Fix GiST's killing tuple: GISTScanOpaque->curpos wasn't

correctly set. As result, killtuple() marks as dead
wrong tuple on page. Bug was introduced by me while fixing
possible duplicates during GiST index scan.

src/backend/access/gist/gistget.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.52.2.2 2008/08/23 10:43:58 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/gist/gistget.c,v 1.52.2.3 2008/10/22 12:56:25 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -153,7 +153,11 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
 	{
 		while( ntids < maxtids && so->curPageData < so->nPageData )
 		{
-			tids[ ntids ] = scan->xs_ctup.t_self = so->pageData[ so->curPageData ];
+			tids[ ntids ] = scan->xs_ctup.t_self = so->pageData[ so->curPageData ].heapPtr;
+			ItemPointerSet(&scan->currentItemData,
+							   BufferGetBlockNumber(so->curbuf), 
+							   so->pageData[ so->curPageData ].pageOffset);
+
 				
 			so->curPageData ++;
 			ntids++;
@@ -246,8 +250,13 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
 			{
 				while( ntids < maxtids && so->curPageData < so->nPageData )
 				{
-					tids[ ntids ] = scan->xs_ctup.t_self = so->pageData[ so->curPageData ];
+					tids[ ntids ] = scan->xs_ctup.t_self = 
+						so->pageData[ so->curPageData ].heapPtr;
 				
+					ItemPointerSet(&scan->currentItemData,
+								   BufferGetBlockNumber(so->curbuf), 
+								   so->pageData[ so->curPageData ].pageOffset);
+
 					so->curPageData ++;
 					ntids++;
 				}
@@ -291,13 +300,11 @@ gistnext(IndexScanDesc scan, ScanDirection dir, ItemPointer tids, int maxtids, b
 				 * we can efficiently resume the index scan later.
 				 */
 
-				ItemPointerSet(&(scan->currentItemData),
-							   BufferGetBlockNumber(so->curbuf), n);
-
 				if (!(ignore_killed_tuples && ItemIdDeleted(PageGetItemId(p, n))))
 				{
 					it = (IndexTuple) PageGetItem(p, PageGetItemId(p, n));
-					so->pageData[ so->nPageData ] = it->t_tid;
+					so->pageData[ so->nPageData ].heapPtr = it->t_tid;
+					so->pageData[ so->nPageData ].pageOffset = n;
 					so->nPageData ++;
 				}
 			}

src/backend/access/gist/gistscan.c

@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.61.2.1 2008/08/23 10:43:58 teodor Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/gist/gistscan.c,v 1.61.2.2 2008/10/22 12:56:25 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -185,7 +185,7 @@ gistmarkpos(PG_FUNCTION_ARGS)
 	so->markNPageData = so->nPageData;
 	so->markCurPageData = so->curPageData;
 	if ( so->markNPageData > 0 )
-		memcpy( so->markPageData, so->pageData, sizeof(ItemPointerData) * so->markNPageData );		
+		memcpy( so->markPageData, so->pageData, sizeof(MatchedItemPtr) * so->markNPageData );		
 
 	PG_RETURN_VOID();
 }
@@ -239,7 +239,7 @@ gistrestrpos(PG_FUNCTION_ARGS)
 	so->nPageData = so->markNPageData;
 	so->curPageData = so->markNPageData;
 	if ( so->markNPageData > 0 )
-		memcpy( so->pageData, so->markPageData, sizeof(ItemPointerData) * so->markNPageData );		
+		memcpy( so->pageData, so->markPageData, sizeof(MatchedItemPtr) * so->markNPageData );		
 
 	PG_RETURN_VOID();
 }

src/include/access/gist_private.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.8.2.1 2008/08/23 10:43:58 teodor Exp $
+ * $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.8.2.2 2008/10/22 12:56:25 teodor Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -60,6 +60,12 @@ typedef struct GISTSTATE
 	TupleDesc	tupdesc;
 } GISTSTATE;
 
+typedef struct MatchedItemPtr 
+{
+	ItemPointerData		heapPtr;
+	OffsetNumber		pageOffset; /* offset in index page */
+} MatchedItemPtr;
+
 /*
  *	When we're doing a scan, we need to keep track of the parent stack
  *	for the marked and current items.
@@ -74,10 +80,10 @@ typedef struct GISTScanOpaqueData
 	Buffer		curbuf;
 	Buffer		markbuf;
 
-	ItemPointerData pageData[BLCKSZ/sizeof(IndexTupleData)];
+	MatchedItemPtr 	pageData[BLCKSZ/sizeof(IndexTupleData)];
 	OffsetNumber    nPageData;
 	OffsetNumber    curPageData;
-	ItemPointerData markPageData[BLCKSZ/sizeof(IndexTupleData)];
+	MatchedItemPtr 	markPageData[BLCKSZ/sizeof(IndexTupleData)];
 	OffsetNumber    markNPageData;
 	OffsetNumber    markCurPageData;
 } GISTScanOpaqueData;