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Adjust WAL code so that checkpoints truncate the xlog at the previous

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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.
REL7_2_STABLE
Tom Lane 25 years ago
parent ce370eec35
commit 1173344e74
6 changed files with 76 additions and 20 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 15
      contrib/dbase/dbf.c
  2. 13
      contrib/pg_resetxlog/pg_resetxlog.c
  3. 43
      src/backend/access/transam/xlog.c
  4. 9
      src/backend/storage/file/fd.c
  5. 6
      src/backend/storage/smgr/md.c
  6. 10
      src/backend/utils/init/miscinit.c

15
contrib/dbase/dbf.c
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@ -155,9 +155,8 @@ int dbf_write_head(dbhead *dbh) {
put_short(head.dbh_hlen, dbh->db_hlen);
put_short(head.dbh_rlen, dbh->db_rlen);
if (write(dbh->db_fd, &head, sizeof(dbf_header)) == -1 ) {
if (write(dbh->db_fd, &head, sizeof(dbf_header)) != sizeof(dbf_header))
return DBF_ERROR;
}
return 0;
}
@ -180,14 +179,12 @@ int dbf_put_fields(dbhead *dbh) {
field.dbf_flen = dbh->db_fields[t].db_flen;
field.dbf_dec = dbh->db_fields[t].db_dec;
if (write(dbh->db_fd, &field, sizeof(dbf_field)) == -1) {
if (write(dbh->db_fd, &field, sizeof(dbf_field)) != sizeof(dbf_field))
return DBF_ERROR;
}
}
if (write(dbh->db_fd, &end, 1) == -1) {
if (write(dbh->db_fd, &end, 1) != 1)
return DBF_ERROR;
}
return 0;
}
@ -457,16 +454,14 @@ int dbf_put_record(dbhead *dbh, field *rec, u_long where) {
idx += rec[t].db_flen;
}
if (write(dbh->db_fd, data, dbh->db_rlen) == -1) {
if (write(dbh->db_fd, data, dbh->db_rlen) != dbh->db_rlen)
return DBF_ERROR;
}
/* There's a 0x1A at the end of a dbf-file */
if (where == dbh->db_records) {
if (write(dbh->db_fd, &end, 1) == -1) {
if (write(dbh->db_fd, &end, 1) != 1)
return DBF_ERROR;
}
}
dbh->db_offset += dbh->db_rlen;

13
contrib/pg_resetxlog/pg_resetxlog.c
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@ -23,7 +23,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.4 2001/05/30 14:18:18 momjian Exp $
* $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.5 2001/06/06 17:07:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -772,8 +772,12 @@ RewriteControlFile(void)
exit(1);
}
errno = 0;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
perror("RewriteControlFile failed to write pg_control file");
exit(1);
}
@ -884,8 +888,12 @@ WriteEmptyXLOG(void)
exit(1);
}
errno = 0;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
perror("WriteEmptyXLOG: failed to write xlog file");
exit(1);
}
@ -894,8 +902,11 @@ WriteEmptyXLOG(void)
memset(buffer, 0, BLCKSZ);
for (nbytes = BLCKSZ; nbytes < XLogSegSize; nbytes += BLCKSZ)
{
errno = 0;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
if (errno == 0)
errno = ENOSPC;
perror("WriteEmptyXLOG: failed to write xlog file");
exit(1);
}

