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Commit1b87e24

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Change xlog page-header format to include StartUpID. Use the SUI to
detect case that next page in log came from an older run than the priorpage. This avoids the necessity to re-zero the log after recovery froma crash, which is good because we need not risk destroying valuable loginformation.This forces another initdb since yesterday :-(. Need to get that logreset utility done...
1 parente2f9138 commit1b87e24

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2 files changed

+63
-16
lines changed

2 files changed

+63
-16
lines changed

‎src/backend/access/transam/xlog.c

Lines changed: 54 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -1,12 +1,13 @@
11
/*-------------------------------------------------------------------------
22
*
33
* xlog.c
4+
*PostgreSQL transaction log manager
45
*
56
*
67
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
78
* Portions Copyright (c) 1994, Regents of the University of California
89
*
9-
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.56 2001/03/1301:17:05 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.57 2001/03/1320:32:37 tgl Exp $
1011
*
1112
*-------------------------------------------------------------------------
1213
*/
@@ -344,6 +345,7 @@ static char *readBuf = NULL;
344345
staticXLogRecPtrReadRecPtr;
345346
staticXLogRecPtrEndRecPtr;
346347
staticXLogRecord*nextRecord=NULL;
348+
staticStartUpIDlastReadSUI;
347349

348350
staticboolInRedo= false;
349351

@@ -355,6 +357,7 @@ static intXLogFileOpen(uint32 log, uint32 seg, bool econt);
355357
staticvoidPreallocXlogFiles(XLogRecPtrendptr);
356358
staticvoidMoveOfflineLogs(uint32log,uint32seg);
357359
staticXLogRecord*ReadRecord(XLogRecPtr*RecPtr,intemode,char*buffer);
360+
staticboolValidXLOGHeader(XLogPageHeaderhdr,intemode,boolcheckSUI);
358361
staticXLogRecord*ReadCheckpointRecord(XLogRecPtrRecPtr,
359362
constchar*whichChkpt,
360363
char*buffer);
@@ -891,6 +894,7 @@ AdvanceXLInsertBuffer(void)
891894
MemSet((char*)Insert->currpage,0,BLCKSZ);
892895
Insert->currpage->xlp_magic=XLOG_PAGE_MAGIC;
893896
/* Insert->currpage->xlp_info = 0; *//* done by memset */
897+
Insert->currpage->xlp_sui=ThisStartUpID;
894898

895899
returnupdate_needed;
896900
}
@@ -1498,6 +1502,7 @@ ReadRecord(XLogRecPtr *RecPtr, int emode, char *buffer)
14981502
total_len;
14991503
uint32targetPageOff;
15001504
unsignedi;
1505+
boolnextmode= false;
15011506

15021507
if (readBuf==NULL)
15031508
{
@@ -1516,6 +1521,7 @@ ReadRecord(XLogRecPtr *RecPtr, int emode, char *buffer)
15161521
if (RecPtr==NULL)
15171522
{
15181523
RecPtr=&tmpRecPtr;
1524+
nextmode= true;
15191525
/* fast case if next record is on same page */
15201526
if (nextRecord!=NULL)
15211527
{
@@ -1566,13 +1572,8 @@ ReadRecord(XLogRecPtr *RecPtr, int emode, char *buffer)
15661572
readId,readSeg,readOff);
15671573
gotonext_record_is_invalid;
15681574
}
1569-
if (((XLogPageHeader)readBuf)->xlp_magic!=XLOG_PAGE_MAGIC)
1570-
{
1571-
elog(emode,"ReadRecord: invalid magic number %u in logfile %u seg %u off %u",
1572-
((XLogPageHeader)readBuf)->xlp_magic,
1573-
readId,readSeg,readOff);
1575+
if (!ValidXLOGHeader((XLogPageHeader)readBuf,emode,nextmode))
15741576
gotonext_record_is_invalid;
1575-
}
15761577
}
15771578
if ((((XLogPageHeader)readBuf)->xlp_info&XLP_FIRST_IS_CONTRECORD)&&
15781579
RecPtr->xrecoff %BLCKSZ==SizeOfXLogPHD)
@@ -1651,13 +1652,8 @@ got_record:;
16511652
readId,readSeg,readOff);
16521653
gotonext_record_is_invalid;
16531654
}
1654-
if (((XLogPageHeader)readBuf)->xlp_magic!=XLOG_PAGE_MAGIC)
1655-
{
1656-
elog(emode,"ReadRecord: invalid magic number %u in logfile %u seg %u off %u",
1657-
((XLogPageHeader)readBuf)->xlp_magic,
1658-
readId,readSeg,readOff);
1655+
if (!ValidXLOGHeader((XLogPageHeader)readBuf,emode, true))
16591656
gotonext_record_is_invalid;
1660-
}
16611657
if (!(((XLogPageHeader)readBuf)->xlp_info&XLP_FIRST_IS_CONTRECORD))
16621658
{
16631659
elog(emode,"ReadRecord: there is no ContRecord flag in logfile %u seg %u off %u",
@@ -1719,6 +1715,50 @@ next_record_is_invalid:;
17191715
returnNULL;
17201716
}
17211717

