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

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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.
This commit is contained in:
Tom Lane
2008-12-31 00:08:39 +00:00
parent 0fb9be7acf
commit 8e8854daa2
24 changed files with 757 additions and 307 deletions
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38
src/include/nodes/parsenodes.h
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@@ -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 $
*
*-------------------------------------------------------------------------
*/
@@ -382,17 +382,46 @@ 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
*/
@@ -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;