43
src/backend/access/transam/xlog.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.68 2001/06/03 14:53:56 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.69 2001/06/06 17:07:38 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1068,9 +1068,15 @@ XLogWrite(XLogwrtRqst WriteRqst)
/* OK to write the page */
from = XLogCtl->pages + Write->curridx * BLCKSZ;
errno = 0;
if (write(openLogFile, from, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(STOP, "write of log file %u, segment %u, offset %u failed: %m",
openLogId, openLogSeg, openLogOff);
}
openLogOff += BLCKSZ;
/*
@ -1323,6 +1329,7 @@ XLogFileInit(uint32 log, uint32 seg,
MemSet(zbuffer, 0, sizeof(zbuffer));
for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(zbuffer))
{
errno = 0;
if ((int) write(fd, zbuffer, sizeof(zbuffer)) != (int) sizeof(zbuffer))
{
int save_errno = errno;
@ -1332,7 +1339,8 @@ XLogFileInit(uint32 log, uint32 seg,
* space
*/
unlink(tmppath);
errno = save_errno;
/* if write didn't set errno, assume problem is no disk space */
errno = save_errno ? save_errno : ENOSPC;
elog(STOP, "ZeroFill failed to create or write %s: %m", tmppath);
}
@ -1990,8 +1998,14 @@ WriteControlFile(void)
elog(STOP, "WriteControlFile: could not create control file (%s): %m",
ControlFilePath);
errno = 0;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(STOP, "WriteControlFile: write to control file failed: %m");
}
if (pg_fsync(fd) != 0)
elog(STOP, "WriteControlFile: fsync of control file failed: %m");
@ -2109,8 +2123,14 @@ UpdateControlFile(void)
if (fd < 0)
elog(STOP, "could not open control file (%s): %m", ControlFilePath);
errno = 0;
if (write(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData))
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(STOP, "write to control file failed: %m");
}
if (pg_fsync(fd) != 0)
elog(STOP, "fsync of control file failed: %m");
@ -2248,8 +2268,14 @@ BootStrapXLOG(void)
use_existent = false;
openLogFile = XLogFileInit(0, 0, &use_existent, false);
errno = 0;
if (write(openLogFile, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(STOP, "BootStrapXLOG failed to write log file: %m");
}
if (pg_fsync(openLogFile) != 0)
elog(STOP, "BootStrapXLOG failed to fsync log file: %m");
@ -2852,15 +2878,22 @@ CreateCheckPoint(bool shutdown)
elog(STOP, "concurrent transaction log activity while database system is shutting down");
/*
* Remember location of prior checkpoint's earliest info. Oldest item
* is redo or undo, whichever is older; but watch out for case that
* undo = 0.
* Select point at which we can truncate the log, which we base on the
* prior checkpoint's earliest info.
*
* With UNDO support: oldest item is redo or undo, whichever is older;
* but watch out for case that undo = 0.
*
* Without UNDO support: just use the redo pointer. This allows xlog
* space to be freed much faster when there are long-running transactions.
*/
#ifdef NOT_USED
if (ControlFile->checkPointCopy.undo.xrecoff != 0 &&
XLByteLT(ControlFile->checkPointCopy.undo,
ControlFile->checkPointCopy.redo))
XLByteToSeg(ControlFile->checkPointCopy.undo, _logId, _logSeg);
else
#endif
XLByteToSeg(ControlFile->checkPointCopy.redo, _logId, _logSeg);
/*

9
src/backend/storage/file/fd.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.79 2001/05/30 14:15:26 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/file/fd.c,v 1.80 2001/06/06 17:07:46 tgl Exp $
*
* NOTES:
*
@ -865,7 +865,14 @@ FileWrite(File file, char *buffer, int amount)
VfdCache[file].seekPos, amount, buffer));
FileAccess(file);
errno = 0;
returnCode = write(VfdCache[file].fd, buffer, amount);
/* if write didn't set errno, assume problem is no disk space */
if (returnCode != amount && errno == 0)
errno = ENOSPC;
if (returnCode > 0)
VfdCache[file].seekPos += returnCode;
else

6
src/backend/storage/smgr/md.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.84 2001/05/10 20:38:49 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/smgr/md.c,v 1.85 2001/06/06 17:07:46 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -582,8 +582,12 @@ mdblindwrt(RelFileNode rnode,
status = SM_SUCCESS;
/* write and optionally sync the block */
errno = 0;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(DEBUG, "mdblindwrt: write() failed: %m");
status = SM_FAIL;
}

10
src/backend/utils/init/miscinit.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.68 2001/06/01 20:27:41 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.69 2001/06/06 17:07:46 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -659,13 +659,15 @@ CreateLockFile(const char *filename, bool amPostmaster,
snprintf(buffer, sizeof(buffer), "%d\n%s\n",
amPostmaster ? (int) my_pid : -((int) my_pid),
DataDir);
errno = 0;
if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
{
int save_errno = errno;
close(fd);
unlink(filename);
errno = save_errno;
/* if write didn't set errno, assume problem is no disk space */
errno = save_errno ? save_errno : ENOSPC;
elog(FATAL, "Can't write lock file %s: %m", filename);
}
close(fd);
@ -794,9 +796,13 @@ RecordSharedMemoryInLockFile(IpcMemoryKey shmKey, IpcMemoryId shmId)
* update should appear atomic to onlookers.
*/
len = strlen(buffer);
errno = 0;
if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
(int) write(fd, buffer, len) != len)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
elog(DEBUG, "Failed to write %s: %m", directoryLockFile);
close(fd);
return;

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