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Adjust WAL code so that checkpoints truncate the xlog at the previous
checkpoint's redo pointer, not its undo pointer, per discussion in pghackers a few days ago. No point in hanging onto undo information until we have the ability to do something with it --- and this solves a rather large problem with log space for long-running transactions. Also, change all calls of write() to detect the case where write returned a count less than requested, but failed to set errno. Presume that this situation indicates ENOSPC, and give the appropriate error message, rather than a random message associated with the previous value of errno.
1 parent ce370ee commit 1173344

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6 files changed

+76
-20
lines changed

6 files changed

+76
-20
lines changed

‎contrib/dbase/dbf.c

Lines changed: 5 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -155,9 +155,8 @@ int dbf_write_head(dbhead *dbh) {
155155
put_short(head.dbh_hlen, dbh->db_hlen);
156156
put_short(head.dbh_rlen, dbh->db_rlen);
157157

158-
if (write(dbh->db_fd, &head, sizeof(dbf_header)) == -1 ) {
158+
if (write(dbh->db_fd, &head, sizeof(dbf_header)) != sizeof(dbf_header))
159159
return DBF_ERROR;
160-
}
161160

162161
return 0;
163162
}
@@ -180,14 +179,12 @@ int dbf_put_fields(dbhead *dbh) {
180179
field.dbf_flen = dbh->db_fields[t].db_flen;
181180
field.dbf_dec = dbh->db_fields[t].db_dec;
182181

183-
if (write(dbh->db_fd, &field, sizeof(dbf_field)) == -1) {
182+
if (write(dbh->db_fd, &field, sizeof(dbf_field)) != sizeof(dbf_field))
184183
return DBF_ERROR;
185-
}
186184
}
187185

188-
if (write(dbh->db_fd, &end, 1) == -1) {
186+
if (write(dbh->db_fd, &end, 1) != 1)
189187
return DBF_ERROR;
190-
}
191188

192189
return 0;
193190
}
@@ -457,15 +454,13 @@ int dbf_put_record(dbhead *dbh, field *rec, u_long where) {
457454
idx += rec[t].db_flen;
458455
}
459456

460-
if (write(dbh->db_fd, data, dbh->db_rlen) == -1) {
457+
if (write(dbh->db_fd, data, dbh->db_rlen) != dbh->db_rlen)
461458
return DBF_ERROR;
462-
}
463459

464460
/* There's a 0x1A at the end of a dbf-file */
465461
if (where == dbh->db_records) {
466-
if (write(dbh->db_fd, &end, 1) == -1) {
462+
if (write(dbh->db_fd, &end, 1) != 1)
467463
return DBF_ERROR;
468-
}
469464
}
470465

471466
dbh->db_offset += dbh->db_rlen;

‎contrib/pg_resetxlog/pg_resetxlog.c

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@
2323
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
2424
* Portions Copyright (c) 1994, Regents of the University of California
2525
*
26-
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.4 2001/05/30 14:18:18 momjian Exp $
26+
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.5 2001/06/06 17:07:38 tgl Exp $
2727
*
2828
*-------------------------------------------------------------------------
2929
*/
@@ -772,8 +772,12 @@ RewriteControlFile(void)
772772
exit(1);
773773
}
774774

775+
errno = 0;
775776
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
776777
{
778+
/* if write didn't set errno, assume problem is no disk space */
779+
if (errno == 0)
780+
errno = ENOSPC;
777781
perror("RewriteControlFile failed to write pg_control file");
778782
exit(1);
779783
}
@@ -884,8 +888,12 @@ WriteEmptyXLOG(void)
884888
exit(1);
885889
}
886890

891+
errno = 0;
887892
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
888893
{
894+
/* if write didn't set errno, assume problem is no disk space */
895+
if (errno == 0)
896+
errno = ENOSPC;
889897
perror("WriteEmptyXLOG: failed to write xlog file");
890898
exit(1);
891899
}
@@ -894,8 +902,11 @@ WriteEmptyXLOG(void)
894902
memset(buffer, 0, BLCKSZ);
895903
for (nbytes = BLCKSZ; nbytes < XLogSegSize; nbytes += BLCKSZ)
896904
{
905+
errno = 0;
897906
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
898907
{
908+
if (errno == 0)
909+
errno = ENOSPC;
899910
perror("WriteEmptyXLOG: failed to write xlog file");
900911
exit(1);
901912
}

