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Commit93190c3

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Repair still another bug in the btree page split WAL reduction patch:
it failed for splits of non-leaf pages because in such pages the firstdata key on a page is suppressed, and so we can't just copy the firstkey from the right page to reconstitute the left page's high key.Problem found by Koichi Suzuki, patch by Heikki.
1 parentbb4a78c commit93190c3

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3 files changed

+69
-31
lines changed

3 files changed

+69
-31
lines changed

‎src/backend/access/nbtree/nbtinsert.c

Lines changed: 28 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.161 2007/11/15 21:14:32 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.162 2007/11/16 19:53:50 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -371,13 +371,13 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
371371
*removing any LP_DEAD tuples.
372372
*
373373
*On entry, *buf and *offsetptr point to the first legal position
374-
*where the new tuple could be inserted. The caller should hold an
375-
*exclusive lock on *buf. *offsetptr can also be set to
376-
*InvalidOffsetNumber, in which case the function will searchthe right
377-
*location within the page if needed. On exit, they point to the chosen
378-
*insert location. Iffindinsertloc decided to move right, the lock and
379-
*pin on the original page will be released and the new page returned to
380-
*the caller is exclusively locked instead.
374+
*where the new tuple could be inserted.The caller should hold an
375+
*exclusive lock on *buf.*offsetptr can also be set to
376+
*InvalidOffsetNumber, in which case the function will searchfor the
377+
*rightlocation within the page if needed.On exit, they point to the
378+
*choseninsert location.If_bt_findinsertloc decides to move right,
379+
*the lock andpin on the original page will be released and the new
380+
*page returned tothe caller is exclusively locked instead.
381381
*
382382
*newtup is the new tuple we're inserting, and scankey is an insertion
383383
*type scan key for it.
@@ -422,8 +422,6 @@ _bt_findinsertloc(Relation rel,
422422
"Consider a function index of an MD5 hash of the value, "
423423
"or use full text indexing.")));
424424

425-
426-
427425
/*----------
428426
* If we will need to split the page to put the item on this page,
429427
* check whether we can put the tuple somewhere to the right,
@@ -1004,7 +1002,7 @@ _bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
10041002
xl_btree_splitxlrec;
10051003
uint8xlinfo;
10061004
XLogRecPtrrecptr;
1007-
XLogRecDatardata[6];
1005+
XLogRecDatardata[7];
10081006
XLogRecData*lastrdata;
10091007

10101008
xlrec.node=rel->rd_node;
@@ -1020,15 +1018,32 @@ _bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
10201018

10211019
lastrdata=&rdata[0];
10221020

1023-
/* Log downlink on non-leaf pages. */
10241021
if (ropaque->btpo.level>0)
10251022
{
1023+
/* Log downlink on non-leaf pages */
10261024
lastrdata->next=lastrdata+1;
10271025
lastrdata++;
10281026

10291027
lastrdata->data= (char*)&newitem->t_tid.ip_blkid;
10301028
lastrdata->len=sizeof(BlockIdData);
10311029
lastrdata->buffer=InvalidBuffer;
1030+
1031+
/*
1032+
* We must also log the left page's high key, because the right
1033+
* page's leftmost key is suppressed on non-leaf levels. Show it
1034+
* as belonging to the left page buffer, so that it is not stored
1035+
* if XLogInsert decides it needs a full-page image of the left
1036+
* page.
1037+
*/
1038+
lastrdata->next=lastrdata+1;
1039+
lastrdata++;
1040+
1041+
itemid=PageGetItemId(origpage,P_HIKEY);
1042+
item= (IndexTuple)PageGetItem(origpage,itemid);
1043+
lastrdata->data= (char*)item;
1044+
lastrdata->len=MAXALIGN(IndexTupleSize(item));
1045+
lastrdata->buffer=buf;/* backup block 1 */
1046+
lastrdata->buffer_std= true;
10321047
}
10331048

10341049
/*
@@ -1057,7 +1072,7 @@ _bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
10571072
lastrdata->buffer=buf;/* backup block 1 */
10581073
lastrdata->buffer_std= true;
10591074
}
1060-
else
1075+
elseif (ropaque->btpo.level==0)
10611076
{
10621077
/*
10631078
* Although we don't need to WAL-log the new item, we still need

‎src/backend/access/nbtree/nbtxlog.c

Lines changed: 33 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.48 2007/11/15 22:25:15 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtxlog.c,v 1.49 2007/11/16 19:53:50 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -273,6 +273,8 @@ btree_xlog_split(bool onleft, bool isroot,
273273
OffsetNumbernewitemoff=0;
274274
Itemnewitem=NULL;
275275
Sizenewitemsz=0;
276+
Itemleft_hikey=NULL;
277+
Sizeleft_hikeysz=0;
276278

277279
reln=XLogOpenRelation(xlrec->node);
278280

@@ -289,6 +291,17 @@ btree_xlog_split(bool onleft, bool isroot,
289291
datalen-=sizeof(BlockIdData);
290292

