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Fix replay of XLOG_HEAP_NEWPAGE WAL records to pay attention to the forknum

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field of the WAL record.  The previous coding always wrote to the main fork,
resulting in data corruption if the page was meant to go into a non-default
fork.

At present, the only operation that can produce such WAL records is
ALTER TABLE/INDEX SET TABLESPACE when executed with archive_mode = on.
Data corruption would be observed on standby slaves, and could occur on the
master as well if a database crash and recovery occurred after committing
the ALTER and before the next checkpoint.  Per report from Gordon Shannon.

Back-patch to 8.4; the problem doesn't exist in earlier branches because
we didn't have a concept of multiple relation forks then.
This commit is contained in:
Tom Lane 2010-05-02 22:28:11 +00:00
parent 3d94d77159
commit 62938d6cc8
1 changed files with 4 additions and 2 deletions
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6
src/backend/access/heap/heapam.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.277.2.1 2009/08/24 02:18:40 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.277.2.2 2010/05/02 22:28:11 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -4195,8 +4195,10 @@ heap_xlog_newpage(XLogRecPtr lsn, XLogRecord *record)
* Note: the NEWPAGE log record is used for both heaps and indexes, so do
* not do anything that assumes we are touching a heap.
*/
buffer = XLogReadBuffer(xlrec->node, xlrec->blkno, true);
buffer = XLogReadBufferExtended(xlrec->node, xlrec->forknum, xlrec->blkno,
RBM_ZERO);
Assert(BufferIsValid(buffer));
LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
page = (Page) BufferGetPage(buffer);
Assert(record->xl_len == SizeOfHeapNewpage + BLCKSZ);