Implement "fastupdate" support for GIN indexes, in which we try to accumulate

multiple index entries in a holding area before adding them to the main index
structure.  This helps because bulk insert is (usually) significantly faster
than retail insert for GIN.

This patch also removes GIN support for amgettuple-style index scans.  The
API defined for amgettuple is difficult to support with fastupdate, and
the previously committed partial-match feature didn't really work with
it either.  We might eventually figure a way to put back amgettuple
support, but it won't happen for 8.4.

catversion bumped because of change in GIN's pg_am entry, and because
the format of GIN indexes changed on-disk (there's a metapage now,
and possibly a pending list).

Teodor Sigaev

1 files changed, 20 insertions, 7 deletions

diff --git a/src/backend/access/gin/gindatapage.c b/src/backend/access/gin/gindatapage.c
index d0e426c6560..a872d44880c 100644
--- a/src/backend/access/gin/gindatapage.c
+++ b/src/backend/access/gin/gindatapage.c
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *			$PostgreSQL: pgsql/src/backend/access/gin/gindatapage.c,v 1.13 2009/01/01 17:23:34 momjian Exp $
+ *			$PostgreSQL: pgsql/src/backend/access/gin/gindatapage.c,v 1.14 2009/03/24 20:17:10 tgl Exp $
  *-------------------------------------------------------------------------
  */
 
@@ -43,8 +43,16 @@ MergeItemPointers(ItemPointerData *dst, ItemPointerData *a, uint32 na, ItemPoint
 
 	while (aptr - a < na && bptr - b < nb)
 	{
-		if (compareItemPointers(aptr, bptr) > 0)
+		int		cmp = compareItemPointers(aptr, bptr);
+
+		if (cmp > 0)
+			*dptr++ = *bptr++;
+		else if (cmp == 0)
+		{
+			/* we want only one copy of the identical items */
 			*dptr++ = *bptr++;
+			aptr++;
+		}
 		else
 			*dptr++ = *aptr++;
 	}
@@ -630,11 +638,16 @@ insertItemPointer(GinPostingTreeScan *gdi, ItemPointerData *items, uint32 nitem)
 		gdi->stack = ginFindLeafPage(&gdi->btree, gdi->stack);
 
 		if (gdi->btree.findItem(&(gdi->btree), gdi->stack))
-			elog(ERROR, "item pointer (%u,%d) already exists",
-			ItemPointerGetBlockNumber(gdi->btree.items + gdi->btree.curitem),
-				 ItemPointerGetOffsetNumber(gdi->btree.items + gdi->btree.curitem));
-
-		ginInsertValue(&(gdi->btree), gdi->stack);
+		{
+			/*
+			 * gdi->btree.items[gdi->btree.curitem] already exists in index
+			 */
+			gdi->btree.curitem++;
+			LockBuffer(gdi->stack->buffer, GIN_UNLOCK);
+			freeGinBtreeStack(gdi->stack);
+		}
+		else
+			ginInsertValue(&(gdi->btree), gdi->stack);
 
 		gdi->stack = NULL;
 	}