "name" for the "OVER window" syntax, or "refname"
+ * for the "OVER (window)" syntax, which is subtly different --- the latter
+ * implies overriding the window frame clause.
  */
 typedef struct WindowDef
 {
 	NodeTag		type;
-	char	   *name;				/* window name (NULL in an OVER clause) */
+	char	   *name;				/* window's own name */
 	char	   *refname;			/* referenced window name, if any */
 	List	   *partitionClause;	/* PARTITION BY expression list */
 	List	   *orderClause;		/* ORDER BY (list of SortBy) */
+	int			frameOptions;		/* frame_clause options, see below */
 	int			location;			/* parse location, or -1 if none/unknown */
 } WindowDef;
 
 /*
+ * frameOptions is an OR of these bits.  The NONDEFAULT and BETWEEN bits are
+ * used so that ruleutils.c can tell which properties were specified and
+ * which were defaulted; the correct behavioral bits must be set either way.
+ * The START_foo and END_foo options must come in pairs of adjacent bits for
+ * the convenience of gram.y, even though some of them are useless/invalid.
+ * We will need more bits (and fields) to cover the full SQL:2008 option set.
+ */
+#define FRAMEOPTION_NONDEFAULT					0x00001	/* any specified? */
+#define FRAMEOPTION_RANGE						0x00002	/* RANGE behavior */
+#define FRAMEOPTION_ROWS						0x00004	/* ROWS behavior */
+#define FRAMEOPTION_BETWEEN						0x00008	/* BETWEEN given? */
+#define FRAMEOPTION_START_UNBOUNDED_PRECEDING	0x00010	/* start is U. P. */
+#define FRAMEOPTION_END_UNBOUNDED_PRECEDING		0x00020	/* (disallowed) */
+#define FRAMEOPTION_START_UNBOUNDED_FOLLOWING	0x00040	/* (disallowed) */
+#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_DEFAULTS \
+	(FRAMEOPTION_RANGE | FRAMEOPTION_START_UNBOUNDED_PRECEDING | \
+	 FRAMEOPTION_END_CURRENT_ROW)
+
+/*
  * RangeSubselect - subquery appearing in a FROM clause
  */
 typedef struct RangeSubselect
@@ -744,8 +773,8 @@ typedef struct SortGroupClause
  * winref is an ID number referenced by WindowFunc nodes; it must be unique
  * among the members of a Query's windowClause list.
  * When refname isn't null, the partitionClause is always copied from there;
- * the orderClause might or might not be copied.  (We don't implement
- * framing clauses yet, but if we did, they are never copied, per spec.)
+ * the orderClause might or might not be copied (see copiedOrder); the framing
+ * options are never copied, per spec.
  */
 typedef struct WindowClause
 {
@@ -754,6 +783,7 @@ typedef struct WindowClause
 	char	   *refname;			/* referenced window name, if any */
 	List	   *partitionClause;	/* PARTITION BY list */
 	List	   *orderClause;		/* ORDER BY list */
+	int			frameOptions;		/* frame_clause options, see WindowDef */
 	Index		winref;				/* ID referenced by window functions */
 	bool		copiedOrder;		/* did we copy orderClause from refname? */
 } WindowClause;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index e320fd5fb4..959a4a9f7c 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.106 2008/12/28 18:54:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/plannodes.h,v 1.107 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -543,12 +543,14 @@ typedef struct Agg
 typedef struct WindowAgg
 {
 	Plan		plan;
+	Index		winref;			/* ID referenced by window functions */
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	int			frameOptions;	/* frame_clause options, see WindowDef */
 } WindowAgg;
 
 /* ----------------
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index d6f5ff160f..5ae7162521 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.115 2008/12/28 18:54:01 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.116 2008/12/31 00:08:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,10 +57,10 @@ extern Agg *make_agg(PlannerInfo *root, List *tlist, List *qual,
 		 long numGroups, int numAggs,
 		 Plan *lefttree);
 extern WindowAgg *make_windowagg(PlannerInfo *root, List *tlist,
-			   int numWindowFuncs,
+			   int numWindowFuncs, Index winref,
 			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
 			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
-			   Plan *lefttree);
+			   int frameOptions, Plan *lefttree);
 extern Group *make_group(PlannerInfo *root, List *tlist, List *qual,
 		   int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
 		   double numGroups,