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Re-enable pg_resetxlog to accept -l values in hexadecimal (it used to

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be able to do that, but the ability seems to have got lost in the
shuffle).  Add a -o nextOID switch for completeness.  Improve the
documentation to explain how and why to use these switches.
REL7_3_STABLE
Tom Lane 23 years ago
parent 388ad64dc7
commit 71e74a2f58
2 changed files with 94 additions and 28 deletions
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  1. 51
      doc/src/sgml/ref/pg_resetxlog.sgml
  2. 71
      src/bin/pg_resetxlog/pg_resetxlog.c

51
doc/src/sgml/ref/pg_resetxlog.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v 1.5 2002/08/29 22:19:03 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v 1.6 2002/10/02 21:30:13 tgl Exp $
PostgreSQL documentation
-->
@ -12,7 +12,7 @@ PostgreSQL documentation
<refnamediv>
<refname>pg_resetxlog</refname>
<refpurpose>reset write-ahead log file and optionally the pg_control file</refpurpose>
<refpurpose>reset write-ahead log and pg_control contents</refpurpose>
</refnamediv>
<refsynopsisdiv>
@ -20,6 +20,7 @@ PostgreSQL documentation
<command>pg_resetxlog</command>
<arg> -f </arg>
<arg> -n </arg>
<arg> -o <replaceable class="parameter">oid</replaceable> </arg>
<arg> -x <replaceable class="parameter">xid</replaceable> </arg>
<arg> -l <replaceable class="parameter">fileid</replaceable>,<replaceable class="parameter">seg</replaceable> </arg>
<arg choice="plain"><replaceable>datadir</replaceable></arg>
@ -29,8 +30,9 @@ PostgreSQL documentation
<refsect1 id="R1-APP-PGRESETXLOG-1">
<title>Description</title>
<para>
<command>pg_resetxlog</command> clears the write-ahead log file and
optionally the <filename>pg_control</> file. This function is sometimes
<command>pg_resetxlog</command> clears the write-ahead log and
optionally resets some fields in the <filename>pg_control</> file. This
function is sometimes
needed if these files have become corrupted.
It should be used only as a last resort,
when the server will not start due to such corruption.
@ -55,14 +57,45 @@ PostgreSQL documentation
<para>
If <command>pg_resetxlog</command> complains that it cannot determine
valid data for <filename>pg_control</>, you can force it to proceed anyway
by specifying the <literal>-f</> (force) switch. In this case plausible values
will be substituted for the missing data. If <literal>-f</> is used then
by specifying the <literal>-f</> (force) switch. In this case plausible
values will be substituted for the missing data. Most of the fields can be
expected to match, but manual assistance may be needed for the next OID,
next transaction ID, WAL starting address, and database locale fields.
The first three of these can be set using the switches discussed below.
<command>pg_resetxlog</command>'s own environment is the source for its
guess at the locale fields; take care that <envar>LANG</> and so forth
match the environment that <application>initdb</> was run in.
If you are not able to determine correct values for all these fields,
<literal>-f</> can still be used, but
the recovered database must be treated with even more suspicion than
usual --- an immediate dump and reload is imperative. <emphasis>Do not</>
execute any data-modifying operations in the database before you dump,
as any such action is likely to make the corruption worse.
</para>
<para>
The <literal>-o</>, <literal>-x</>, and <literal>-l</> switches allow
the next OID, next transaction ID, and WAL starting address values to
be set manually. These are only needed when
<command>pg_resetxlog</command> is unable to determine appropriate values
by reading <filename>pg_control</>. A safe value for the
next transaction ID may be determined by looking for the largest
file name in <envar>$PGDATA</><filename>/pg_clog</>, adding one,
and then multiplying by 1048576. Note that the file names are in
hexadecimal. It is usually easiest to specify the switch value in
hexadecimal too. For example, if <filename>0011</> is the largest entry
in <filename>pg_clog</>, <literal>-x 0x1200000</> will work (five trailing
zeroes provide the proper multiplier).
The WAL starting address should be
larger than any file number currently existing in
<envar>$PGDATA</><filename>/pg_xlog</>. These also are in hex, and
have two parts. For example, if <filename>000000FF0000003A</> is the
largest entry in <filename>pg_xlog</>, <literal>-l 0xFF,0x3B</> will work.
There is no comparably easy way to determine a next OID that's beyond
the largest one in the database, but fortunately it is not critical to
get the next-OID setting right.
</para>
<para>
The <literal>-n</> (no operation) switch instructs
<command>pg_resetxlog</command> to print the values reconstructed from
@ -70,12 +103,6 @@ PostgreSQL documentation
This is mainly a debugging tool, but may be useful as a sanity check
before allowing <command>pg_resetxlog</command> to proceed for real.
</para>
<para>
The <literal>-x</> and <literal>-l</> switches are intended for use by
<application>pg_upgrade</>. In most cases they should not be used in
manual recovery operations.
</para>
</refsect1>
<refsect1>

