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Repair still another bug in the btree page split WAL reduction patch:

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it failed for splits of non-leaf pages because in such pages the first
data key on a page is suppressed, and so we can't just copy the first
key from the right page to reconstitute the left page's high key.
Problem found by Koichi Suzuki, patch by Heikki.
This commit is contained in:
Tom Lane
2007-11-16 19:53:50 +00:00
parent bb4a78c070
commit 93190c3098
3 changed files with 69 additions and 31 deletions
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50
src/backend/access/nbtree/nbtxlog.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.48 2007/11/15 22:25:15 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.49 2007/11/16 19:53:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -273,6 +273,8 @@ btree_xlog_split(bool onleft, bool isroot,
OffsetNumber newitemoff = 0;
Item newitem = NULL;
Size newitemsz = 0;
Item left_hikey = NULL;
Size left_hikeysz = 0;
reln = XLogOpenRelation(xlrec->node);
@ -289,6 +291,17 @@ btree_xlog_split(bool onleft, bool isroot,
datalen -= sizeof(BlockIdData);
forget_matching_split(xlrec->node, downlink, false);
/* Extract left hikey and its size (still assuming 16-bit alignment) */
if (!(record->xl_info & XLR_BKP_BLOCK_1))
{
/* We assume 16-bit alignment is enough for IndexTupleSize */
left_hikey = (Item) datapos;
left_hikeysz = MAXALIGN(IndexTupleSize(left_hikey));
datapos += left_hikeysz;
datalen -= left_hikeysz;
}
}
/* Extract newitem and newitemoff, if present */
@ -302,17 +315,13 @@ btree_xlog_split(bool onleft, bool isroot,
if (onleft && !(record->xl_info & XLR_BKP_BLOCK_1))
{
IndexTupleData itupdata;
/*
* We need to copy the tuple header to apply IndexTupleDSize, because
* of alignment considerations. However, we assume that PageAddItem
* doesn't care about the alignment of the newitem pointer it's given.
* We assume that 16-bit alignment is enough to apply IndexTupleSize
* (since it's fetching from a uint16 field) and also enough for
* PageAddItem to insert the tuple.
*/
newitem = datapos;
memcpy(&itupdata, datapos, sizeof(IndexTupleData));
newitemsz = IndexTupleDSize(itupdata);
newitemsz = MAXALIGN(newitemsz);
newitem = (Item) datapos;
newitemsz = MAXALIGN(IndexTupleSize(newitem));
datapos += newitemsz;
datalen -= newitemsz;
}
@ -333,6 +342,18 @@ btree_xlog_split(bool onleft, bool isroot,
_bt_restore_page(rpage, datapos, datalen);
/*
* On leaf level, the high key of the left page is equal to the
* first key on the right page.
*/
if (xlrec->level == 0)
{
ItemId hiItemId = PageGetItemId(rpage, P_FIRSTDATAKEY(ropaque));
left_hikey = PageGetItem(rpage, hiItemId);
left_hikeysz = ItemIdGetLength(hiItemId);
}
PageSetLSN(rpage, lsn);
PageSetTLI(rpage, ThisTimeLineID);
MarkBufferDirty(rbuf);
@ -360,8 +381,6 @@ btree_xlog_split(bool onleft, bool isroot,
OffsetNumber maxoff = PageGetMaxOffsetNumber(lpage);
OffsetNumber deletable[MaxOffsetNumber];
int ndeletable = 0;
ItemId hiItemId;
Item hiItem;
/*
* Remove the items from the left page that were copied to the
@ -394,11 +413,8 @@ btree_xlog_split(bool onleft, bool isroot,
elog(PANIC, "failed to add new item to left page after split");
}
/* Set high key equal to the first key on the right page */
hiItemId = PageGetItemId(rpage, P_FIRSTDATAKEY(ropaque));
hiItem = PageGetItem(rpage, hiItemId);
if (PageAddItem(lpage, hiItem, ItemIdGetLength(hiItemId),
/* Set high key */
if (PageAddItem(lpage, left_hikey, left_hikeysz,
P_HIKEY, false, false) == InvalidOffsetNumber)
elog(PANIC, "failed to add high key to left page after split");