Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit634e148

Browse files
committed
Fix multiple problems in WAL replay.
Most of the replay functions for WAL record types that modify more thanone page failed to ensure that those pages were locked correctly to ensurethat concurrent queries could not see inconsistent page states. This isa hangover from coding decisions made long before Hot Standby was added,when it was hardly necessary to acquire buffer locks during WAL replayat all, let alone hold them for carefully-chosen periods.The key problem was that RestoreBkpBlocks was written to hold lock on eachpage restored from a full-page image for only as long as it took to updatethat page. This was guaranteed to break any WAL replay function in whichthere was any update-ordering constraint between pages, because even if thenominal order of the pages is the right one, any mixture of full-page andnon-full-page updates in the same record would result in out-of-orderupdates. Moreover, it wouldn't work for situations where there's arequirement to maintain lock on one page while updating another. Failureto honor an update ordering constraint in this way is thought to be thecause of bug #7648 from Daniel Farina: what seems to have happened thereis that a btree page being split was rewritten from a full-page imagebefore the new right sibling page was written, and because lock on theoriginal page was not maintained it was possible for hot standby queries totry to traverse the page's right-link to the not-yet-existing sibling page.To fix, get rid of RestoreBkpBlocks as such, and instead create a newfunction RestoreBackupBlock that restores just one full-page image at atime. This function can be invoked by WAL replay functions at the pointswhere they would otherwise perform non-full-page updates; in this way, thephysical order of page updates remains the same no matter which pages arereplaced by full-page images. We can then further adjust the logic inindividual replay functions if it is necessary to hold buffer locksfor overlapping periods. A side benefit is that we can simplify thehandling of concurrency conflict resolution by moving that code into therecord-type-specfic functions; there's no more need to contort the codelayout to keep conflict resolution in front of the RestoreBkpBlocks call.In connection with that, standardize on zero-based numbering rather thanone-based numbering for referencing the full-page images. In HEAD, Iremoved the macros XLR_BKP_BLOCK_1 through XLR_BKP_BLOCK_4. They arestill there in the header files in previous branches, but are no longerused by the code.In addition, fix some other bugs identified in the course of making thesechanges:spgRedoAddNode could fail to update the parent downlink at all, if theparent tuple is in the same page as either the old or new split tuple andwe're not doing a full-page image: it would get fooled by the LSN havingbeen advanced already. This would result in permanent index corruption,not just transient failure of concurrent queries.Also, ginHeapTupleFastInsert's "merge lists" case failed to mark the oldtail page as a candidate for a full-page image; in the worst case thiscould result in torn-page corruption.heap_xlog_freeze() was inconsistent about using a cleanup lock or plainexclusive lock: it did the former in the normal path but the latter for afull-page image. A plain exclusive lock seems sufficient, so change tothat.Also, remove gistRedoPageDeleteRecord(), which has been dead code sinceVACUUM FULL was rewritten.Back-patch to 9.0, where hot standby was introduced. Note however that 9.0had a significantly different WAL-logging scheme for GIST index updates,and it doesn't appear possible to make that scheme safe for concurrent hotstandby queries, because it can leave inconsistent states in the index evenbetween WAL records. Given the lack of complaints from the field, we won'twork too hard on fixing that branch.
1 parentf8ffe62 commit634e148

File tree

8 files changed

+529
-319
lines changed

8 files changed

+529
-319
lines changed

‎src/backend/access/gin/ginfast.c

Lines changed: 9 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -291,7 +291,7 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
291291
if (metadata->head==InvalidBlockNumber)
292292
{
293293
/*
294-
* Main list is empty, so justcopy sublistinto main list
294+
* Main list is empty, so justinsert sublistas main list
295295
*/
296296
START_CRIT_SECTION();
297297

@@ -314,6 +314,14 @@ ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector)
314314
LockBuffer(buffer,GIN_EXCLUSIVE);
315315
page=BufferGetPage(buffer);
316316

317+
rdata[0].next=rdata+1;
318+
319+
rdata[1].buffer=buffer;
320+
rdata[1].buffer_std= true;
321+
rdata[1].data=NULL;
322+
rdata[1].len=0;
323+
rdata[1].next=NULL;
324+
317325
Assert(GinPageGetOpaque(page)->rightlink==InvalidBlockNumber);
318326

