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.

6 files changed, 14 insertions, 16 deletions

diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index df3c7f0ed95..57785913394 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.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/access/genam.h,v 1.69 2008/01/01 19:45:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/genam.h,v 1.70 2008/04/10 22:25:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,6 +17,7 @@
 #include "access/relscan.h"
 #include "access/sdir.h"
 #include "nodes/primnodes.h"
+#include "nodes/tidbitmap.h"
 #include "storage/lock.h"
 
 /*
@@ -99,7 +100,7 @@ extern IndexScanDesc index_beginscan(Relation heapRelation,
 				Relation indexRelation,
 				Snapshot snapshot,
 				int nkeys, ScanKey key);
-extern IndexScanDesc index_beginscan_multi(Relation indexRelation,
+extern IndexScanDesc index_beginscan_bitmap(Relation indexRelation,
 					  Snapshot snapshot,
 					  int nkeys, ScanKey key);
 extern void index_rescan(IndexScanDesc scan, ScanKey key);
@@ -109,9 +110,7 @@ extern void index_restrpos(IndexScanDesc scan);
 extern HeapTuple index_getnext(IndexScanDesc scan, ScanDirection direction);
 extern bool index_getnext_indexitem(IndexScanDesc scan,
 						ScanDirection direction);
-extern bool index_getmulti(IndexScanDesc scan,
-			   ItemPointer tids, int32 max_tids,
-			   int32 *returned_tids);
+extern int64 index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap);
 
 extern IndexBulkDeleteResult *index_bulk_delete(IndexVacuumInfo *info,
 				  IndexBulkDeleteResult *stats,
diff --git a/src/include/access/gin.h b/src/include/access/gin.h
index d27ba66a597..7a343c62c49 100644
--- a/src/include/access/gin.h
+++ b/src/include/access/gin.h
@@ -4,7 +4,7 @@
  *
  *	Copyright (c) 2006-2008, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/include/access/gin.h,v 1.16 2008/01/01 19:45:56 momjian Exp $
+ *	$PostgreSQL: pgsql/src/include/access/gin.h,v 1.17 2008/04/10 22:25:25 tgl Exp $
  *--------------------------------------------------------------------------
  */
 
@@ -422,7 +422,7 @@ extern PGDLLIMPORT int GinFuzzySearchLimit;
 #define ItemPointerSetMin(p)	ItemPointerSet( (p), (BlockNumber)0, (OffsetNumber)0)
 #define ItemPointerIsMin(p) ( ItemPointerGetBlockNumber(p) == (BlockNumber)0 && ItemPointerGetOffsetNumber(p) == (OffsetNumber)0 )
 
-extern Datum gingetmulti(PG_FUNCTION_ARGS);
+extern Datum gingetbitmap(PG_FUNCTION_ARGS);
 extern Datum gingettuple(PG_FUNCTION_ARGS);
 
 /* ginvacuum.c */
diff --git a/src/include/access/gist_private.h b/src/include/access/gist_private.h
index e6ca50a702f..b34388b4ed1 100644
--- a/src/include/access/gist_private.h
+++ b/src/include/access/gist_private.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/access/gist_private.h,v 1.28 2008/01/01 19:45:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.29 2008/04/10 22:25:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -269,7 +269,7 @@ extern XLogRecPtr gistxlogInsertCompletion(RelFileNode node, ItemPointerData *ke
 
 /* gistget.c */
 extern Datum gistgettuple(PG_FUNCTION_ARGS);
-extern Datum gistgetmulti(PG_FUNCTION_ARGS);
+extern Datum gistgetbitmap(PG_FUNCTION_ARGS);
 
 /* gistutil.c */
 
diff --git a/src/include/access/hash.h b/src/include/access/hash.h
index 34275ad9d60..a786117ee55 100644
--- a/src/include/access/hash.h
+++ b/src/include/access/hash.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/access/hash.h,v 1.86 2008/03/16 23:15:08 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/hash.h,v 1.87 2008/04/10 22:25:25 tgl Exp $
  *
  * NOTES
  *		modeled after Margo Seltzer's hash implementation for unix.
@@ -233,7 +233,7 @@ extern Datum hashbuild(PG_FUNCTION_ARGS);
 extern Datum hashinsert(PG_FUNCTION_ARGS);
 extern Datum hashbeginscan(PG_FUNCTION_ARGS);
 extern Datum hashgettuple(PG_FUNCTION_ARGS);
-extern Datum hashgetmulti(PG_FUNCTION_ARGS);
+extern Datum hashgetbitmap(PG_FUNCTION_ARGS);
 extern Datum hashrescan(PG_FUNCTION_ARGS);
 extern Datum hashendscan(PG_FUNCTION_ARGS);
 extern Datum hashmarkpos(PG_FUNCTION_ARGS);
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 2bcf8ab38f4..1422994506d 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.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/access/nbtree.h,v 1.116 2008/01/01 19:45:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.117 2008/04/10 22:25:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -507,7 +507,7 @@ extern Datum btbuild(PG_FUNCTION_ARGS);
 extern Datum btinsert(PG_FUNCTION_ARGS);
 extern Datum btbeginscan(PG_FUNCTION_ARGS);
 extern Datum btgettuple(PG_FUNCTION_ARGS);
-extern Datum btgetmulti(PG_FUNCTION_ARGS);
+extern Datum btgetbitmap(PG_FUNCTION_ARGS);
 extern Datum btrescan(PG_FUNCTION_ARGS);
 extern Datum btendscan(PG_FUNCTION_ARGS);
 extern Datum btmarkpos(PG_FUNCTION_ARGS);
diff --git a/src/include/access/relscan.h b/src/include/access/relscan.h
index eebcc86bb30..677fd04e2c2 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.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/access/relscan.h,v 1.61 2008/03/26 16:20:48 alvherre Exp $
+ * $PostgreSQL: pgsql/src/include/access/relscan.h,v 1.62 2008/04/10 22:25:25 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -57,7 +57,7 @@ typedef HeapScanDescData *HeapScanDesc;
 
 /*
  * We use the same IndexScanDescData structure for both amgettuple-based
- * and amgetmulti-based index scans.  Some fields are only relevant in
+ * and amgetbitmap-based index scans.  Some fields are only relevant in
  * amgettuple-based scans.
  */
 typedef struct IndexScanDescData
@@ -68,7 +68,6 @@ typedef struct IndexScanDescData
 	Snapshot	xs_snapshot;	/* snapshot to see */
 	int			numberOfKeys;	/* number of scan keys */
 	ScanKey		keyData;		/* array of scan key descriptors */
-	bool		is_multiscan;	/* TRUE = using amgetmulti */
 
 	/* signaling to index AM about killing index tuples */
 	bool		kill_prior_tuple;		/* last-returned tuple is dead */