Replace "amgetmulti" AM functions with "amgetbitmap", in which the whole

indexscan always occurs in one call, and the results are returned in a
TIDBitmap instead of a limited-size array of TIDs.  This should improve
speed a little by reducing AM entry/exit overhead, and it is necessary
infrastructure if we are ever to support bitmap indexes.

In an only slightly related change, add support for TIDBitmaps to preserve
(somewhat lossily) the knowledge that particular TIDs reported by an index
need to have their quals rechecked when the heap is visited.  This facility
is not really used yet; we'll need to extend the forced-recheck feature to
plain indexscans before it's useful, and that hasn't been coded yet.
The intent is to use it to clean up 8.3's horrid @@@ kluge for text search
with weighted queries.  There might be other uses in future, but that one
alone is sufficient reason.

Heikki Linnakangas, with some adjustments by me.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h
index d40502b940d..08eaeb0aeef 100644
--- a/src/include/nodes/tidbitmap.h
+++ b/src/include/nodes/tidbitmap.h
@@ -15,7 +15,7 @@
  *
  * Copyright (c) 2003-2008, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/include/nodes/tidbitmap.h,v 1.6 2008/01/01 19:45:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/tidbitmap.h,v 1.7 2008/04/10 22:25:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,6 +36,8 @@ typedef struct
 {
 	BlockNumber blockno;		/* page number containing tuples */
 	int			ntuples;		/* -1 indicates lossy result */
+	bool		recheck;		/* should the tuples be rechecked? */
+	/* Note: recheck is always true if ntuples < 0 */
 	OffsetNumber offsets[1];	/* VARIABLE LENGTH ARRAY */
 } TBMIterateResult;				/* VARIABLE LENGTH STRUCT */
 
@@ -44,7 +46,9 @@ typedef struct
 extern TIDBitmap *tbm_create(long maxbytes);
 extern void tbm_free(TIDBitmap *tbm);
 
-extern void tbm_add_tuples(TIDBitmap *tbm, const ItemPointer tids, int ntids);
+extern void tbm_add_tuples(TIDBitmap *tbm,
+						   const ItemPointer tids, int ntids,
+						   bool recheck);
 
 extern void tbm_union(TIDBitmap *a, const TIDBitmap *b);
 extern void tbm_intersect(TIDBitmap *a, const TIDBitmap *b);