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.

30 files changed, 396 insertions, 245 deletions

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index c0a018a509..5fbb2c6185 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -473,10 +473,10 @@
      </row>
 
      <row>
-      <entry><structfield>amgetmulti</structfield></entry>
+      <entry><structfield>amgetbitmap</structfield></entry>
       <entry><type>regproc</type></entry>
       <entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
-      <entry><quote>Fetch multiple tuples</quote> function</entry>
+      <entry><quote>Fetch all valid tuples</quote> function</entry>
      </row>
 
      <row>
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml
index 0e52c0eb91..772ed119be 100644
--- a/doc/src/sgml/indexam.sgml
+++ b/doc/src/sgml/indexam.sgml
@@ -320,23 +320,16 @@ amgettuple (IndexScanDesc scan,
 
   <para>
 <programlisting>
-boolean
-amgetmulti (IndexScanDesc scan,
-            ItemPointer tids,
-            int32 max_tids,
-            int32 *returned_tids);
+int64
+amgetbitmap (IndexScanDesc scan,
+             TIDBitmap *tbm);
 </programlisting>
-   Fetch multiple tuples in the given scan.  Returns TRUE if the scan should
-   continue, FALSE if no matching tuples remain.  <literal>tids</> points to
-   a caller-supplied array of <literal>max_tids</>
-   <structname>ItemPointerData</> records, which the call fills with TIDs of
-   matching tuples.  <literal>*returned_tids</> is set to the number of TIDs
-   actually returned.  This can be less than <literal>max_tids</>, or even
-   zero, even when the return value is TRUE.  (This provision allows the
-   access method to choose the most efficient stopping points in its scan,
-   for example index page boundaries.)  <function>amgetmulti</> and
+   Fetch all tuples in the given scan and add them to the caller-supplied
+   TIDBitmap (that is, OR the set of tuple IDs into whatever set is already
+   in the bitmap).  The number of tuples fetched is returned. 
+   <function>amgetbitmap</> and
    <function>amgettuple</> cannot be used in the same index scan; there
-   are other restrictions too when using <function>amgetmulti</>, as explained
+   are other restrictions too when using <function>amgetbitmap</>, as explained
    in <xref linkend="index-scanning">.
   </para>
 
@@ -491,20 +484,17 @@ amrestrpos (IndexScanDesc scan);
 
   <para>
    Instead of using <function>amgettuple</>, an index scan can be done with 
-   <function>amgetmulti</> to fetch multiple tuples per call.  This can be
+   <function>amgetbitmap</> to fetch all tuples in one call.  This can be
    noticeably more efficient than <function>amgettuple</> because it allows
    avoiding lock/unlock cycles within the access method.  In principle
-   <function>amgetmulti</> should have the same effects as repeated
+   <function>amgetbitmap</> should have the same effects as repeated
    <function>amgettuple</> calls, but we impose several restrictions to
-   simplify matters.  In the first place, <function>amgetmulti</> does not
-   take a <literal>direction</> argument, and therefore it does not support
-   backwards scan nor intrascan reversal of direction.  The access method
-   need not support marking or restoring scan positions during an
-   <function>amgetmulti</> scan, either.  (These restrictions cost little
-   since it would be difficult to use these features in an
-   <function>amgetmulti</> scan anyway: adjusting the caller's buffered
-   list of TIDs would be complex.)  Finally, <function>amgetmulti</> does
-   not guarantee any locking of the returned tuples, with implications
+   simplify matters.  First of all, <function>amgetbitmap</> returns all 
+   tuples at once and marking or restoring scan positions isn't 
+   supported. Secondly, the tuples are returned in a bitmap which doesn't
+   have any specific ordering, which is why <function>amgetbitmap</> doesn't
+   take a <literal>direction</> argument.  Finally, <function>amgetbitmap</>
+   does not guarantee any locking of the returned tuples, with implications
    spelled out in <xref linkend="index-locking">.
   </para>
 
@@ -605,9 +595,8 @@ amrestrpos (IndexScanDesc scan);
   </para>
 
   <para>
-   In an <function>amgetmulti</> index scan, the access method need not
-   guarantee to keep an index pin on any of the returned tuples.  (It would be
-   impractical to pin more than the last one anyway.)  Therefore
+   In an <function>amgetbitmap</> index scan, the access method does not
+   keep an index pin on any of the returned tuples.  Therefore
    it is only safe to use such scans with MVCC-compliant snapshots.
   </para>
 
diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c
index d292704350..e2025f73b4 100644
--- a/src/backend/access/gin/ginget.c
+++ b/src/backend/access/gin/ginget.c
@@ -13,8 +13,10 @@
  */
 
 #include "postgres.h"
+
 #include "access/gin.h"
 #include "catalog/index.h"
+#include "miscadmin.h"
 #include "utils/memutils.h"
 
 static bool
@@ -476,34 +478,37 @@ scanGetItem(IndexScanDesc scan, ItemPointerData *item)
 #define GinIsVoidRes(s)		( ((GinScanOpaque) scan->opaque)->isVoidRes == true )
 
 Datum
-gingetmulti(PG_FUNCTION_ARGS)
+gingetbitmap(PG_FUNCTION_ARGS)
 {
 	IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
-	ItemPointer tids = (ItemPointer) PG_GETARG_POINTER(1);
-	int32		max_tids = PG_GETARG_INT32(2);
-	int32	   *returned_tids = (int32 *) PG_GETARG_POINTER(3);
+	TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
+	int64		ntids;
 
 	if (GinIsNewKey(scan))
 		newScanKey(scan);
 
-	*returned_tids = 0;
-
 	if (GinIsVoidRes(scan))
-		PG_RETURN_BOOL(false);
+		PG_RETURN_INT64(0);
 
 	startScan(scan);
 
-	do
+	ntids = 0;
+	for (;;)
 	{
-		if (scanGetItem(scan, tids + *returned_tids))
-			(*returned_tids)++;
-		else
+		ItemPointerData iptr;
+
+		CHECK_FOR_INTERRUPTS();
+
+		if (!scanGetItem(scan, &iptr))
 			break;
-	} while (*returned_tids < max_tids);
+
+		tbm_add_tuples(tbm, &iptr, 1, false);
+		ntids++;
+	}
 
 	stopScan(scan);
 
-	PG_RETURN_BOOL(*returned_tids == max_tids);
+	PG_RETURN_INT64(ntids);
 }
 
 Datum
diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c
index c9f4118a93..5e973da886 100644
--- a/src/backend/access/gist/gistget.c
+++ b/src/backend/access/gist/gistget.c
@@ -16,13 +16,16 @@
 
 #include "access/gist_private.h"
 #include "executor/execdebug.h"
+#include "miscadmin.h"
 #include "pgstat.h"
 #include "utils/memutils.h"
 
 
 static OffsetNumber gistfindnext(IndexScanDesc scan, OffsetNumber n,
 			 ScanDirection dir);
-static int	gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, bool ignore_killed_tuples);
+static int64 gistnext(IndexScanDesc scan, ScanDirection dir,
+					  ItemPointer tid, TIDBitmap *tbm,
+					  bool ignore_killed_tuples);
 static bool gistindex_keytest(IndexTuple tuple, IndexScanDesc scan,
 				  OffsetNumber offset);
 
@@ -114,32 +117,37 @@ gistgettuple(PG_FUNCTION_ARGS)
 	 * tuples, continue looping until we find a non-killed tuple that matches
 	 * the search key.
 	 */
-	res = (gistnext(scan, dir, &tid, 1, scan->ignore_killed_tuples)) ? true : false;
+	res = (gistnext(scan, dir, &tid, NULL, scan->ignore_killed_tuples) > 0) ? true : false;
 
 	PG_RETURN_BOOL(res);
 }
 
 Datum
-gistgetmulti(PG_FUNCTION_ARGS)
+gistgetbitmap(PG_FUNCTION_ARGS)
 {
 	IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
-	ItemPointer tids = (ItemPointer) PG_GETARG_POINTER(1);
-	int32		max_tids = PG_GETARG_INT32(2);
-	int32	   *returned_tids = (int32 *) PG_GETARG_POINTER(3);
+	TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
+	int64	   ntids;
 
