1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/pg_resetxlog.sgml,v 1.5 2002/08/29 22:19:03 petere Exp $
PostgreSQL documentation
-->
<refentry id="APP-PGRESETXLOG">
<refmeta>
<refentrytitle id="APP-PGRESETXLOG-TITLE"><application>pg_resetxlog</application></refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo>Application</refmiscinfo>
</refmeta>
<refnamediv>
<refname>pg_resetxlog</refname>
<refpurpose>reset write-ahead log file and optionally the pg_control file</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>pg_resetxlog</command>
<arg> -f </arg>
<arg> -n </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>
</cmdsynopsis>
</refsynopsisdiv>
<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
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.
</para>
<para>
After running this command, it should be possible to start the server,
but bear in mind that the database may contain inconsistent data due to
partially-committed transactions. You should immediately dump your data,
run <application>initdb</>, and reload. After reload, check for
inconsistencies and repair as needed.
</para>
<para>
This utility can only be run by the user who installed the server, because
it requires read/write access to the <literal>datadir</>.
For safety reasons, you must specify the data directory on the command line.
<command>pg_resetxlog</command> does not use the environment variable
<envar>PGDATA</>.
</para>
<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
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>-n</> (no operation) switch instructs
<command>pg_resetxlog</command> to print the values reconstructed from
<filename>pg_control</> and then exit without modifying anything.
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>
<title>Notes</title>
<para>
This command must not be used when the <application>postmaster</> is
running. <command>pg_resetxlog</command> will refuse to start up if
it finds a postmaster lock file in the <literal>datadir</>. If the
<application>postmaster</> crashed then a lock file may have been left
behind; in that case you can remove the lock file to allow
<command>pg_resetxlog</command> to run. But before you do
so, make doubly certain that there
is no postmaster nor any backend server process still alive.
</para>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:nil
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
End:
-->
|