‎src/backend/access/transam/xlog.c

Lines changed: 38 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.68 2001/06/03 14:53:56 petere Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.69 2001/06/06 17:07:38 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -1068,9 +1068,15 @@ XLogWrite(XLogwrtRqst WriteRqst)
10681068

10691069
/* OK to write the page */
10701070
from = XLogCtl->pages + Write->curridx * BLCKSZ;
1071+
errno = 0;
10711072
if (write(openLogFile, from, BLCKSZ) != BLCKSZ)
1073+
{
1074+
/* if write didn't set errno, assume problem is no disk space */
1075+
if (errno == 0)
1076+
errno = ENOSPC;
10721077
elog(STOP, "write of log file %u, segment %u, offset %u failed: %m",
10731078
openLogId, openLogSeg, openLogOff);
1079+
}
10741080
openLogOff += BLCKSZ;
10751081

10761082
/*
@@ -1323,6 +1329,7 @@ XLogFileInit(uint32 log, uint32 seg,
13231329
MemSet(zbuffer, 0, sizeof(zbuffer));
13241330
for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(zbuffer))
13251331
{
1332+
errno = 0;
13261333
if ((int) write(fd, zbuffer, sizeof(zbuffer)) != (int) sizeof(zbuffer))
13271334
{
13281335
int save_errno = errno;
@@ -1332,7 +1339,8 @@ XLogFileInit(uint32 log, uint32 seg,
13321339
* space
13331340
*/
13341341
unlink(tmppath);
1335-
errno = save_errno;
1342+
/* if write didn't set errno, assume problem is no disk space */
1343+
errno = save_errno ? save_errno : ENOSPC;
13361344

13371345
elog(STOP, "ZeroFill failed to create or write %s: %m", tmppath);
13381346
}
@@ -1990,8 +1998,14 @@ WriteControlFile(void)
19901998
elog(STOP, "WriteControlFile: could not create control file (%s): %m",
19911999
ControlFilePath);
19922000

2001+
errno = 0;
19932002
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
2003+
{
2004+
/* if write didn't set errno, assume problem is no disk space */
2005+
if (errno == 0)
2006+
errno = ENOSPC;
19942007
elog(STOP, "WriteControlFile: write to control file failed: %m");
2008+
}
19952009

19962010
if (pg_fsync(fd) != 0)
19972011
elog(STOP, "WriteControlFile: fsync of control file failed: %m");
@@ -2109,8 +2123,14 @@ UpdateControlFile(void)
21092123
if (fd < 0)
21102124
elog(STOP, "could not open control file (%s): %m", ControlFilePath);
21112125

2126+
errno = 0;
21122127
if (write(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData))
2128+
{
2129+
/* if write didn't set errno, assume problem is no disk space */
2130+
if (errno == 0)
2131+
errno = ENOSPC;
21132132
elog(STOP, "write to control file failed: %m");
2133+
}
21142134

21152135
if (pg_fsync(fd) != 0)
21162136
elog(STOP, "fsync of control file failed: %m");
@@ -2248,8 +2268,14 @@ BootStrapXLOG(void)
22482268
use_existent = false;
22492269
openLogFile = XLogFileInit(0, 0, &use_existent, false);
22502270

2271+
errno = 0;
22512272
if (write(openLogFile, buffer, BLCKSZ) != BLCKSZ)
2273+
{
2274+
/* if write didn't set errno, assume problem is no disk space */
2275+
if (errno == 0)
2276+
errno = ENOSPC;
22522277
elog(STOP, "BootStrapXLOG failed to write log file: %m");
2278+
}
22532279

22542280
if (pg_fsync(openLogFile) != 0)
22552281
elog(STOP, "BootStrapXLOG failed to fsync log file: %m");
@@ -2852,15 +2878,22 @@ CreateCheckPoint(bool shutdown)
28522878
elog(STOP, "concurrent transaction log activity while database system is shutting down");
28532879