-	*returned_tids = gistnext(scan, ForwardScanDirection, tids, max_tids, false);
+	ntids = gistnext(scan, ForwardScanDirection, NULL, tbm, false);
 
-	PG_RETURN_BOOL(*returned_tids == max_tids);
+	PG_RETURN_INT64(ntids);
 }
 
 /*
- * Fetch a tuples that matchs the search key; this can be invoked
- * either to fetch the first such tuple or subsequent matching
- * tuples. Returns true iff a matching tuple was found.
+ * Fetch tuple(s) that match the search key; this can be invoked
+ * either to fetch the first such tuple or subsequent matching tuples.
+ *
+ * This function is used by both gistgettuple and gistgetbitmap. When
+ * invoked from gistgettuple, tbm is null and the next matching tuple
+ * is returned in *tid. When invoked from getbitmap, tid is null and
+ * all matching tuples are added to tbm. In both cases, the function
+ * result is the number of returned tuples.
  */
-static int
-gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
-		 int maxtids, bool ignore_killed_tuples)
+static int64
+gistnext(IndexScanDesc scan, ScanDirection dir,
+		 ItemPointer tid, TIDBitmap *tbm,
+		 bool ignore_killed_tuples)
 {
 	Page		p;
 	OffsetNumber n;
@@ -148,7 +156,7 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 	IndexTuple	it;
 	GISTPageOpaque opaque;
 	bool		resetoffset = false;
-	int			ntids = 0;
+	int64		ntids = 0;
 
 	so = (GISTScanOpaque) scan->opaque;
 
@@ -174,6 +182,8 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 
 	for (;;)
 	{
+		CHECK_FOR_INTERRUPTS();
+
 		/* First of all, we need lock buffer */
 		Assert(so->curbuf != InvalidBuffer);
 		LockBuffer(so->curbuf, GIST_SHARE);
@@ -285,20 +295,21 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 				 * return success. Note that we keep "curbuf" pinned so that
 				 * we can efficiently resume the index scan later.
 				 */
-
 				ItemPointerSet(&(so->curpos),
 							   BufferGetBlockNumber(so->curbuf), n);
 
 				if (!(ignore_killed_tuples && ItemIdIsDead(PageGetItemId(p, n))))
 				{
 					it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
-					tids[ntids] = scan->xs_ctup.t_self = it->t_tid;
 					ntids++;
-
-					if (ntids == maxtids)
+					if (tbm != NULL)
+						tbm_add_tuples(tbm, &it->t_tid, 1, false);
+					else 
 					{
+						*tid = scan->xs_ctup.t_self = it->t_tid;
+
 						LockBuffer(so->curbuf, GIST_UNLOCK);
-						return ntids;
+						return ntids; /* always 1 */
 					}
 				}
 			}
@@ -308,7 +319,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 				 * We've found an entry in an internal node whose key is
 				 * consistent with the search key, so push it to stack
 				 */
-
 				stk = (GISTSearchStack *) palloc(sizeof(GISTSearchStack));
 
 				it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
@@ -318,7 +328,6 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids,
 
 				stk->next = so->stack->next;
 				so->stack->next = stk;
-
 			}
 
 			if (ScanDirectionIsBackward(dir))
diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index 05f04ffa0e..1ea0ce49af 100644
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -22,6 +22,7 @@
 #include "access/hash.h"
 #include "catalog/index.h"
 #include "commands/vacuum.h"
+#include "miscadmin.h"
 #include "optimizer/cost.h"
 #include "optimizer/plancat.h"
 
@@ -275,72 +276,51 @@ hashgettuple(PG_FUNCTION_ARGS)
 
 
 /*
- *	hashgetmulti() -- get multiple tuples at once
- *
- * This is a somewhat generic implementation: it avoids lock reacquisition
- * overhead, but there's no smarts about picking especially good stopping
- * points such as index page boundaries.
+ *	hashgetbitmap() -- get all tuples at once
  */
 Datum
-hashgetmulti(PG_FUNCTION_ARGS)
+hashgetbitmap(PG_FUNCTION_ARGS)
 {
 	IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
-	ItemPointer tids = (ItemPointer) PG_GETARG_POINTER(1);
-	int32		max_tids = PG_GETARG_INT32(2);
-	int32	   *returned_tids = (int32 *) PG_GETARG_POINTER(3);
+	TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
 	HashScanOpaque so = (HashScanOpaque) scan->opaque;
-	Relation	rel = scan->indexRelation;
-	bool		res = true;
-	int32		ntids = 0;
+	bool		res;
+	int64		ntids = 0;
 
-	/*
-	 * We hold pin but not lock on current buffer while outside the hash AM.
-	 * Reacquire the read lock here.
-	 */
-	if (BufferIsValid(so->hashso_curbuf))
-		_hash_chgbufaccess(rel, so->hashso_curbuf, HASH_NOLOCK, HASH_READ);
+	res = _hash_first(scan, ForwardScanDirection);
 
-	while (ntids < max_tids)
+	while (res)
 	{
-		/*
-		 * Start scan, or advance to next tuple.
-		 */
-		if (ItemPointerIsValid(&(so->hashso_curpos)))
-			res = _hash_next(scan, ForwardScanDirection);
-		else
-			res = _hash_first(scan, ForwardScanDirection);
+		bool	add_tuple;
+
+		CHECK_FOR_INTERRUPTS();
 
 		/*
 		 * Skip killed tuples if asked to.
 		 */
 		if (scan->ignore_killed_tuples)
 		{
-			while (res)
-			{
-				Page		page;
-				OffsetNumber offnum;
-
-				offnum = ItemPointerGetOffsetNumber(&(so->hashso_curpos));
-				page = BufferGetPage(so->hashso_curbuf);
-				if (!ItemIdIsDead(PageGetItemId(page, offnum)))
-					break;
-				res = _hash_next(scan, ForwardScanDirection);
-			}
+			Page		page;
+			OffsetNumber offnum;
+
+			offnum = ItemPointerGetOffsetNumber(&(so->hashso_curpos));
+			page = BufferGetPage(so->hashso_curbuf);
+			add_tuple = !ItemIdIsDead(PageGetItemId(page, offnum));
 		}
+		else
+			add_tuple = true;
 
-		if (!res)
-			break;
 		/* Save tuple ID, and continue scanning */
-		tids[ntids] = scan->xs_ctup.t_self;
-		ntids++;
-	}
+		if (add_tuple) 
+		{
+			tbm_add_tuples(tbm, &scan->xs_ctup.t_self, 1, false);
+			ntids++;
+		}
 
-	/* Release read lock on current buffer, but keep it pinned */
-	if (BufferIsValid(so->hashso_curbuf))
-		_hash_chgbufaccess(rel, so->hashso_curbuf, HASH_READ, HASH_NOLOCK);
+		res = _hash_next(scan, ForwardScanDirection);
+	}
 
-	*returned_tids = ntids;
-	PG_RETURN_BOOL(res);
+	PG_RETURN_INT64(ntids);
 }
 
 
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index c9410642ce..3cccd1e783 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -88,7 +88,6 @@ RelationGetIndexScan(Relation indexRelation,
 	else
 		scan->keyData = NULL;
 
-	scan->is_multiscan = false; /* caller may change this */
 	scan->kill_prior_tuple = false;
 	scan->ignore_killed_tuples = true;	/* default setting */
 
