Fix bug with page deletion. If inner page is removed and it tries to

remove page on next level linked from next inner page, ginScanToDelete()
wrongly sets parent page. Bug reveals when many item pointers from index
was deleted ( several hundred thousands).

Bug is discovered by hubert depesz lubaczewski 

Suppose, we need rc2 before release...

diff --git a/src/backend/access/gin/ginvacuum.c b/src/backend/access/gin/ginvacuum.c
index c3415ffe44ff2f30c57943a75d05aef215f1abb1..225dbc6047787e6a1239d8bbc097852e5adb18e0 100644 (file)
--- a/src/backend/access/gin/ginvacuum.c
+++ b/src/backend/access/gin/ginvacuum.c
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *         $PostgreSQL: pgsql/src/backend/access/gin/ginvacuum.c,v 1.8 2006/11/12 06:55:53 neilc Exp $
+ *         $PostgreSQL: pgsql/src/backend/access/gin/ginvacuum.c,v 1.9 2006/11/30 16:22:32 teodor Exp $
  *-------------------------------------------------------------------------
  */
 
@@ -265,6 +265,12 @@ ginDeletePage(GinVacuumState *gvs, BlockNumber deleteBlkno, BlockNumber leftBlkn
    }
 
    parentPage = BufferGetPage(pBuffer);
+#ifdef USE_ASSERT_CHECKING
+   do {
+       PostingItem *tod=(PostingItem *) GinDataPageGetItem(parentPage, myoff);
+       Assert( PostingItemGetBlockNumber(tod) == deleteBlkno );
+   } while(0);
+#endif
    PageDeletePostingItem(parentPage, myoff);
 
    page = BufferGetPage(dBuffer);
@@ -351,7 +357,8 @@ typedef struct DataPageDeleteStack
    struct DataPageDeleteStack *child;
    struct DataPageDeleteStack *parent;
 
-   BlockNumber blkno;
+   BlockNumber blkno; /* current block number */
+   BlockNumber leftBlkno; /* rightest non-deleted page on left */
    bool        isRoot;
 } DataPageDeleteStack;
 
@@ -377,7 +384,7 @@ ginScanToDelete(GinVacuumState *gvs, BlockNumber blkno, bool isRoot, DataPageDel
            me = (DataPageDeleteStack *) palloc0(sizeof(DataPageDeleteStack));
            me->parent = parent;
            parent->child = me;
-           me->blkno = InvalidBlockNumber;
+           me->leftBlkno = InvalidBlockNumber;
        }
        else
            me = parent->child;
@@ -392,6 +399,7 @@ ginScanToDelete(GinVacuumState *gvs, BlockNumber blkno, bool isRoot, DataPageDel
    {
        OffsetNumber i;
 
+       me->blkno = blkno;
        for (i = FirstOffsetNumber; i <= GinPageGetOpaque(page)->maxoff; i++)
        {
            PostingItem *pitem = (PostingItem *) GinDataPageGetItem(page, i);
@@ -403,13 +411,13 @@ ginScanToDelete(GinVacuumState *gvs, BlockNumber blkno, bool isRoot, DataPageDel
 
    if (GinPageGetOpaque(page)->maxoff < FirstOffsetNumber)
    {
-       if (!(me->blkno == InvalidBlockNumber && GinPageRightMost(page)))
+       if (!(me->leftBlkno == InvalidBlockNumber && GinPageRightMost(page)))
        {
            /* we never delete right most branch */
            Assert(!isRoot);
            if (GinPageGetOpaque(page)->maxoff < FirstOffsetNumber)
            {
-               ginDeletePage(gvs, blkno, me->blkno, me->parent->blkno, myoff, me->parent->isRoot);
+               ginDeletePage(gvs, blkno, me->leftBlkno, me->parent->blkno, myoff, me->parent->isRoot);
                meDelete = TRUE;
            }
        }
@@ -418,7 +426,7 @@ ginScanToDelete(GinVacuumState *gvs, BlockNumber blkno, bool isRoot, DataPageDel
    ReleaseBuffer(buffer);
 
    if (!meDelete)
-       me->blkno = blkno;
+       me->leftBlkno = blkno;
 
    return meDelete;
 }
@@ -438,7 +446,7 @@ ginVacuumPostingTree(GinVacuumState *gvs, BlockNumber rootBlkno)
    }
 
    memset(&root, 0, sizeof(DataPageDeleteStack));
-   root.blkno = rootBlkno;
+   root.leftBlkno = InvalidBlockNumber;
    root.isRoot = TRUE;
 
    vacuum_delay_point();