319327
START_CRIT_SECTION();

‎src/backend/access/gin/ginxlog.c

Lines changed: 85 additions & 37 deletions
Original file line numberDiff line numberDiff line change
@@ -78,6 +78,9 @@ ginRedoCreateIndex(XLogRecPtr lsn, XLogRecord *record)
7878
MetaBuffer;
7979
Pagepage;
8080

81+
/* Backup blocks are not used in create_index records */
82+
Assert(!(record->xl_info&XLR_BKP_BLOCK_MASK));
83+
8184
MetaBuffer=XLogReadBuffer(*node,GIN_METAPAGE_BLKNO, true);
8285
Assert(BufferIsValid(MetaBuffer));
8386
page= (Page)BufferGetPage(MetaBuffer);
@@ -110,6 +113,9 @@ ginRedoCreatePTree(XLogRecPtr lsn, XLogRecord *record)
110113
Bufferbuffer;
111114
Pagepage;
112115

116+
/* Backup blocks are not used in create_ptree records */
117+
Assert(!(record->xl_info&XLR_BKP_BLOCK_MASK));
118+
113119
buffer=XLogReadBuffer(data->node,data->blkno, true);
114120
Assert(BufferIsValid(buffer));
115121
page= (Page)BufferGetPage(buffer);
@@ -160,9 +166,12 @@ ginRedoInsert(XLogRecPtr lsn, XLogRecord *record)
160166
}
161167
}
162168

163-
/* nothing else to do if page was backed up */
164-
if (record->xl_info&XLR_BKP_BLOCK_1)
169+
/* If we have a full-page image, restore it and we're done */
170+
if (record->xl_info&XLR_BKP_BLOCK(0))
171+
{
172+
(void)RestoreBackupBlock(lsn,record,0, false, false);
165173
return;
174+
}
166175

167176
buffer=XLogReadBuffer(data->node,data->blkno, false);
168177
if (!BufferIsValid(buffer))
@@ -257,6 +266,9 @@ ginRedoSplit(XLogRecPtr lsn, XLogRecord *record)
257266
if (data->isData)
258267
flags |=GIN_DATA;
259268

269+
/* Backup blocks are not used in split records */
270+
Assert(!(record->xl_info&XLR_BKP_BLOCK_MASK));
271+
260272
lbuffer=XLogReadBuffer(data->node,data->lblkno, true);
261273
Assert(BufferIsValid(lbuffer));
262274
lpage= (Page)BufferGetPage(lbuffer);
@@ -370,9 +382,12 @@ ginRedoVacuumPage(XLogRecPtr lsn, XLogRecord *record)
370382
Bufferbuffer;
371383
Pagepage;
372384

373-
/* nothing to do if page was backed up (and no info to do it with) */
374-
if (record->xl_info&XLR_BKP_BLOCK_1)
385+
/* If we have a full-page image, restore it and we're done */
386+
if (record->xl_info&XLR_BKP_BLOCK(0))
387+
{
388+
(void)RestoreBackupBlock(lsn,record,0, false, false);
375389
return;
390+
}
376391

377392
buffer=XLogReadBuffer(data->node,data->blkno, false);
378393
if (!BufferIsValid(buffer))
@@ -421,63 +436,74 @@ static void
421436
ginRedoDeletePage(XLogRecPtrlsn,XLogRecord*record)
422437
{
423438
ginxlogDeletePage*data= (ginxlogDeletePage*)XLogRecGetData(record);
424-
Bufferbuffer;
439+
Bufferdbuffer;
440+
Bufferpbuffer;
441+
Bufferlbuffer;
425442
Pagepage;
426443