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c
index 0929bb1ff3..754f8eaabb 100644
--- a/src/backend/access/index/indexam.c
+++ b/src/backend/access/index/indexam.c
@@ -14,14 +14,14 @@
  *		index_open		- open an index relation by relation OID
  *		index_close		- close an index relation
  *		index_beginscan - start a scan of an index with amgettuple
- *		index_beginscan_multi - start a scan of an index with amgetmulti
+ *		index_beginscan_bitmap - start a scan of an index with amgetbitmap
  *		index_rescan	- restart a scan of an index
  *		index_endscan	- end a scan
  *		index_insert	- insert an index tuple into a relation
  *		index_markpos	- mark a scan position
  *		index_restrpos	- restore a scan position
  *		index_getnext	- get the next tuple from a scan
- *		index_getmulti	- get multiple tuples from a scan
+ *		index_getbitmap	- get all tuples from a scan
  *		index_bulk_delete	- bulk deletion of index tuples
  *		index_vacuum_cleanup	- post-deletion cleanup of an index
  *		index_getprocid - get a support procedure OID
@@ -227,7 +227,6 @@ index_beginscan(Relation heapRelation,
 	 * Save additional parameters into the scandesc.  Everything else was set
 	 * up by RelationGetIndexScan.
 	 */
-	scan->is_multiscan = false;
 	scan->heapRelation = heapRelation;
 	scan->xs_snapshot = snapshot;
 
@@ -235,15 +234,15 @@ index_beginscan(Relation heapRelation,
 }
 
 /*
- * index_beginscan_multi - start a scan of an index with amgetmulti
+ * index_beginscan_bitmap - start a scan of an index with amgetbitmap
  *
  * As above, caller had better be holding some lock on the parent heap
  * relation, even though it's not explicitly mentioned here.
  */
 IndexScanDesc
-index_beginscan_multi(Relation indexRelation,
-					  Snapshot snapshot,
-					  int nkeys, ScanKey key)
+index_beginscan_bitmap(Relation indexRelation,
+					   Snapshot snapshot,
+					   int nkeys, ScanKey key)
 {
 	IndexScanDesc scan;
 
@@ -253,7 +252,6 @@ index_beginscan_multi(Relation indexRelation,
 	 * Save additional parameters into the scandesc.  Everything else was set
 	 * up by RelationGetIndexScan.
 	 */
-	scan->is_multiscan = true;
 	scan->xs_snapshot = snapshot;
 
 	return scan;
@@ -676,44 +674,39 @@ index_getnext_indexitem(IndexScanDesc scan,
 }
 
 /* ----------------
- *		index_getmulti - get multiple tuples from an index scan
+ *		index_getbitmap - get all tuples at once from an index scan
  *
- * Collects the TIDs of multiple heap tuples satisfying the scan keys.
+ * Adds the TIDs of all heap tuples satisfying the scan keys to a bitmap.
  * Since there's no interlock between the index scan and the eventual heap
  * access, this is only safe to use with MVCC-based snapshots: the heap
  * item slot could have been replaced by a newer tuple by the time we get
  * to it.
  *
- * A TRUE result indicates more calls should occur; a FALSE result says the
- * scan is done.  *returned_tids could be zero or nonzero in either case.
+ * Returns the number of matching tuples found.
  * ----------------
  */
-bool
-index_getmulti(IndexScanDesc scan,
-			   ItemPointer tids, int32 max_tids,
-			   int32 *returned_tids)
+int64
+index_getbitmap(IndexScanDesc scan, TIDBitmap *bitmap)
 {
 	FmgrInfo   *procedure;
-	bool		found;
+	int64		ntids;
 
 	SCAN_CHECKS;
-	GET_SCAN_PROCEDURE(amgetmulti);
+	GET_SCAN_PROCEDURE(amgetbitmap);
 
 	/* just make sure this is false... */
 	scan->kill_prior_tuple = false;
 
 	/*
-	 * have the am's getmulti proc do all the work.
+	 * have the am's getbitmap proc do all the work.
 	 */
-	found = DatumGetBool(FunctionCall4(procedure,
-									   PointerGetDatum(scan),
-									   PointerGetDatum(tids),
-									   Int32GetDatum(max_tids),
-									   PointerGetDatum(returned_tids)));
+	ntids = DatumGetInt64(FunctionCall2(procedure,
+										PointerGetDatum(scan),
+										PointerGetDatum(bitmap)));
 
-	pgstat_count_index_tuples(scan->indexRelation, *returned_tids);
+	pgstat_count_index_tuples(scan->indexRelation, ntids);
 
-	return found;
+	return ntids;
 }
 
 /* ----------------
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 5fd2b0f771..17a6185c91 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -22,6 +22,7 @@
 #include "access/nbtree.h"
 #include "catalog/index.h"
 #include "commands/vacuum.h"
+#include "miscadmin.h"
 #include "storage/freespace.h"
 #include "storage/lmgr.h"
 #include "utils/memutils.h"
@@ -278,42 +279,29 @@ btgettuple(PG_FUNCTION_ARGS)
 }
 
 /*
- * btgetmulti() -- get multiple tuples at once
- *
- * In the current implementation there seems no strong reason to stop at
- * index page boundaries; we just press on until we fill the caller's buffer
- * or run out of matches.
+ * btgetbitmap() -- gets all matching tuples, and adds them to a bitmap
  */
 Datum
-btgetmulti(PG_FUNCTION_ARGS)
+btgetbitmap(PG_FUNCTION_ARGS)
 {
 	IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
-	ItemPointer tids = (ItemPointer) PG_GETARG_POINTER(1);
-	int32		max_tids = PG_GETARG_INT32(2);
-	int32	   *returned_tids = (int32 *) PG_GETARG_POINTER(3);
+	TIDBitmap *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
 	BTScanOpaque so = (BTScanOpaque) scan->opaque;
-	bool		res = true;
-	int32		ntids = 0;
-
-	if (max_tids <= 0)			/* behave correctly in boundary case */
-		PG_RETURN_BOOL(true);
+	int64		ntids = 0;
+	ItemPointer heapTid;
 
-	/* If we haven't started the scan yet, fetch the first page & tuple. */
-	if (!BTScanPosIsValid(so->currPos))
+	/* Fetch the first page & tuple. */
+	if (!_bt_first(scan, ForwardScanDirection))
 	{
-		res = _bt_first(scan, ForwardScanDirection);
-		if (!res)
-		{
-			/* empty scan */
-			*returned_tids = ntids;
-			PG_RETURN_BOOL(res);
-		}
-		/* Save tuple ID, and continue scanning */
-		tids[ntids] = scan->xs_ctup.t_self;
-		ntids++;
+		/* empty scan */
+		PG_RETURN_INT64(0);
 	}
+	/* Save tuple ID, and continue scanning */
+	heapTid = &scan->xs_ctup.t_self;
+	tbm_add_tuples(tbm, heapTid, 1, false);
+	ntids++;
 
-	while (ntids < max_tids)
+	for (;;)
 	{
 		/*
 		 * Advance to next tuple within page.  This is the same as the easy
@@ -321,19 +309,20 @@ btgetmulti(PG_FUNCTION_ARGS)
 		 */
 		if (++so->currPos.itemIndex > so->currPos.lastItem)
 		{
+			CHECK_FOR_INTERRUPTS();
+
 			/* let _bt_next do the heavy lifting */
-			res = _bt_next(scan, ForwardScanDirection);
-			if (!res)
+			if (!_bt_next(scan, ForwardScanDirection))
 				break;
 		}
 
 		/* Save tuple ID, and continue scanning */
-		tids[ntids] = so->currPos.items[so->currPos.itemIndex].heapTid;
+		heapTid = &so->currPos.items[so->currPos.itemIndex].heapTid;
+		tbm_add_tuples(tbm, heapTid, 1, false);
 		ntids++;
 	}
 
-	*returned_tids = ntids;
-	PG_RETURN_BOOL(res);
+	PG_RETURN_INT64(ntids);
 }
 
 /*
diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index 672dd65bc2..4fe71adb71 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -206,7 +206,7 @@ BitmapHeapNext(BitmapHeapScanState *node)
 		 * If we are using lossy info, we have to recheck the qual conditions
 		 * at every tuple.
 		 */
-		if (tbmres->ntuples < 0)
+		if (tbmres->recheck)
 		{
 			econtext->ecxt_scantuple = slot;
 			ResetExprContext(econtext);
diff --git a/src/backend/executor/nodeBitmapIndexscan.c b/src/backend/executor/nodeBitmapIndexscan.c
index 88842ab319..1297fedd2a 100644
--- a/src/backend/executor/nodeBitmapIndexscan.c
+++ b/src/backend/executor/nodeBitmapIndexscan.c
@@ -37,11 +37,8 @@
 Node *
 MultiExecBitmapIndexScan(BitmapIndexScanState *node)
 {
-#define MAX_TIDS	1024
 	TIDBitmap  *tbm;
 	IndexScanDesc scandesc;
-	ItemPointerData tids[MAX_TIDS];
-	int32		ntids;
 	double		nTuples = 0;
 	bool		doscan;
 