1718+
/*
1719+
* Check whether the xlog header of a page just read in looks valid.
1720+
*
1721+
* This is just a convenience subroutine to avoid duplicated code in
1722+
* ReadRecord. It's not intended for use from anywhere else.
1723+
*/
1724+
staticbool
1725+
ValidXLOGHeader(XLogPageHeaderhdr,intemode,boolcheckSUI)
1726+
{
1727+
if (hdr->xlp_magic!=XLOG_PAGE_MAGIC)
1728+
{
1729+
elog(emode,"ReadRecord: invalid magic number %04X in logfile %u seg %u off %u",
1730+
hdr->xlp_magic,readId,readSeg,readOff);
1731+
return false;
1732+
}
1733+
if ((hdr->xlp_info& ~XLP_ALL_FLAGS)!=0)
1734+
{
1735+
elog(emode,"ReadRecord: invalid info bits %04X in logfile %u seg %u off %u",
1736+
hdr->xlp_info,readId,readSeg,readOff);
1737+
return false;
1738+
}
1739+
/*
1740+
* We disbelieve a SUI less than the previous page's SUI, or more
1741+
* than a few counts greater. In theory as many as 512 shutdown
1742+
* checkpoint records could appear on a 32K-sized xlog page, so
1743+
* that's the most differential there could legitimately be.
1744+
*
1745+
* Note this check can only be applied when we are reading the next page
1746+
* in sequence, so ReadRecord passes a flag indicating whether to check.
1747+
*/
1748+
if (checkSUI)
1749+
{
1750+
if (hdr->xlp_sui<lastReadSUI||
1751+
hdr->xlp_sui>lastReadSUI+512)
1752+
{
1753+
elog(emode,"ReadRecord: out-of-sequence SUI %u (after %u) in logfile %u seg %u off %u",
1754+
hdr->xlp_sui,lastReadSUI,readId,readSeg,readOff);
1755+
return false;
1756+
}
1757+
}
1758+
lastReadSUI=hdr->xlp_sui;
1759+
return true;
1760+
}
1761+
17221762
/*
17231763
* I/O routines for pg_control
17241764
*
@@ -2023,6 +2063,7 @@ BootStrapXLOG(void)
20232063
memset(buffer,0,BLCKSZ);
20242064
page->xlp_magic=XLOG_PAGE_MAGIC;
20252065
page->xlp_info=0;
2066+
page->xlp_sui=checkPoint.ThisStartUpID;
20262067
record= (XLogRecord*) ((char*)page+SizeOfXLogPHD);
20272068
record->xl_prev.xlogid=0;
20282069
record->xl_prev.xrecoff=0;

‎src/include/access/xlog.h

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: xlog.h,v 1.19 2001/03/1301:17:06 tgl Exp $
9+
* $Id: xlog.h,v 1.20 2001/03/1320:32:37 tgl Exp $
1010
*/
1111
#ifndefXLOG_H
1212
#defineXLOG_H
@@ -26,6 +26,9 @@
2626
* really:
2727
*
2828
* SizeOfXLogRecord + xl_len + n_backup_blocks * (sizeof(BkpBlock) + BLCKSZ)
29+
*
30+
* rounded up to a MAXALIGN boundary (so that all xlog records start on
31+
* MAXALIGN boundaries).
2932
*/
3033
typedefstructXLogRecord
3134
{
@@ -105,12 +108,13 @@ typedef struct XLogContRecord
105108
/*
106109
* Each page of XLOG file has a header like this:
107110
*/
108-
#defineXLOG_PAGE_MAGIC0x17345169/* can be used as WAL version indicator */
111+
#defineXLOG_PAGE_MAGIC0xD058/* can be used as WAL version indicator */
109112

110113
typedefstructXLogPageHeaderData
111114
{
112-
uint32xlp_magic;/* magic value for correctness checks */
115+
uint16xlp_magic;/* magic value for correctness checks */
113116
uint16xlp_info;/* flag bits, see below */
117+
StartUpIDxlp_sui;/* StartUpID of first record on page */
114118
}XLogPageHeaderData;
115119

116120
#defineSizeOfXLogPHDMAXALIGN(sizeof(XLogPageHeaderData))
@@ -119,6 +123,8 @@ typedef XLogPageHeaderData *XLogPageHeader;
119123

120124
/* When record crosses page boundary, set this flag in new page's header */
121125
#defineXLP_FIRST_IS_CONTRECORD0x0001
126+
/* All defined flag bits in xlp_info (used for validity checking of header) */
127+
#defineXLP_ALL_FLAGS0x0001
122128

123129
/*
124130
* We break each logical log file (xlogid value) into 16Mb segments.

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