427-
if (!(record->xl_info&XLR_BKP_BLOCK_1))
444+
if (record->xl_info&XLR_BKP_BLOCK(0))
445+
dbuffer=RestoreBackupBlock(lsn,record,0, false, true);
446+
else
428447
{
429-
buffer=XLogReadBuffer(data->node,data->blkno, false);
430-
if (BufferIsValid(buffer))
448+
dbuffer=XLogReadBuffer(data->node,data->blkno, false);
449+
if (BufferIsValid(dbuffer))
431450
{
432-
page=BufferGetPage(buffer);
451+
page=BufferGetPage(dbuffer);
433452
if (!XLByteLE(lsn,PageGetLSN(page)))
434453
{
435454
Assert(GinPageIsData(page));
436455
GinPageGetOpaque(page)->flags=GIN_DELETED;
437456
PageSetLSN(page,lsn);
438457
PageSetTLI(page,ThisTimeLineID);
439-
MarkBufferDirty(buffer);
458+
MarkBufferDirty(dbuffer);
440459
}
441-
UnlockReleaseBuffer(buffer);
442460
}
443461
}
444462

445-
if (!(record->xl_info&XLR_BKP_BLOCK_2))
463+
if (record->xl_info&XLR_BKP_BLOCK(1))
464+
pbuffer=RestoreBackupBlock(lsn,record,1, false, true);
465+
else
446466
{
447-
buffer=XLogReadBuffer(data->node,data->parentBlkno, false);
448-
if (BufferIsValid(buffer))
467+
pbuffer=XLogReadBuffer(data->node,data->parentBlkno, false);
468+
if (BufferIsValid(pbuffer))
449469
{
450-
page=BufferGetPage(buffer);
470+
page=BufferGetPage(pbuffer);
451471
if (!XLByteLE(lsn,PageGetLSN(page)))
452472
{
453473
Assert(GinPageIsData(page));
454474
Assert(!GinPageIsLeaf(page));
455475
GinPageDeletePostingItem(page,data->parentOffset);
456476
PageSetLSN(page,lsn);
457477
PageSetTLI(page,ThisTimeLineID);
458-
MarkBufferDirty(buffer);
478+
MarkBufferDirty(pbuffer);
459479
}
460-
UnlockReleaseBuffer(buffer);
461480
}
462481
}
463482

464-
if (!(record->xl_info&XLR_BKP_BLOCK_3)&&data->leftBlkno!=InvalidBlockNumber)
483+
if (record->xl_info&XLR_BKP_BLOCK(2))
484+
(void)RestoreBackupBlock(lsn,record,2, false, false);
485+
elseif (data->leftBlkno!=InvalidBlockNumber)
465486
{
466-
buffer=XLogReadBuffer(data->node,data->leftBlkno, false);
467-
if (BufferIsValid(buffer))
487+
lbuffer=XLogReadBuffer(data->node,data->leftBlkno, false);
488+
if (BufferIsValid(lbuffer))
468489
{
469-
page=BufferGetPage(buffer);
490+
page=BufferGetPage(lbuffer);
470491
if (!XLByteLE(lsn,PageGetLSN(page)))
471492
{
472493
Assert(GinPageIsData(page));
473494
GinPageGetOpaque(page)->rightlink=data->rightLink;
474495
PageSetLSN(page,lsn);
475496
PageSetTLI(page,ThisTimeLineID);
476-
MarkBufferDirty(buffer);
497+
MarkBufferDirty(lbuffer);
477498
}
478-
UnlockReleaseBuffer(buffer);
499+
UnlockReleaseBuffer(lbuffer);
479500
}
480501
}
502+
503+
if (BufferIsValid(pbuffer))
504+
UnlockReleaseBuffer(pbuffer);
505+
if (BufferIsValid(dbuffer))
506+
UnlockReleaseBuffer(dbuffer);
481507
}
482508