@@ -91,23 +88,14 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
 	 */
 	while (doscan)
 	{
-		bool		more = index_getmulti(scandesc, tids, MAX_TIDS, &ntids);
-
-		if (ntids > 0)
-		{
-			tbm_add_tuples(tbm, tids, ntids);
-			nTuples += ntids;
-		}
+		nTuples += (double) index_getbitmap(scandesc, tbm);
 
 		CHECK_FOR_INTERRUPTS();
 
-		if (!more)
-		{
-			doscan = ExecIndexAdvanceArrayKeys(node->biss_ArrayKeys,
-											   node->biss_NumArrayKeys);
-			if (doscan)			/* reset index scan */
-				index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
-		}
+		doscan = ExecIndexAdvanceArrayKeys(node->biss_ArrayKeys,
+										   node->biss_NumArrayKeys);
+		if (doscan)			/* reset index scan */
+			index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
 	}
 
 	/* must provide our own instrumentation support */
@@ -321,10 +309,10 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
 	 * Initialize scan descriptor.
 	 */
 	indexstate->biss_ScanDesc =
-		index_beginscan_multi(indexstate->biss_RelationDesc,
-							  estate->es_snapshot,
-							  indexstate->biss_NumScanKeys,
-							  indexstate->biss_ScanKeys);
+		index_beginscan_bitmap(indexstate->biss_RelationDesc,
+							   estate->es_snapshot,
+							   indexstate->biss_NumScanKeys,
+							   indexstate->biss_ScanKeys);
 
 	/*
 	 * all done.
diff --git a/src/backend/nodes/tidbitmap.c b/src/backend/nodes/tidbitmap.c
index a1ac57f10b..ffc882f008 100644
--- a/src/backend/nodes/tidbitmap.c
+++ b/src/backend/nodes/tidbitmap.c
@@ -19,6 +19,15 @@
  * of lossiness.  In theory we could fall back to page ranges at some
  * point, but for now that seems useless complexity.
  *
+ * We also support the notion of candidate matches, or rechecking.  This
+ * means we know that a search need visit only some tuples on a page,
+ * but we are not certain that all of those tuples are real matches.
+ * So the eventual heap scan must recheck the quals for these tuples only,
+ * rather than rechecking the quals for all tuples on the page as in the
+ * lossy-bitmap case.  Rechecking can be specified when TIDs are inserted
+ * into a bitmap, and it can also happen internally when we AND a lossy
+ * and a non-lossy page.
+ *
  *
  * Copyright (c) 2003-2008, PostgreSQL Global Development Group
  *
@@ -81,11 +90,16 @@
  * have exact storage for the first page of a chunk if we are using
  * lossy storage for any page in the chunk's range, since the same
  * hashtable entry has to serve both purposes.
+ *
+ * recheck is used only on exact pages --- it indicates that although
+ * only the stated tuples need be checked, the full index qual condition
+ * must be checked for each (ie, these are candidate matches).
  */
 typedef struct PagetableEntry
 {
 	BlockNumber blockno;		/* page number (hashtable key) */
 	bool		ischunk;		/* T = lossy storage, F = exact */
+	bool		recheck;		/* should the tuples be rechecked? */
 	bitmapword	words[Max(WORDS_PER_PAGE, WORDS_PER_CHUNK)];
 } PagetableEntry;
 
@@ -244,9 +258,13 @@ tbm_free(TIDBitmap *tbm)
 
 /*
  * tbm_add_tuples - add some tuple IDs to a TIDBitmap
+ *
+ * If recheck is true, then the recheck flag will be set in the
+ * TBMIterateResult when any of these tuples are reported out.
  */
 void
-tbm_add_tuples(TIDBitmap *tbm, const ItemPointer tids, int ntids)
+tbm_add_tuples(TIDBitmap *tbm, const ItemPointer tids, int ntids,
+			   bool recheck)
 {
 	int			i;
 
@@ -280,6 +298,7 @@ tbm_add_tuples(TIDBitmap *tbm, const ItemPointer tids, int ntids)
 			bitnum = BITNUM(off - 1);
 		}
 		page->words[wordnum] |= ((bitmapword) 1 << bitnum);
+		page->recheck |= recheck;
 
 		if (tbm->nentries > tbm->maxentries)
 			tbm_lossify(tbm);
@@ -360,6 +379,7 @@ tbm_union_page(TIDBitmap *a, const PagetableEntry *bpage)
 			/* Both pages are exact, merge at the bit level */
 			for (wordnum = 0; wordnum < WORDS_PER_PAGE; wordnum++)
 				apage->words[wordnum] |= bpage->words[wordnum];
+			apage->recheck |= bpage->recheck;
 		}
 	}
 
@@ -471,22 +491,12 @@ tbm_intersect_page(TIDBitmap *a, PagetableEntry *apage, const TIDBitmap *b)
 	else if (tbm_page_is_lossy(b, apage->blockno))
 	{
 		/*
-		 * When the page is lossy in b, we have to mark it lossy in a too. We
-		 * know that no bits need be set in bitmap a, but we do not know which
-		 * ones should be cleared, and we have no API for "at most these
-		 * tuples need be checked".  (Perhaps it's worth adding that?)
-		 */
-		tbm_mark_page_lossy(a, apage->blockno);
-
-		/*
-		 * Note: tbm_mark_page_lossy will have removed apage from a, and may
-		 * have inserted a new lossy chunk instead.  We can continue the same
-		 * seq_search scan at the caller level, because it does not matter
-		 * whether we visit such a new chunk or not: it will have only the bit
-		 * for apage->blockno set, which is correct.
-		 *
-		 * We must return false here since apage was already deleted.
+		 * Some of the tuples in 'a' might not satisfy the quals for 'b',
+		 * but because the page 'b' is lossy, we don't know which ones. 
+		 * Therefore we mark 'a' as requiring rechecks, to indicate that
+		 * at most those tuples set in 'a' are matches.
 		 */
+		apage->recheck = true;
 		return false;
 	}
 	else
@@ -504,7 +514,9 @@ tbm_intersect_page(TIDBitmap *a, PagetableEntry *apage, const TIDBitmap *b)
 				if (apage->words[wordnum] != 0)
 					candelete = false;
 			}
+			apage->recheck |= bpage->recheck;
 		}
+		/* If there is no matching b page, we can just delete the a page */
 		return candelete;
 	}
 }
@@ -585,7 +597,9 @@ tbm_begin_iterate(TIDBitmap *tbm)
  * order.  If result->ntuples < 0, then the bitmap is "lossy" and failed to
  * remember the exact tuples to look at on this page --- the caller must
  * examine all tuples on the page and check if they meet the intended
- * condition.
+ * condition.  If result->recheck is true, only the indicated tuples need
+ * be examined, but the condition must be rechecked anyway.  (For ease of
+ * testing, recheck is always set true when ntuples < 0.)
  */
 TBMIterateResult *
 tbm_iterate(TIDBitmap *tbm)
@@ -638,6 +652,7 @@ tbm_iterate(TIDBitmap *tbm)
 			/* Return a lossy page indicator from the chunk */
 			output->blockno = chunk_blockno;
 			output->ntuples = -1;
+			output->recheck = true;
 			tbm->schunkbit++;
 			return output;
 		}
@@ -676,6 +691,7 @@ tbm_iterate(TIDBitmap *tbm)
 		}
 		output->blockno = page->blockno;
 		output->ntuples = ntuples;
+		output->recheck = page->recheck;
 		tbm->spageptr++;
 		return output;
 	}
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 40e11a26fb..bbf4ab5809 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -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 7684ec614e..20126bfe7c 100644
--- a/src/include/access/gin.h
+++ b/src/include/access/gin.h
@@ -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 4051546f49..1f83b54109 100644
--- a/src/include/access/gist_private.h
+++ b/src/include/access/gist_private.h
@@ -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 d41f7d0272..c1169cba30 100644
--- a/src/include/access/hash.h
+++ b/src/include/access/hash.h
@@ -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 26d254f36a..fb07512ea3 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -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 fba6dac604..b516adf21f 100644
--- a/src/include/access/relscan.h
+++ b/src/include/access/relscan.h
@@ -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 */
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 798ec85e1c..5f44d0e85d 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200804051
+#define CATALOG_VERSION_NO	200804101
 
