rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

pg_resetwal: Allow users to change the WAL segment size 

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
doc/src/sgml/ref/pg_resetwal.sgml
View File

@ -275,6 +275,28 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>--wal-segsize=<replaceable class="parameter">wal_segment_size</replaceable></option></term>
<listitem>
<para>
Set the new WAL segment size, in megabytes. The value must be set to a
power of 2 between 1 and 1024 (megabytes). See the same option of <xref
linkend="app-initdb"/> for more information.
</para>
<note>
<para>
While <command>pg_resetwal</command> will set the WAL starting address
beyond the latest existing WAL segment file, some segment size changes
can cause previous WAL file names to be reused. It is recommended to
use <option>-l</option> together with this option to manually set the
WAL starting address if WAL file name overlap will cause problems with
your archiving strategy.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-x <replaceable class="parameter">xid</replaceable></option></term>
<term><option>--next-transaction-id=<replaceable class="parameter">xid</replaceable></option></term>

52
src/bin/pg_resetwal/pg_resetwal.c
View File

@ -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"));
}