71
src/bin/pg_resetxlog/pg_resetxlog.c
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@ -23,7 +23,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.6 2002/10/02 19:45:47 tgl Exp $
* $Header: /cvsroot/pgsql/src/bin/pg_resetxlog/pg_resetxlog.c,v 1.7 2002/10/02 21:30:13 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -90,8 +90,11 @@ main(int argc, char *argv[])
bool force = false;
bool noupdate = false;
TransactionId set_xid = 0;
Oid set_oid = 0;
uint32 minXlogId = 0,
minXlogSeg = 0;
char *endptr;
char *endptr2;
char *DataDir;
int fd;
char path[MAXPGPATH];
@ -122,7 +125,7 @@ main(int argc, char *argv[])
}
while ((c = getopt(argc, argv, "fl:nx:")) != -1)
while ((c = getopt(argc, argv, "fl:no:x:")) != -1)
{
switch (c)
{
@ -135,7 +138,13 @@ main(int argc, char *argv[])
break;
case 'x':
set_xid = strtoul(optarg, NULL, 0);
set_xid = strtoul(optarg, &endptr, 0);
if (endptr == optarg || *endptr != '\0')
{
fprintf(stderr, _("%s: invalid argument for -x option\n"), progname);
fprintf(stderr, _("Try '%s --help' for more information.\n"), progname);
exit(1);
}
if (set_xid == 0)
{
fprintf(stderr, _("%s: transaction ID (-x) must not be 0\n"), progname);
@ -143,8 +152,31 @@ main(int argc, char *argv[])
}
break;
case 'o':
set_oid = strtoul(optarg, &endptr, 0);
if (endptr == optarg || *endptr != '\0')
{
fprintf(stderr, _("%s: invalid argument for -o option\n"), progname);
fprintf(stderr, _("Try '%s --help' for more information.\n"), progname);
exit(1);
}
if (set_oid == 0)
{
fprintf(stderr, _("%s: OID (-o) must not be 0\n"), progname);
exit(1);
}
break;
case 'l':
if (sscanf(optarg, "%u,%u", &minXlogId, &minXlogSeg) != 2)
minXlogId = strtoul(optarg, &endptr, 0);
if (endptr == optarg || *endptr != ',')
{
fprintf(stderr, _("%s: invalid argument for -l option\n"), progname);
fprintf(stderr, _("Try '%s --help' for more information.\n"), progname);
exit(1);
}
minXlogSeg = strtoul(endptr+1, &endptr2, 0);
if (endptr2 == endptr+1 || *endptr2 != '\0')
{
fprintf(stderr, _("%s: invalid argument for -l option\n"), progname);
fprintf(stderr, _("Try '%s --help' for more information.\n"), progname);
@ -198,6 +230,24 @@ main(int argc, char *argv[])
if (!ReadControlFile())
GuessControlValues();
/*
* Adjust fields if required by switches. (Do this now so that
* printout, if any, includes these values.)
*/
if (set_xid != 0)
ControlFile.checkPointCopy.nextXid = set_xid;
if (set_oid != 0)
ControlFile.checkPointCopy.nextOid = set_oid;
if (minXlogId > ControlFile.logId ||
(minXlogId == ControlFile.logId &&
minXlogSeg > ControlFile.logSeg))
{
ControlFile.logId = minXlogId;
ControlFile.logSeg = minXlogSeg;
}
/*
* If we had to guess anything, and -f was not given, just print the
* guessed values and exit. Also print if -n is given.
@ -227,19 +277,7 @@ main(int argc, char *argv[])
/*
* Else, do the dirty deed.
*
* First adjust fields if required by switches.
*/
if (set_xid != 0)
ControlFile.checkPointCopy.nextXid = set_xid;
if (minXlogId > ControlFile.logId ||
(minXlogId == ControlFile.logId && minXlogSeg > ControlFile.logSeg))
{
ControlFile.logId = minXlogId;
ControlFile.logSeg = minXlogSeg;
}
RewriteControlFile();
KillExistingXLOG();
WriteEmptyXLOG();
@ -659,6 +697,7 @@ usage(void)
printf(_(" -f force update to be done\n"));
printf(_(" -l FILEID,SEG force minimum WAL starting location for new transaction log\n"));
printf(_(" -n no update, just show extracted control values (for testing)\n"));
printf(_(" -o OID set next OID\n"));
printf(_(" -x XID set next transaction ID\n"));
printf(_("\nReport bugs to <pgsql-bugs@postgresql.org>.\n"));
}

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