 #endif
diff --git a/src/include/catalog/pg_am.h b/src/include/catalog/pg_am.h
index affc937f1d..7bf25ee3ce 100644
--- a/src/include/catalog/pg_am.h
+++ b/src/include/catalog/pg_am.h
@@ -51,7 +51,7 @@ CATALOG(pg_am,2601)
 	regproc		aminsert;		/* "insert this tuple" function */
 	regproc		ambeginscan;	/* "start new scan" function */
 	regproc		amgettuple;		/* "next valid tuple" function */
-	regproc		amgetmulti;		/* "fetch multiple tuples" function */
+	regproc		amgetbitmap;	/* "fetch all valid tuples" function */
 	regproc		amrescan;		/* "restart this scan" function */
 	regproc		amendscan;		/* "end this scan" function */
 	regproc		ammarkpos;		/* "mark current scan position" function */
@@ -89,7 +89,7 @@ typedef FormData_pg_am *Form_pg_am;
 #define Anum_pg_am_aminsert				12
 #define Anum_pg_am_ambeginscan			13
 #define Anum_pg_am_amgettuple			14
-#define Anum_pg_am_amgetmulti			15
+#define Anum_pg_am_amgetbitmap			15
 #define Anum_pg_am_amrescan				16
 #define Anum_pg_am_amendscan			17
 #define Anum_pg_am_ammarkpos			18
@@ -105,16 +105,16 @@ typedef FormData_pg_am *Form_pg_am;
  * ----------------
  */
 
-DATA(insert OID = 403 (  btree	5 1 t t t t t t f t btinsert btbeginscan btgettuple btgetmulti btrescan btendscan btmarkpos btrestrpos btbuild btbulkdelete btvacuumcleanup btcostestimate btoptions ));
+DATA(insert OID = 403 (  btree	5 1 t t t t t t f t btinsert btbeginscan btgettuple btgetbitmap btrescan btendscan btmarkpos btrestrpos btbuild btbulkdelete btvacuumcleanup btcostestimate btoptions ));
 DESCR("b-tree index access method");
 #define BTREE_AM_OID 403
-DATA(insert OID = 405 (  hash	1 1 f f f f f f f f hashinsert hashbeginscan hashgettuple hashgetmulti hashrescan hashendscan hashmarkpos hashrestrpos hashbuild hashbulkdelete hashvacuumcleanup hashcostestimate hashoptions ));
+DATA(insert OID = 405 (  hash	1 1 f f f f f f f f hashinsert hashbeginscan hashgettuple hashgetbitmap hashrescan hashendscan hashmarkpos hashrestrpos hashbuild hashbulkdelete hashvacuumcleanup hashcostestimate hashoptions ));
 DESCR("hash index access method");
 #define HASH_AM_OID 405
-DATA(insert OID = 783 (  gist	0 7 f f t t t t t t gistinsert gistbeginscan gistgettuple gistgetmulti gistrescan gistendscan gistmarkpos gistrestrpos gistbuild gistbulkdelete gistvacuumcleanup gistcostestimate gistoptions ));
+DATA(insert OID = 783 (  gist	0 7 f f t t t t t t gistinsert gistbeginscan gistgettuple gistgetbitmap gistrescan gistendscan gistmarkpos gistrestrpos gistbuild gistbulkdelete gistvacuumcleanup gistcostestimate gistoptions ));
 DESCR("GiST index access method");
 #define GIST_AM_OID 783
-DATA(insert OID = 2742 (  gin	0 4 f f f f f f t f gininsert ginbeginscan gingettuple gingetmulti ginrescan ginendscan ginmarkpos ginrestrpos ginbuild ginbulkdelete ginvacuumcleanup gincostestimate ginoptions ));
+DATA(insert OID = 2742 (  gin	0 4 f f f f f f t f gininsert ginbeginscan gingettuple gingetbitmap ginrescan ginendscan ginmarkpos ginrestrpos ginbuild ginbulkdelete ginvacuumcleanup gincostestimate ginoptions ));
 DESCR("GIN index access method");
 #define GIN_AM_OID 2742
 
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 622b05ce32..3a08c2cd43 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -655,7 +655,7 @@ DESCR("convert float4 to int4");
 
 DATA(insert OID = 330 (  btgettuple		   PGNSP PGUID 12 1 0 f f t f v 2 16 "2281 2281" _null_ _null_ _null_  btgettuple - _null_ _null_ ));
 DESCR("btree(internal)");
-DATA(insert OID = 636 (  btgetmulti		   PGNSP PGUID 12 1 0 f f t f v 4 16 "2281 2281 2281 2281" _null_ _null_ _null_  btgetmulti - _null_ _null_ ));
+DATA(insert OID = 636 (  btgetbitmap	   PGNSP PGUID 12 1 0 f f t f v 2 20 "2281 2281" _null_ _null_ _null_  btgetbitmap - _null_ _null_ ));
 DESCR("btree(internal)");
 DATA(insert OID = 331 (  btinsert		   PGNSP PGUID 12 1 0 f f t f v 6 16 "2281 2281 2281 2281 2281 2281" _null_ _null_ _null_	btinsert - _null_ _null_ ));
 DESCR("btree(internal)");
@@ -774,7 +774,7 @@ DESCR("convert char(n) to name");
 
 DATA(insert OID = 440 (  hashgettuple	   PGNSP PGUID 12 1 0 f f t f v 2 16 "2281 2281" _null_ _null_ _null_  hashgettuple - _null_ _null_ ));
 DESCR("hash(internal)");
-DATA(insert OID = 637 (  hashgetmulti	   PGNSP PGUID 12 1 0 f f t f v 4 16 "2281 2281 2281 2281" _null_ _null_ _null_  hashgetmulti - _null_ _null_ ));
+DATA(insert OID = 637 (  hashgetbitmap	   PGNSP PGUID 12 1 0 f f t f v 2 20 "2281 2281" _null_ _null_ _null_  hashgetbitmap - _null_ _null_ ));
 DESCR("hash(internal)");
 DATA(insert OID = 441 (  hashinsert		   PGNSP PGUID 12 1 0 f f t f v 6 16 "2281 2281 2281 2281 2281 2281" _null_ _null_ _null_	hashinsert - _null_ _null_ ));
 DESCR("hash(internal)");
@@ -1040,7 +1040,7 @@ DESCR("smaller of two");
 
