Support all SQL:2011 options for window frame clauses.

This patch adds the ability to use "RANGE offset PRECEDING/FOLLOWING"
frame boundaries in window functions.  We'd punted on that back in the
original patch to add window functions, because it was not clear how to
do it in a reasonably data-type-extensible fashion.  That problem is
resolved here by adding the ability for btree operator classes to provide
an "in_range" support function that defines how to add or subtract the
RANGE offset value.  Factoring it this way also allows the operator class
to avoid overflow problems near the ends of the datatype's range, if it
wishes to expend effort on that.  (In the committed patch, the integer
opclasses handle that issue, but it did not seem worth the trouble to
avoid overflow failures for datetime types.)

The patch includes in_range support for the integer_ops opfamily
(int2/int4/int8) as well as the standard datetime types.  Support for
other numeric types has been requested, but that seems like suitable
material for a follow-on patch.

In addition, the patch adds GROUPS mode which counts the offset in
ORDER-BY peer groups rather than rows, and it adds the frame_exclusion
options specified by SQL:2011.  As far as I can see, we are now fully
up to spec on window framing options.

Existing behaviors remain unchanged, except that I changed the errcode
for a couple of existing error reports to meet the SQL spec's expectation
that negative "offset" values should be reported as SQLSTATE 22013.

Internally and in relevant parts of the documentation, we now consistently
use the terminology "offset PRECEDING/FOLLOWING" rather than "value
PRECEDING/FOLLOWING", since the term "value" is confusingly vague.

Oliver Ford, reviewed and whacked around some by me

Discussion: https://postgr.es/m/CAGMVOdu9sivPAxbNN0X+q19Sfv9edEPv=HibOJhB14TJv_RCQg@mail.gmail.com

1 files changed, 31 insertions, 17 deletions

diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index a16de289ba8..c7a43b8933f 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -499,27 +499,33 @@ typedef struct WindowDef
  * 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_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_GROUPS						0x00008 /* GROUPS behavior */
+#define FRAMEOPTION_BETWEEN						0x00010 /* BETWEEN given? */
+#define FRAMEOPTION_START_UNBOUNDED_PRECEDING	0x00020 /* start is U. P. */
+#define FRAMEOPTION_END_UNBOUNDED_PRECEDING		0x00040 /* (disallowed) */
+#define FRAMEOPTION_START_UNBOUNDED_FOLLOWING	0x00080 /* (disallowed) */
+#define FRAMEOPTION_END_UNBOUNDED_FOLLOWING		0x00100 /* end is U. F. */
+#define FRAMEOPTION_START_CURRENT_ROW			0x00200 /* start is C. R. */
+#define FRAMEOPTION_END_CURRENT_ROW				0x00400 /* end is C. R. */
+#define FRAMEOPTION_START_OFFSET_PRECEDING		0x00800 /* start is O. P. */
+#define FRAMEOPTION_END_OFFSET_PRECEDING		0x01000 /* end is O. P. */
+#define FRAMEOPTION_START_OFFSET_FOLLOWING		0x02000 /* start is O. F. */
+#define FRAMEOPTION_END_OFFSET_FOLLOWING		0x04000 /* end is O. F. */
+#define FRAMEOPTION_EXCLUDE_CURRENT_ROW			0x08000 /* omit C.R. */
+#define FRAMEOPTION_EXCLUDE_GROUP				0x10000 /* omit C.R. & peers */
+#define FRAMEOPTION_EXCLUDE_TIES				0x20000 /* omit C.R.'s peers */
+
+#define FRAMEOPTION_START_OFFSET \
+	(FRAMEOPTION_START_OFFSET_PRECEDING | FRAMEOPTION_START_OFFSET_FOLLOWING)
+#define FRAMEOPTION_END_OFFSET \
+	(FRAMEOPTION_END_OFFSET_PRECEDING | FRAMEOPTION_END_OFFSET_FOLLOWING)
+#define FRAMEOPTION_EXCLUSION \
+	(FRAMEOPTION_EXCLUDE_CURRENT_ROW | FRAMEOPTION_EXCLUDE_GROUP | \
+	 FRAMEOPTION_EXCLUDE_TIES)
 
 #define FRAMEOPTION_DEFAULTS \
 	(FRAMEOPTION_RANGE | FRAMEOPTION_START_UNBOUNDED_PRECEDING | \
@@ -1277,6 +1283,9 @@ typedef struct GroupingSet
  * if the clause originally came from WINDOW, and is NULL if it originally
  * was an OVER clause (but note that we collapse out duplicate OVERs).
  * partitionClause and orderClause are lists of SortGroupClause structs.
+ * If we have RANGE with offset PRECEDING/FOLLOWING, the semantics of that are
+ * specified by startInRangeFunc/inRangeColl/inRangeAsc/inRangeNullsFirst
+ * for the start offset, or endInRangeFunc/inRange* for the end offset.
  * 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;
@@ -1293,6 +1302,11 @@ typedef struct WindowClause
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
+	Oid			startInRangeFunc;	/* in_range function for startOffset */
+	Oid			endInRangeFunc; /* in_range function for endOffset */
+	Oid			inRangeColl;	/* collation for in_range tests */
+	bool		inRangeAsc;		/* use ASC sort order for in_range tests? */
+	bool		inRangeNullsFirst;	/* nulls sort first for in_range tests? */
 	Index		winref;			/* ID referenced by window functions */
 	bool		copiedOrder;	/* did we copy orderClause from refname? */
 } WindowClause;