28542880
/*
2855-
* Remember location of prior checkpoint's earliest info. Oldest item
2856-
* is redo or undo, whichever is older; but watch out for case that
2857-
* undo = 0.
2881+
* Select point at which we can truncate the log, which we base on the
2882+
* prior checkpoint's earliest info.
2883+
*
2884+
* With UNDO support: oldest item is redo or undo, whichever is older;
2885+
* but watch out for case that undo = 0.
2886+
*
2887+
* Without UNDO support: just use the redo pointer. This allows xlog
2888+
* space to be freed much faster when there are long-running transactions.
28582889
*/
2890+
#ifdef NOT_USED
28592891
if (ControlFile->checkPointCopy.undo.xrecoff != 0 &&
28602892
XLByteLT(ControlFile->checkPointCopy.undo,
28612893
ControlFile->checkPointCopy.redo))
28622894
XLByteToSeg(ControlFile->checkPointCopy.undo, _logId, _logSeg);
28632895
else
2896+
#endif
28642897
XLByteToSeg(ControlFile->checkPointCopy.redo, _logId, _logSeg);
28652898

28662899
/*

‎src/backend/storage/file/fd.c

Lines changed: 8 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.79 2001/05/30 14:15:26 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.80 2001/06/06 17:07:46 tgl Exp $
1111
*
1212
* NOTES:
1313
*
@@ -865,7 +865,14 @@ FileWrite(File file, char *buffer, int amount)
865865
VfdCache[file].seekPos, amount, buffer));
866866

867867
FileAccess(file);
868+
869+
errno = 0;
868870
returnCode = write(VfdCache[file].fd, buffer, amount);
871+
872+
/* if write didn't set errno, assume problem is no disk space */
873+
if (returnCode != amount && errno == 0)
874+
errno = ENOSPC;
875+
869876
if (returnCode > 0)
870877
VfdCache[file].seekPos += returnCode;
871878
else

‎src/backend/storage/smgr/md.c

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.84 2001/05/10 20:38:49 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.85 2001/06/06 17:07:46 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -582,8 +582,12 @@ mdblindwrt(RelFileNode rnode,
582582
status = SM_SUCCESS;
583583

584584
/* write and optionally sync the block */
585+
errno = 0;
585586
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
586587
{
588+
/* if write didn't set errno, assume problem is no disk space */
589+
if (errno == 0)
590+
errno = ENOSPC;
587591
elog(DEBUG, "mdblindwrt: write() failed: %m");
588592
status = SM_FAIL;
589593
}

‎src/backend/utils/init/miscinit.c

Lines changed: 8 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.68 2001/06/01 20:27:41 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.69 2001/06/06 17:07:46 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -659,13 +659,15 @@ CreateLockFile(const char *filename, bool amPostmaster,
659659
snprintf(buffer, sizeof(buffer), "%d\n%s\n",
660660
amPostmaster ? (int) my_pid : -((int) my_pid),
661661
DataDir);
662+
errno = 0;
662663
if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
663664
{
664665
int save_errno = errno;
665666

666667
close(fd);
667668
unlink(filename);
668-
errno = save_errno;
669+
/* if write didn't set errno, assume problem is no disk space */
670+
errno = save_errno ? save_errno : ENOSPC;
669671
elog(FATAL, "Can't write lock file %s: %m", filename);
670672
}
671673
close(fd);
@@ -794,9 +796,13 @@ RecordSharedMemoryInLockFile(IpcMemoryKey shmKey, IpcMemoryId shmId)
794796
* update should appear atomic to onlookers.
795797
*/
796798
len = strlen(buffer);
799+
errno = 0;
797800
if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
798801
(int) write(fd, buffer, len) != len)
799802
{
803+
/* if write didn't set errno, assume problem is no disk space */
804+
if (errno == 0)
805+
errno = ENOSPC;
800806
elog(DEBUG, "Failed to write %s: %m", directoryLockFile);
801807
close(fd);
802808
return;

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