 DATA(insert OID = 774 (  gistgettuple	   PGNSP PGUID 12 1 0 f f t f v 2 16 "2281 2281" _null_ _null_ _null_  gistgettuple - _null_ _null_ ));
 DESCR("gist(internal)");
-DATA(insert OID = 638 (  gistgetmulti	   PGNSP PGUID 12 1 0 f f t f v 4 16 "2281 2281 2281 2281" _null_ _null_ _null_  gistgetmulti - _null_ _null_ ));
+DATA(insert OID = 638 (  gistgetbitmap	   PGNSP PGUID 12 1 0 f f t f v 2 20 "2281 2281" _null_ _null_ _null_  gistgetbitmap - _null_ _null_ ));
 DESCR("gist(internal)");
 DATA(insert OID = 775 (  gistinsert		   PGNSP PGUID 12 1 0 f f t f v 6 16 "2281 2281 2281 2281 2281 2281" _null_ _null_ _null_	gistinsert - _null_ _null_ ));
 DESCR("gist(internal)");
@@ -3967,7 +3967,7 @@ DESCR("GiST support");
 /* GIN */
 DATA(insert OID = 2730 (  gingettuple	   PGNSP PGUID 12 1 0 f f t f v 2 16 "2281 2281" _null_ _null_ _null_  gingettuple - _null_ _null_ ));
 DESCR("gin(internal)");
-DATA(insert OID = 2731 (  gingetmulti	   PGNSP PGUID 12 1 0 f f t f v 4 16 "2281 2281 2281 2281" _null_ _null_ _null_  gingetmulti - _null_ _null_ ));
+DATA(insert OID = 2731 (  gingetbitmap	   PGNSP PGUID 12 1 0 f f t f v 2 20 "2281 2281" _null_ _null_ _null_  gingetbitmap - _null_ _null_ ));
 DESCR("gin(internal)");
 DATA(insert OID = 2732 (  gininsert		   PGNSP PGUID 12 1 0 f f t f v 6 16 "2281 2281 2281 2281 2281 2281" _null_ _null_ _null_	gininsert - _null_ _null_ ));
 DESCR("gin(internal)");
diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h
index 467cfdbfa3..56d6a0d8bc 100644
--- a/src/include/nodes/tidbitmap.h
+++ b/src/include/nodes/tidbitmap.h
@@ -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);
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index e0e7e054f7..607ac654d2 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -100,7 +100,7 @@ typedef struct RelationAmInfo
 	FmgrInfo	aminsert;
 	FmgrInfo	ambeginscan;
 	FmgrInfo	amgettuple;
-	FmgrInfo	amgetmulti;
+	FmgrInfo	amgetbitmap;
 	FmgrInfo	amrescan;
 	FmgrInfo	amendscan;
 	FmgrInfo	ammarkpos;
diff --git a/src/test/regress/expected/bitmapops.out b/src/test/regress/expected/bitmapops.out
new file mode 100644
index 0000000000..d88a76fe24
--- /dev/null
+++ b/src/test/regress/expected/bitmapops.out
@@ -0,0 +1,38 @@
+-- Test bitmap AND and OR
+-- Generate enough data that we can test the lossy bitmaps.
+-- There's 55 tuples per page in the table. 53 is just
+-- below 55, so that an index scan with qual a = constant
+-- will return at least one hit per page. 59 is just above
+-- 55, so that an index scan with qual b = constant will return
+-- hits on most but not all pages. 53 and 59 are prime, so that
+-- there's a maximum number of a,b combinations in the table.
+-- That allows us to test all the different combinations of
+-- lossy and non-lossy pages with the minimum amount of data
+CREATE TABLE bmscantest (a int, b int, t text);
+INSERT INTO bmscantest 
+  SELECT (r%53), (r%59), 'foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo'
+  FROM generate_series(1,70000) r;
+CREATE INDEX i_bmtest_a ON bmscantest(a);
+CREATE INDEX i_bmtest_b ON bmscantest(b);
+-- We want to use bitmapscans. With default settings, the planner currently
+-- chooses a bitmap scan for the queries below anyway, but let's make sure.
+set enable_indexscan=false;
+set enable_seqscan=false;
+-- Lower work_mem to trigger use of lossy bitmaps
+set work_mem = 64;
+-- Test bitmap-and.
+SELECT count(*) FROM bmscantest WHERE a = 1 AND b = 1;
+ count 
+-------
+    23
+(1 row)
+
+-- Test bitmap-or.
+SELECT count(*) FROM bmscantest WHERE a = 1 OR b = 1;
+ count 
+-------
+  2485
+(1 row)
+
+-- clean up
+DROP TABLE bmscantest;
diff --git a/src/test/regress/expected/create_index.out b/src/test/regress/expected/create_index.out
index b56078edf2..52ba630a56 100644
--- a/src/test/regress/expected/create_index.out
+++ b/src/test/regress/expected/create_index.out
@@ -174,7 +174,7 @@ RESET enable_bitmapscan;
 --
 SET enable_seqscan = OFF;
 SET enable_indexscan = ON;
-SET enable_bitmapscan = ON;
+SET enable_bitmapscan = OFF;
 CREATE INDEX intarrayidx ON array_index_op_test USING gin (i);
 SELECT * FROM array_index_op_test WHERE i @> '{32}' ORDER BY seqno;
  seqno |                i                |                                                                 t                                                                  
@@ -327,6 +327,95 @@ SELECT * FROM array_index_op_test WHERE t = '{AAAAAAAAAA646,A87088}' ORDER BY se
     96 | {23,97,43} | {AAAAAAAAAA646,A87088}
 (1 row)
 
