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<!--
doc/src/sgml/ref/pg_waldump.sgml
PostgreSQL documentation
-->
<refentry id="pgwaldump">
<indexterm zone="pgwaldump">
<primary>pg_waldump</primary>
</indexterm>
<refmeta>
<refentrytitle><application>pg_waldump</application></refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo>Application</refmiscinfo>
</refmeta>
<refnamediv>
<refname>pg_waldump</refname>
<refpurpose>display a human-readable rendering of the write-ahead log of a <productname>PostgreSQL</productname> database cluster</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>pg_waldump</command>
<arg rep="repeat" choice="opt"><option>option</option></arg>
<arg choice="opt"><option>startseg</option>
<arg choice="opt"><option>endseg</option></arg>
</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 id="R1-APP-PGWALDUMP-1">
<title>Description</title>
<para>
<command>pg_waldump</command> displays the write-ahead log (WAL) and is mainly
useful for debugging or educational purposes.
</para>
<para>
This utility can only be run by the user who installed the server, because
it requires read-only access to the data directory.
</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>
The following command-line options control the location and format of the
output:
<variablelist>
<varlistentry>
<term><replaceable class="parameter">startseg</replaceable></term>
<listitem>
<para>
Start reading at the specified log segment file. This implicitly determines
the path in which files will be searched for, and the timeline to use.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">endseg</replaceable></term>
<listitem>
<para>
Stop after reading the specified log segment file.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-b</option></term>
<term><option>--bkp-details</option></term>
<listitem>
<para>
Output detailed information about backup blocks.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-e <replaceable>end</replaceable></option></term>
<term><option>--end=<replaceable>end</replaceable></option></term>
<listitem>
<para>
Stop reading at the specified WAL location, instead of reading to the
end of the log stream.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-f</option></term>
<term><option>--follow</option></term>
<listitem>
<para>
After reaching the end of valid WAL, keep polling once per second for
new WAL to appear.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-n <replaceable>limit</replaceable></option></term>
<term><option>--limit=<replaceable>limit</replaceable></option></term>
<listitem>
<para>
Display the specified number of records, then stop.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-p <replaceable>path</replaceable></option></term>
<term><option>--path=<replaceable>path</replaceable></option></term>
<listitem>
<para>
Specifies a directory to search for log segment files or a
directory with a <literal>pg_wal</literal> subdirectory that
contains such files. The default is to search in the current
directory, the <literal>pg_wal</literal> subdirectory of the
current directory, and the <literal>pg_wal</literal> subdirectory
of <envar>PGDATA</envar>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-r <replaceable>rmgr</replaceable></option></term>
<term><option>--rmgr=<replaceable>rmgr</replaceable></option></term>
<listitem>
<para>
Only display records generated by the specified resource manager.
If <literal>list</> is passed as name, print a list of valid resource manager
names, and exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-s <replaceable>start</replaceable></option></term>
<term><option>--start=<replaceable>start</replaceable></option></term>
<listitem>
<para>
WAL location at which to start reading. The default is to start reading
the first valid log record found in the earliest file found.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t <replaceable>timeline</replaceable></option></term>
<term><option>--timeline=<replaceable>timeline</replaceable></option></term>
<listitem>
<para>
Timeline from which to read log records. The default is to use the
value in <replaceable>startseg</>, if that is specified; otherwise, the
default is 1.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-V</></term>
<term><option>--version</></term>
<listitem>
<para>
Print the <application>pg_waldump</application> version and exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-x <replaceable>xid</replaceable></option></term>
<term><option>--xid=<replaceable>xid</replaceable></option></term>
<listitem>
<para>
Only display records marked with the given transaction ID.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-z</option></term>
<term><option>--stats[=record]</option></term>
<listitem>
<para>
Display summary statistics (number and size of records and
full-page images) instead of individual records. Optionally
generate statistics per-record instead of per-rmgr.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-?</></term>
<term><option>--help</></term>
<listitem>
<para>
Show help about <application>pg_waldump</application> command line
arguments, and exit.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Can give wrong results when the server is running.
</para>
<para>
Only the specified timeline is displayed (or the default, if none is
specified). Records in other timelines are ignored.
</para>
<para>
<application>pg_waldump</> cannot read WAL files with suffix
<literal>.partial</>. If those files need to be read, <literal>.partial</>
suffix needs to be removed from the file name.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="wal-internals"></member>
</simplelist>
</refsect1>
</refentry>
|