483509
staticvoid
@@ -506,7 +532,9 @@ ginRedoUpdateMetapage(XLogRecPtr lsn, XLogRecord *record)
506532
/*
507533
* insert into tail page
508534
*/
509-
if (!(record->xl_info&XLR_BKP_BLOCK_1))
535+
if (record->xl_info&XLR_BKP_BLOCK(0))
536+
(void)RestoreBackupBlock(lsn,record,0, false, false);
537+
else
510538
{
511539
buffer=XLogReadBuffer(data->node,data->metadata.tail, false);
512540
if (BufferIsValid(buffer))
@@ -554,20 +582,25 @@ ginRedoUpdateMetapage(XLogRecPtr lsn, XLogRecord *record)
554582
/*
555583
* New tail
556584
*/
557-
buffer=XLogReadBuffer(data->node,data->prevTail, false);
558-
if (BufferIsValid(buffer))
585+
if (record->xl_info&XLR_BKP_BLOCK(0))
586+
(void)RestoreBackupBlock(lsn,record,0, false, false);
587+
else
559588
{
560-
Pagepage=BufferGetPage(buffer);
561-
562-
if (!XLByteLE(lsn,PageGetLSN(page)))
589+
buffer=XLogReadBuffer(data->node,data->prevTail, false);
590+
if (BufferIsValid(buffer))
563591
{
564-
GinPageGetOpaque(page)->rightlink=data->newRightlink;
592+
Pagepage=BufferGetPage(buffer);
565593

566-
PageSetLSN(page,lsn);
567-
PageSetTLI(page,ThisTimeLineID);
568-
MarkBufferDirty(buffer);
594+
if (!XLByteLE(lsn,PageGetLSN(page)))
595+
{
596+
GinPageGetOpaque(page)->rightlink=data->newRightlink;
597+
598+
PageSetLSN(page,lsn);
599+
PageSetTLI(page,ThisTimeLineID);
600+
MarkBufferDirty(buffer);
601+
}
602+
UnlockReleaseBuffer(buffer);
569603
}
570-
UnlockReleaseBuffer(buffer);
571604
}
572605
}
573606

@@ -586,8 +619,12 @@ ginRedoInsertListPage(XLogRecPtr lsn, XLogRecord *record)
586619
tupsize;
587620
IndexTupletuples= (IndexTuple) (XLogRecGetData(record)+sizeof(ginxlogInsertListPage));
588621

589-
if (record->xl_info&XLR_BKP_BLOCK_1)
622+
/* If we have a full-page image, restore it and we're done */
623+
if (record->xl_info&XLR_BKP_BLOCK(0))
624+
{
625+
(void)RestoreBackupBlock(lsn,record,0, false, false);
590626
return;
627+
}
591628

592629
buffer=XLogReadBuffer(data->node,data->blkno, true);
593630
Assert(BufferIsValid(buffer));
@@ -633,6 +670,9 @@ ginRedoDeleteListPages(XLogRecPtr lsn, XLogRecord *record)
633670
Pagemetapage;
634671
inti;
635672

673+
/* Backup blocks are not used in delete_listpage records */
674+
Assert(!(record->xl_info&XLR_BKP_BLOCK_MASK));
675+
636676
metabuffer=XLogReadBuffer(data->node,GIN_METAPAGE_BLKNO, false);
637677
if (!BufferIsValid(metabuffer))
638678
return;/* assume index was deleted, nothing to do */
@@ -646,6 +686,16 @@ ginRedoDeleteListPages(XLogRecPtr lsn, XLogRecord *record)
646686
MarkBufferDirty(metabuffer);
647687
}
648688

689+
/*
690+
* In normal operation, shiftList() takes exclusive lock on all the
691+
* pages-to-be-deleted simultaneously.During replay, however, it should
692+
* be all right to lock them one at a time. This is dependent on the fact
693+
* that we are deleting pages from the head of the list, and that readers
694+
* share-lock the next page before releasing the one they are on. So we
695+
* cannot get past a reader that is on, or due to visit, any page we are
696+
* going to delete. New incoming readers will block behind our metapage
697+
* lock and then see a fully updated page list.
698+
*/
649699
for (i=0;i<data->ndeleted;i++)
650700
{
651701
Bufferbuffer=XLogReadBuffer(data->node,data->toDelete[i], false);
@@ -678,8 +728,6 @@ gin_redo(XLogRecPtr lsn, XLogRecord *record)
678728
* GIN indexes do not require any conflict processing.
679729
*/
680730

681-
RestoreBkpBlocks(lsn,record, false);
682-
683731
topCtx=MemoryContextSwitchTo(opCtx);
684732
switch (info)
685733
{

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp