2 files changed, 50 insertions, 9 deletions

diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c
index f7f44b49aa3..b8aa9bca606 100644
--- a/src/backend/access/gist/gist.c
+++ b/src/backend/access/gist/gist.c
@@ -493,18 +493,36 @@ gistplacetopage(Relation rel, Size freespace, GISTSTATE *giststate,
 	else
 	{
 		/*
-		 * Enough space. We also get here if ntuples==0.
+		 * Enough space.  We always get here if ntup==0.
 		 */
 		START_CRIT_SECTION();
 
 		/*
-		 * While we delete only one tuple at once we could mix calls
-		 * PageIndexTupleDelete() here and PageIndexMultiDelete() in
-		 * gistRedoPageUpdateRecord()
+		 * Delete old tuple if any, then insert new tuple(s) if any.  If
+		 * possible, use the fast path of PageIndexTupleOverwrite.
 		 */
 		if (OffsetNumberIsValid(oldoffnum))
-			PageIndexTupleDelete(page, oldoffnum);
-		gistfillbuffer(page, itup, ntup, InvalidOffsetNumber);
+		{
+			if (ntup == 1)
+			{
+				/* One-for-one replacement, so use PageIndexTupleOverwrite */
+				if (!PageIndexTupleOverwrite(page, oldoffnum, (Item) *itup,
+											 IndexTupleSize(*itup)))
+					elog(ERROR, "failed to add item to index page in \"%s\"",
+						 RelationGetRelationName(rel));
+			}
+			else
+			{
+				/* Delete old, then append new tuple(s) to page */
+				PageIndexTupleDelete(page, oldoffnum);
+				gistfillbuffer(page, itup, ntup, InvalidOffsetNumber);
+			}
+		}
+		else
+		{
+			/* Just append new tuples at the end of the page */
+			gistfillbuffer(page, itup, ntup, InvalidOffsetNumber);
+		}
 
 		MarkBufferDirty(buffer);
 
diff --git a/src/backend/access/gist/gistxlog.c b/src/backend/access/gist/gistxlog.c
index 01c7ef7ea67..5853d7638e4 100644
--- a/src/backend/access/gist/gistxlog.c
+++ b/src/backend/access/gist/gistxlog.c
@@ -80,9 +80,31 @@ gistRedoPageUpdateRecord(XLogReaderState *record)
 
 		page = (Page) BufferGetPage(buffer);
 
-		/* Delete old tuples */
-		if (xldata->ntodelete > 0)
+		if (xldata->ntodelete == 1 && xldata->ntoinsert == 1)
 		{
+			/*
+			 * When replacing one tuple with one other tuple, we must use
+			 * PageIndexTupleOverwrite for consistency with gistplacetopage.
+			 */
+			OffsetNumber offnum = *((OffsetNumber *) data);
+			IndexTuple	itup;
+			Size		itupsize;
+
+			data += sizeof(OffsetNumber);
+			itup = (IndexTuple) data;
+			itupsize = IndexTupleSize(itup);
+			if (!PageIndexTupleOverwrite(page, offnum, (Item) itup, itupsize))
+				elog(ERROR, "failed to add item to GiST index page, size %d bytes",
+					 (int) itupsize);
+			data += itupsize;
+			/* should be nothing left after consuming 1 tuple */
+			Assert(data - begin == datalen);
+			/* update insertion count for assert check below */
+			ninserted++;
+		}
+		else if (xldata->ntodelete > 0)
+		{
+			/* Otherwise, delete old tuples if any */
 			OffsetNumber *todelete = (OffsetNumber *) data;
 
 			data += sizeof(OffsetNumber) * xldata->ntodelete;
@@ -92,7 +114,7 @@ gistRedoPageUpdateRecord(XLogReaderState *record)
 				GistMarkTuplesDeleted(page);
 		}
 
-		/* add tuples */
+		/* Add new tuples if any */
 		if (data - begin < datalen)
 		{
 			OffsetNumber off = (PageIsEmpty(page)) ? FirstOffsetNumber :
@@ -115,6 +137,7 @@ gistRedoPageUpdateRecord(XLogReaderState *record)
 			}
 		}
 
+		/* Check that XLOG record contained expected number of tuples */
 		Assert(ninserted == xldata->ntoinsert);
 
 		PageSetLSN(page, lsn);