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Add test to WAL replay to verify that xl_prev points back to the previous
WAL record; this is necessary to be sure we recognize stale WAL records when a WAL page was only partially written during a system crash.
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.109.2.4 2004/08/11 04:08:39 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.109.2.5 2005/05/31 19:11:14 tgl Exp $
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*
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*
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*-------------------------------------------------------------------------
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*-------------------------------------------------------------------------
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*/
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*/
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@ -431,8 +431,8 @@ static uint32 readOff = 0;
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static char *readBuf = NULL;
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static char *readBuf = NULL;
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/* State information for XLOG reading */
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/* State information for XLOG reading */
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static XLogRecPtr ReadRecPtr;
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static XLogRecPtr ReadRecPtr; /* start of last record read */
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static XLogRecPtr EndRecPtr;
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static XLogRecPtr EndRecPtr; /* end+1 of last record read */
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static XLogRecord *nextRecord = NULL;
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static XLogRecord *nextRecord = NULL;
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static StartUpID lastReadSUI;
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static StartUpID lastReadSUI;
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@ -1866,6 +1866,37 @@ got_record:;
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RecPtr->xlogid, RecPtr->xrecoff);
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RecPtr->xlogid, RecPtr->xrecoff);
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goto next_record_is_invalid;
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goto next_record_is_invalid;
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}
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}
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if (!nextmode)
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{
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/*
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* We can't exactly verify the prev-link, but surely it should be
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* less than the record's own address.
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*/
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if (!XLByteLT(record->xl_prev, *RecPtr))
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{
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elog(emode,
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"ReadRecord: record with incorrect prev-link %X/%X at %X/%X",
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record->xl_prev.xlogid, record->xl_prev.xrecoff,
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RecPtr->xlogid, RecPtr->xrecoff);
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goto next_record_is_invalid;
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}
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}
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else
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{
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/*
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* Record's prev-link should exactly match our previous location.
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* This check guards against torn WAL pages where a stale but
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* valid-looking WAL record starts on a sector boundary.
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*/
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if (!XLByteEQ(record->xl_prev, ReadRecPtr))
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{
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elog(emode,
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"record with incorrect prev-link %X/%X at %X/%X",
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record->xl_prev.xlogid, record->xl_prev.xrecoff,
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RecPtr->xlogid, RecPtr->xrecoff);
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goto next_record_is_invalid;
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}
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}
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/*
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/*
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* Compute total length of record including any appended backup
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* Compute total length of record including any appended backup
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