+-- Repeat some of the above tests but exercising bitmapscans instead
+SET enable_indexscan = OFF;
+SET enable_bitmapscan = ON;
+SELECT * FROM array_index_op_test WHERE i @> '{32}' ORDER BY seqno;
+ seqno |                i                |                                                                 t                                                                  
+-------+---------------------------------+------------------------------------------------------------------------------------------------------------------------------------
+     6 | {39,35,5,94,17,92,60,32}        | {AAAAAAAAAAAAAAA35875,AAAAAAAAAAAAAAAA23657}
+    74 | {32}                            | {AAAAAAAAAAAAAAAA1729,AAAAAAAAAAAAA22860,AAAAAA99807,AAAAA17383,AAAAAAAAAAAAAAA67062,AAAAAAAAAAA15165,AAAAAAAAAAA50956}
+    77 | {97,15,32,17,55,59,18,37,50,39} | {AAAAAAAAAAAA67946,AAAAAA54032,AAAAAAAA81587,55847,AAAAAAAAAAAAAA28620,AAAAAAAAAAAAAAAAA43052,AAAAAA75463,AAAA49534,AAAAAAAA44066}
+    89 | {40,32,17,6,30,88}              | {AA44673,AAAAAAAAAAA6119,AAAAAAAAAAAAAAAA23657,AAAAAAAAAAAAAAAAAA47955,AAAAAAAAAAAAAAAA33598,AAAAAAAAAAA33576,AA44673}
+    98 | {38,34,32,89}                   | {AAAAAAAAAAAAAAAAAA71621,AAAA8857,AAAAAAAAAAAAAAAAAAA65037,AAAAAAAAAAAAAAAA31334,AAAAAAAAAA48845}
+   100 | {85,32,57,39,49,84,32,3,30}     | {AAAAAAA80240,AAAAAAAAAAAAAAAA1729,AAAAA60038,AAAAAAAAAAA92631,AAAAAAAA9523}
+(6 rows)
+
+SELECT * FROM array_index_op_test WHERE i && '{32}' ORDER BY seqno;
+ seqno |                i                |                                                                 t                                                                  
+-------+---------------------------------+------------------------------------------------------------------------------------------------------------------------------------
+     6 | {39,35,5,94,17,92,60,32}        | {AAAAAAAAAAAAAAA35875,AAAAAAAAAAAAAAAA23657}
+    74 | {32}                            | {AAAAAAAAAAAAAAAA1729,AAAAAAAAAAAAA22860,AAAAAA99807,AAAAA17383,AAAAAAAAAAAAAAA67062,AAAAAAAAAAA15165,AAAAAAAAAAA50956}
+    77 | {97,15,32,17,55,59,18,37,50,39} | {AAAAAAAAAAAA67946,AAAAAA54032,AAAAAAAA81587,55847,AAAAAAAAAAAAAA28620,AAAAAAAAAAAAAAAAA43052,AAAAAA75463,AAAA49534,AAAAAAAA44066}
+    89 | {40,32,17,6,30,88}              | {AA44673,AAAAAAAAAAA6119,AAAAAAAAAAAAAAAA23657,AAAAAAAAAAAAAAAAAA47955,AAAAAAAAAAAAAAAA33598,AAAAAAAAAAA33576,AA44673}
+    98 | {38,34,32,89}                   | {AAAAAAAAAAAAAAAAAA71621,AAAA8857,AAAAAAAAAAAAAAAAAAA65037,AAAAAAAAAAAAAAAA31334,AAAAAAAAAA48845}
+   100 | {85,32,57,39,49,84,32,3,30}     | {AAAAAAA80240,AAAAAAAAAAAAAAAA1729,AAAAA60038,AAAAAAAAAAA92631,AAAAAAAA9523}
+(6 rows)
+
+SELECT * FROM array_index_op_test WHERE i @> '{17}' ORDER BY seqno;
+ seqno |                i                |                                                                 t                                                                  
+-------+---------------------------------+------------------------------------------------------------------------------------------------------------------------------------
+     6 | {39,35,5,94,17,92,60,32}        | {AAAAAAAAAAAAAAA35875,AAAAAAAAAAAAAAAA23657}
+    12 | {17,99,18,52,91,72,0,43,96,23}  | {AAAAA33250,AAAAAAAAAAAAAAAAAAA85420,AAAAAAAAAAA33576}
+    15 | {17,14,16,63,67}                | {AA6416,AAAAAAAAAA646,AAAAA95309}
+    19 | {52,82,17,74,23,46,69,51,75}    | {AAAAAAAAAAAAA73084,AAAAA75968,AAAAAAAAAAAAAAAA14047,AAAAAAA80240,AAAAAAAAAAAAAAAAAAA1205,A68938}
+    53 | {38,17}                         | {AAAAAAAAAAA21658}
+    65 | {61,5,76,59,17}                 | {AAAAAA99807,AAAAA64741,AAAAAAAAAAA53908,AA21643,AAAAAAAAA10012}
+    77 | {97,15,32,17,55,59,18,37,50,39} | {AAAAAAAAAAAA67946,AAAAAA54032,AAAAAAAA81587,55847,AAAAAAAAAAAAAA28620,AAAAAAAAAAAAAAAAA43052,AAAAAA75463,AAAA49534,AAAAAAAA44066}
+    89 | {40,32,17,6,30,88}              | {AA44673,AAAAAAAAAAA6119,AAAAAAAAAAAAAAAA23657,AAAAAAAAAAAAAAAAAA47955,AAAAAAAAAAAAAAAA33598,AAAAAAAAAAA33576,AA44673}
+(8 rows)
+
+SELECT * FROM array_index_op_test WHERE i && '{17}' ORDER BY seqno;
+ seqno |                i                |                                                                 t                                                                  
+-------+---------------------------------+------------------------------------------------------------------------------------------------------------------------------------
+     6 | {39,35,5,94,17,92,60,32}        | {AAAAAAAAAAAAAAA35875,AAAAAAAAAAAAAAAA23657}
+    12 | {17,99,18,52,91,72,0,43,96,23}  | {AAAAA33250,AAAAAAAAAAAAAAAAAAA85420,AAAAAAAAAAA33576}
+    15 | {17,14,16,63,67}                | {AA6416,AAAAAAAAAA646,AAAAA95309}
+    19 | {52,82,17,74,23,46,69,51,75}    | {AAAAAAAAAAAAA73084,AAAAA75968,AAAAAAAAAAAAAAAA14047,AAAAAAA80240,AAAAAAAAAAAAAAAAAAA1205,A68938}
+    53 | {38,17}                         | {AAAAAAAAAAA21658}
+    65 | {61,5,76,59,17}                 | {AAAAAA99807,AAAAA64741,AAAAAAAAAAA53908,AA21643,AAAAAAAAA10012}
+    77 | {97,15,32,17,55,59,18,37,50,39} | {AAAAAAAAAAAA67946,AAAAAA54032,AAAAAAAA81587,55847,AAAAAAAAAAAAAA28620,AAAAAAAAAAAAAAAAA43052,AAAAAA75463,AAAA49534,AAAAAAAA44066}
+    89 | {40,32,17,6,30,88}              | {AA44673,AAAAAAAAAAA6119,AAAAAAAAAAAAAAAA23657,AAAAAAAAAAAAAAAAAA47955,AAAAAAAAAAAAAAAA33598,AAAAAAAAAAA33576,AA44673}
+(8 rows)
+
+SELECT * FROM array_index_op_test WHERE i @> '{32,17}' ORDER BY seqno;
+ seqno |                i                |                                                                 t                                                                  
+-------+---------------------------------+------------------------------------------------------------------------------------------------------------------------------------
+     6 | {39,35,5,94,17,92,60,32}        | {AAAAAAAAAAAAAAA35875,AAAAAAAAAAAAAAAA23657}
+    77 | {97,15,32,17,55,59,18,37,50,39} | {AAAAAAAAAAAA67946,AAAAAA54032,AAAAAAAA81587,55847,AAAAAAAAAAAAAA28620,AAAAAAAAAAAAAAAAA43052,AAAAAA75463,AAAA49534,AAAAAAAA44066}
+    89 | {40,32,17,6,30,88}              | {AA44673,AAAAAAAAAAA6119,AAAAAAAAAAAAAAAA23657,AAAAAAAAAAAAAAAAAA47955,AAAAAAAAAAAAAAAA33598,AAAAAAAAAAA33576,AA44673}
+(3 rows)
+
+SELECT * FROM array_index_op_test WHERE i && '{32,17}' ORDER BY seqno;
+ seqno |                i                |                                                                 t                                                                  
+-------+---------------------------------+------------------------------------------------------------------------------------------------------------------------------------
+     6 | {39,35,5,94,17,92,60,32}        | {AAAAAAAAAAAAAAA35875,AAAAAAAAAAAAAAAA23657}
+    12 | {17,99,18,52,91,72,0,43,96,23}  | {AAAAA33250,AAAAAAAAAAAAAAAAAAA85420,AAAAAAAAAAA33576}
+    15 | {17,14,16,63,67}                | {AA6416,AAAAAAAAAA646,AAAAA95309}
+    19 | {52,82,17,74,23,46,69,51,75}    | {AAAAAAAAAAAAA73084,AAAAA75968,AAAAAAAAAAAAAAAA14047,AAAAAAA80240,AAAAAAAAAAAAAAAAAAA1205,A68938}
+    53 | {38,17}                         | {AAAAAAAAAAA21658}
+    65 | {61,5,76,59,17}                 | {AAAAAA99807,AAAAA64741,AAAAAAAAAAA53908,AA21643,AAAAAAAAA10012}
+    74 | {32}                            | {AAAAAAAAAAAAAAAA1729,AAAAAAAAAAAAA22860,AAAAAA99807,AAAAA17383,AAAAAAAAAAAAAAA67062,AAAAAAAAAAA15165,AAAAAAAAAAA50956}
+    77 | {97,15,32,17,55,59,18,37,50,39} | {AAAAAAAAAAAA67946,AAAAAA54032,AAAAAAAA81587,55847,AAAAAAAAAAAAAA28620,AAAAAAAAAAAAAAAAA43052,AAAAAA75463,AAAA49534,AAAAAAAA44066}
+    89 | {40,32,17,6,30,88}              | {AA44673,AAAAAAAAAAA6119,AAAAAAAAAAAAAAAA23657,AAAAAAAAAAAAAAAAAA47955,AAAAAAAAAAAAAAAA33598,AAAAAAAAAAA33576,AA44673}
+    98 | {38,34,32,89}                   | {AAAAAAAAAAAAAAAAAA71621,AAAA8857,AAAAAAAAAAAAAAAAAAA65037,AAAAAAAAAAAAAAAA31334,AAAAAAAAAA48845}
+   100 | {85,32,57,39,49,84,32,3,30}     | {AAAAAAA80240,AAAAAAAAAAAAAAAA1729,AAAAA60038,AAAAAAAAAAA92631,AAAAAAAA9523}
+(11 rows)
+
+SELECT * FROM array_index_op_test WHERE i <@ '{38,34,32,89}' ORDER BY seqno;
+ seqno |       i       |                                                             t                                                              
+-------+---------------+----------------------------------------------------------------------------------------------------------------------------
+    40 | {34}          | {AAAAAAAAAAAAAA10611,AAAAAAAAAAAAAAAAAAA1205,AAAAAAAAAAA50956,AAAAAAAAAAAAAAAA31334,AAAAA70466,AAAAAAAA81587,AAAAAAA74623}
+    74 | {32}          | {AAAAAAAAAAAAAAAA1729,AAAAAAAAAAAAA22860,AAAAAA99807,AAAAA17383,AAAAAAAAAAAAAAA67062,AAAAAAAAAAA15165,AAAAAAAAAAA50956}
+    98 | {38,34,32,89} | {AAAAAAAAAAAAAAAAAA71621,AAAA8857,AAAAAAAAAAAAAAAAAAA65037,AAAAAAAAAAAAAAAA31334,AAAAAAAAAA48845}
+(3 rows)
+
+SELECT * FROM array_index_op_test WHERE i = '{47,77}' ORDER BY seqno;
+ seqno |    i    |                                                        t                                                        
+-------+---------+-----------------------------------------------------------------------------------------------------------------
+    95 | {47,77} | {AAAAAAAAAAAAAAAAA764,AAAAAAAAAAA74076,AAAAAAAAAA18107,AAAAA40681,AAAAAAAAAAAAAAA35875,AAAAA60038,AAAAAAA56483}
+(1 row)
+
 RESET enable_seqscan;
 RESET enable_indexscan;
 RESET enable_bitmapscan;
diff --git a/src/test/regress/expected/oidjoins.out b/src/test/regress/expected/oidjoins.out
index bd55dc24ae..c57721958f 100644
--- a/src/test/regress/expected/oidjoins.out
+++ b/src/test/regress/expected/oidjoins.out
@@ -65,12 +65,12 @@ WHERE	amgettuple != 0 AND
 ------+------------
 (0 rows)
 