291293
forget_matching_split(xlrec->node,downlink, false);
294+
295+
/* Extract left hikey and its size (still assuming 16-bit alignment) */
296+
if (!(record->xl_info&XLR_BKP_BLOCK_1))
297+
{
298+
/* We assume 16-bit alignment is enough for IndexTupleSize */
299+
left_hikey= (Item)datapos;
300+
left_hikeysz=MAXALIGN(IndexTupleSize(left_hikey));
301+
302+
datapos+=left_hikeysz;
303+
datalen-=left_hikeysz;
304+
}
292305
}
293306

294307
/* Extract newitem and newitemoff, if present */
@@ -302,17 +315,13 @@ btree_xlog_split(bool onleft, bool isroot,
302315

303316
if (onleft&& !(record->xl_info&XLR_BKP_BLOCK_1))
304317
{
305-
IndexTupleDataitupdata;
306-
307318
/*
308-
* Weneed to copy the tuple header to applyIndexTupleDSize, because
309-
*of alignment considerations. However, we assume that PageAddItem
310-
*doesn't care about thealignment of the newitem pointer it's given.
319+
* Weassume that 16-bit alignment is enough to applyIndexTupleSize
320+
*(since it's fetching from a uint16 field) and also enough for
321+
*PageAddItem to insert thetuple.
311322
*/
312-
newitem=datapos;
313-
memcpy(&itupdata,datapos,sizeof(IndexTupleData));
314-
newitemsz=IndexTupleDSize(itupdata);
315-
newitemsz=MAXALIGN(newitemsz);
323+
newitem= (Item)datapos;
324+
newitemsz=MAXALIGN(IndexTupleSize(newitem));
316325
datapos+=newitemsz;
317326
datalen-=newitemsz;
318327
}
@@ -333,6 +342,18 @@ btree_xlog_split(bool onleft, bool isroot,
333342

334343
_bt_restore_page(rpage,datapos,datalen);
335344

345+
/*
346+
* On leaf level, the high key of the left page is equal to the
347+
* first key on the right page.
348+
*/
349+
if (xlrec->level==0)
350+
{
351+
ItemIdhiItemId=PageGetItemId(rpage,P_FIRSTDATAKEY(ropaque));
352+
353+
left_hikey=PageGetItem(rpage,hiItemId);
354+
left_hikeysz=ItemIdGetLength(hiItemId);
355+
}
356+
336357
PageSetLSN(rpage,lsn);
337358
PageSetTLI(rpage,ThisTimeLineID);
338359
MarkBufferDirty(rbuf);
@@ -360,8 +381,6 @@ btree_xlog_split(bool onleft, bool isroot,
360381
OffsetNumbermaxoff=PageGetMaxOffsetNumber(lpage);
361382
OffsetNumberdeletable[MaxOffsetNumber];
362383
intndeletable=0;
363-
ItemIdhiItemId;
364-
ItemhiItem;
365384

366385
/*
367386
* Remove the items from the left page that were copied to the
@@ -394,11 +413,8 @@ btree_xlog_split(bool onleft, bool isroot,
394413
elog(PANIC,"failed to add new item to left page after split");
395414
}
396415

397-
/* Set high key equal to the first key on the right page */
398-
hiItemId=PageGetItemId(rpage,P_FIRSTDATAKEY(ropaque));
399-
hiItem=PageGetItem(rpage,hiItemId);
400-
401-
if (PageAddItem(lpage,hiItem,ItemIdGetLength(hiItemId),
416+
/* Set high key */
417+
if (PageAddItem(lpage,left_hikey,left_hikeysz,
402418
P_HIKEY, false, false)==InvalidOffsetNumber)
403419
elog(PANIC,"failed to add high key to left page after split");
404420

‎src/include/access/nbtree.h

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.114 2007/11/15 21:14:42 momjian Exp $
10+
* $PostgreSQL: pgsql/src/include/access/nbtree.h,v 1.115 2007/11/16 19:53:50 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -289,8 +289,15 @@ typedef struct xl_btree_split
289289
* than BlockNumber for alignment reasons: SizeOfBtreeSplit is only 16-bit
290290
* aligned.)
291291
*
292+
* If level > 0, an IndexTuple representing the HIKEY of the left page
293+
* follows. We don't need this on leaf pages, because it's the same
294+
* as the leftmost key in the new right page. Also, it's suppressed if
295+
* XLogInsert chooses to store the left page's whole page image.
296+
*
292297
* In the _L variants, next are OffsetNumber newitemoff and the new item.
293298
* (In the _R variants, the new item is one of the right page's tuples.)
299+
* The new item, but not newitemoff, is suppressed if XLogInsert chooses
300+
* to store the left page's whole page image.
294301
*
295302
* Last are the right page's tuples in the form used by _bt_restore_page.
296303
*/

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