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pg_resetwal: Allow users to change the WAL segment size

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This adds a new option --wal-segsize (analogous to initdb) that changes
the WAL segment size in pg_control.

Author: Nathan Bossart <bossartn@amazon.com>
This commit is contained in:
Peter Eisentraut
2018-03-25 14:58:49 -04:00
parent 8ad8d916f9
commit bf4a8676c3
2 changed files with 65 additions and 9 deletions
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52
src/bin/pg_resetwal/pg_resetwal.c
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@ -72,6 +72,7 @@ static MultiXactOffset set_mxoff = (MultiXactOffset) -1;
static uint32 minXlogTli = 0;
static XLogSegNo minXlogSegNo = 0;
static int WalSegSz;
static int set_wal_segsize;
static void CheckDataVersion(void);
static bool ReadControlFile(void);
@ -100,6 +101,7 @@ main(int argc, char *argv[])
{"next-oid", required_argument, NULL, 'o'},
{"multixact-offset", required_argument, NULL, 'O'},
{"next-transaction-id", required_argument, NULL, 'x'},
{"wal-segsize", required_argument, NULL, 1},
{NULL, 0, NULL, 0}
};
@ -290,6 +292,24 @@ main(int argc, char *argv[])
log_fname = pg_strdup(optarg);
break;
case 1:
set_wal_segsize = strtol(optarg, &endptr, 10) * 1024 * 1024;
if (endptr == optarg || *endptr != '\0')
{
fprintf(stderr,
_("%s: argument of --wal-segsize must be a number\n"),
progname);
exit(1);
}
if (!IsValidWalSegSize(set_wal_segsize))
{
fprintf(stderr,
_("%s: argument of --wal-segsize must be a power of 2 between 1 and 1024\n"),
progname);
exit(1);
}
break;
default:
fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
exit(1);
@ -372,6 +392,14 @@ main(int argc, char *argv[])
if (!ReadControlFile())
GuessControlValues();
/*
* If no new WAL segment size was specified, use the control file value.
*/
if (set_wal_segsize != 0)
WalSegSz = set_wal_segsize;
else
WalSegSz = ControlFile.xlog_seg_size;
if (log_fname != NULL)
XLogFromFileName(log_fname, &minXlogTli, &minXlogSegNo, WalSegSz);
@ -438,6 +466,9 @@ main(int argc, char *argv[])
ControlFile.checkPointCopy.PrevTimeLineID = minXlogTli;
}
if (set_wal_segsize != 0)
ControlFile.xlog_seg_size = WalSegSz;
if (minXlogSegNo > newXlogSegNo)
newXlogSegNo = minXlogSegNo;
@ -608,14 +639,13 @@ ReadControlFile(void)
}
memcpy(&ControlFile, buffer, sizeof(ControlFile));
WalSegSz = ControlFile.xlog_seg_size;
/* return false if WalSegSz is not valid */
if (!IsValidWalSegSize(WalSegSz))
/* return false if WAL segment size is not valid */
if (!IsValidWalSegSize(ControlFile.xlog_seg_size))
{
fprintf(stderr,
_("%s: pg_control specifies invalid WAL segment size (%d bytes); proceed with caution \n"),
progname, WalSegSz);
progname, ControlFile.xlog_seg_size);
return false;
}
@ -694,7 +724,7 @@ GuessControlValues(void)
ControlFile.blcksz = BLCKSZ;
ControlFile.relseg_size = RELSEG_SIZE;
ControlFile.xlog_blcksz = XLOG_BLCKSZ;
WalSegSz = ControlFile.xlog_seg_size = DEFAULT_XLOG_SEG_SIZE;
ControlFile.xlog_seg_size = DEFAULT_XLOG_SEG_SIZE;
ControlFile.nameDataLen = NAMEDATALEN;
ControlFile.indexMaxKeys = INDEX_MAX_KEYS;
ControlFile.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE;
@ -859,6 +889,12 @@ PrintNewControlValues(void)
printf(_("newestCommitTsXid: %u\n"),
ControlFile.checkPointCopy.newestCommitTsXid);
}
if (set_wal_segsize != 0)
{
printf(_("Bytes per WAL segment: %u\n"),
ControlFile.xlog_seg_size);
}
}
@ -910,9 +946,6 @@ RewriteControlFile(void)
ControlFile.max_prepared_xacts = 0;
ControlFile.max_locks_per_xact = 64;
/* Now we can force the recorded xlog seg size to the right thing. */
ControlFile.xlog_seg_size = WalSegSz;
/* Contents are protected with a CRC */
INIT_CRC32C(ControlFile.crc);
COMP_CRC32C(ControlFile.crc,
@ -1048,7 +1081,7 @@ FindEndOfXLOG(void)
* are in virgin territory.
*/
xlogbytepos = newXlogSegNo * ControlFile.xlog_seg_size;
newXlogSegNo = (xlogbytepos + WalSegSz - 1) / WalSegSz;
newXlogSegNo = (xlogbytepos + ControlFile.xlog_seg_size - 1) / WalSegSz;
newXlogSegNo++;
}
@ -1279,6 +1312,7 @@ usage(void)
printf(_(" -O, --multixact-offset=OFFSET set next multitransaction offset\n"));
printf(_(" -V, --version output version information, then exit\n"));
printf(_(" -x, --next-transaction-id=XID set next transaction ID\n"));
printf(_(" --wal-segsize=SIZE size of WAL segments, in megabytes\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
}