-SELECT	ctid, amgetmulti 
+SELECT	ctid, amgetbitmap 
 FROM	pg_catalog.pg_am fk 
-WHERE	amgetmulti != 0 AND 
-	NOT EXISTS(SELECT 1 FROM pg_catalog.pg_proc pk WHERE pk.oid = fk.amgetmulti);
- ctid | amgetmulti 
-------+------------
+WHERE	amgetbitmap != 0 AND 
+	NOT EXISTS(SELECT 1 FROM pg_catalog.pg_proc pk WHERE pk.oid = fk.amgetbitmap);
+ ctid | amgetbitmap 
+------+-------------
 (0 rows)
 
 SELECT	ctid, amrescan 
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 0aba92cddc..389058f664 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -77,7 +77,7 @@ test: misc
 # ----------
 # Another group of parallel tests
 # ----------
-test: select_views portals_p2 rules foreign_key cluster dependency guc combocid tsearch tsdicts
+test: select_views portals_p2 rules foreign_key cluster dependency guc bitmapops combocid tsearch tsdicts
 
 # ----------
 # Another group of parallel tests
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 15f179a0c1..1263073fd0 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -92,6 +92,7 @@ test: foreign_key
 test: cluster
 test: dependency
 test: guc
+test: bitmapops
 test: combocid
 test: tsearch
 test: plancache
diff --git a/src/test/regress/sql/bitmapops.sql b/src/test/regress/sql/bitmapops.sql
new file mode 100644
index 0000000000..0b5477e8e1
--- /dev/null
+++ b/src/test/regress/sql/bitmapops.sql
@@ -0,0 +1,41 @@
+-- Test bitmap AND and OR
+
+
+-- Generate enough data that we can test the lossy bitmaps.
+
+-- There's 55 tuples per page in the table. 53 is just
+-- below 55, so that an index scan with qual a = constant
+-- will return at least one hit per page. 59 is just above
+-- 55, so that an index scan with qual b = constant will return
+-- hits on most but not all pages. 53 and 59 are prime, so that
+-- there's a maximum number of a,b combinations in the table.
+-- That allows us to test all the different combinations of
+-- lossy and non-lossy pages with the minimum amount of data
+
+CREATE TABLE bmscantest (a int, b int, t text);
+
+INSERT INTO bmscantest 
+  SELECT (r%53), (r%59), 'foooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo'
+  FROM generate_series(1,70000) r;
+
+CREATE INDEX i_bmtest_a ON bmscantest(a);
+CREATE INDEX i_bmtest_b ON bmscantest(b);
+
+-- We want to use bitmapscans. With default settings, the planner currently
+-- chooses a bitmap scan for the queries below anyway, but let's make sure.
+set enable_indexscan=false;
+set enable_seqscan=false;
+
+-- Lower work_mem to trigger use of lossy bitmaps
+set work_mem = 64;
+
+
+-- Test bitmap-and.
+SELECT count(*) FROM bmscantest WHERE a = 1 AND b = 1;
+
+-- Test bitmap-or.
+SELECT count(*) FROM bmscantest WHERE a = 1 OR b = 1;
+
+
+-- clean up
+DROP TABLE bmscantest;
diff --git a/src/test/regress/sql/create_index.sql b/src/test/regress/sql/create_index.sql
index 14f2f281ff..447c5df37a 100644
--- a/src/test/regress/sql/create_index.sql
+++ b/src/test/regress/sql/create_index.sql
@@ -143,7 +143,7 @@ RESET enable_bitmapscan;
 
 SET enable_seqscan = OFF;
 SET enable_indexscan = ON;
-SET enable_bitmapscan = ON;
+SET enable_bitmapscan = OFF;
 
 CREATE INDEX intarrayidx ON array_index_op_test USING gin (i);
 
@@ -167,6 +167,18 @@ SELECT * FROM array_index_op_test WHERE t && '{AAAAAAAA72908,AAAAAAAAAA646}' ORD
 SELECT * FROM array_index_op_test WHERE t <@ '{AAAAAAAA72908,AAAAAAAAAAAAAAAAAAA17075,AA88409,AAAAAAAAAAAAAAAAAA36842,AAAAAAA48038,AAAAAAAAAAAAAA10611}' ORDER BY seqno;
 SELECT * FROM array_index_op_test WHERE t = '{AAAAAAAAAA646,A87088}' ORDER BY seqno;
 
+-- Repeat some of the above tests but exercising bitmapscans instead
+SET enable_indexscan = OFF;
+SET enable_bitmapscan = ON;
+
+SELECT * FROM array_index_op_test WHERE i @> '{32}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i && '{32}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i @> '{17}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i && '{17}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i @> '{32,17}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i && '{32,17}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i <@ '{38,34,32,89}' ORDER BY seqno;
+SELECT * FROM array_index_op_test WHERE i = '{47,77}' ORDER BY seqno;
 
 RESET enable_seqscan;
 RESET enable_indexscan;
diff --git a/src/test/regress/sql/oidjoins.sql b/src/test/regress/sql/oidjoins.sql
index 773c2afe7f..7a072d4fd3 100644
--- a/src/test/regress/sql/oidjoins.sql
+++ b/src/test/regress/sql/oidjoins.sql
@@ -33,10 +33,10 @@ SELECT	ctid, amgettuple
 FROM	pg_catalog.pg_am fk 
 WHERE	amgettuple != 0 AND 
 	NOT EXISTS(SELECT 1 FROM pg_catalog.pg_proc pk WHERE pk.oid = fk.amgettuple);
-SELECT	ctid, amgetmulti 
+SELECT	ctid, amgetbitmap 
 FROM	pg_catalog.pg_am fk 
-WHERE	amgetmulti != 0 AND 
-	NOT EXISTS(SELECT 1 FROM pg_catalog.pg_proc pk WHERE pk.oid = fk.amgetmulti);
+WHERE	amgetbitmap != 0 AND 
+	NOT EXISTS(SELECT 1 FROM pg_catalog.pg_proc pk WHERE pk.oid = fk.amgetbitmap);
 SELECT	ctid, amrescan 
 FROM	pg_catalog.pg_am fk 
 WHERE	amrescan != 0 AND