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31dcfae83c
Referring to the WAL as just "log" invites confusion with the postmaster log, so avoid doing that in docs and error messages. Also shorten "WAL segment file" to just "WAL file" in various places. Bharath Rupireddy, reviewed by Nathan Bossart and Kyotaro Horiguchi Discussion: https://postgr.es/m/CALj2ACUeXa8tDPaiTLexBDMZ7hgvaN+RTb957-cn5qwv9zf-MQ@mail.gmail.com
341 lines
11 KiB
Plaintext
341 lines
11 KiB
Plaintext
<!--
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doc/src/sgml/ref/pg_waldump.sgml
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PostgreSQL documentation
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-->
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<refentry id="pgwaldump">
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<indexterm zone="pgwaldump">
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<primary>pg_waldump</primary>
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</indexterm>
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<refmeta>
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<refentrytitle><application>pg_waldump</application></refentrytitle>
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<manvolnum>1</manvolnum>
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<refmiscinfo>Application</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>pg_waldump</refname>
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<refpurpose>display a human-readable rendering of the write-ahead log of a <productname>PostgreSQL</productname> database cluster</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>pg_waldump</command>
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<arg rep="repeat" choice="opt"><option>option</option></arg>
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<arg choice="opt"><option>startseg</option><arg choice="opt"><option>endseg</option></arg></arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1 id="r1-app-pgwaldump-1">
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<title>Description</title>
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<para>
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<command>pg_waldump</command> displays the write-ahead log (WAL) and is mainly
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useful for debugging or educational purposes.
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</para>
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<para>
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This utility can only be run by the user who installed the server, because
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it requires read-only access to the data directory.
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</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>
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The following command-line options control the location and format of the
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output:
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">startseg</replaceable></term>
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<listitem>
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<para>
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Start reading at the specified WAL segment file. This implicitly determines
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the path in which files will be searched for, and the timeline to use.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">endseg</replaceable></term>
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<listitem>
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<para>
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Stop after reading the specified WAL segment file.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-b</option></term>
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<term><option>--bkp-details</option></term>
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<listitem>
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<para>
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Output detailed information about backup blocks.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-B <replaceable>block</replaceable></option></term>
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<term><option>--block=<replaceable>block</replaceable></option></term>
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<listitem>
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<para>
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Only display records that modify the given block. The relation must
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also be provided with <option>--relation</option> or
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<option>-R</option>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-e <replaceable>end</replaceable></option></term>
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<term><option>--end=<replaceable>end</replaceable></option></term>
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<listitem>
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<para>
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Stop reading at the specified WAL location, instead of reading to the
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end of the log stream.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-f</option></term>
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<term><option>--follow</option></term>
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<listitem>
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<para>
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After reaching the end of valid WAL, keep polling once per second for
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new WAL to appear.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-F <replaceable>fork</replaceable></option></term>
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<term><option>--fork=<replaceable>fork</replaceable></option></term>
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<listitem>
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<para>
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If provided, only display records that modify blocks in the given fork.
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The valid values are <literal>main</literal> for the main fork,
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<literal>fsm</literal> for the free space map,
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<literal>vm</literal> for the visibility map,
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and <literal>init</literal> for the init fork.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-n <replaceable>limit</replaceable></option></term>
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<term><option>--limit=<replaceable>limit</replaceable></option></term>
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<listitem>
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<para>
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Display the specified number of records, then stop.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-p <replaceable>path</replaceable></option></term>
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<term><option>--path=<replaceable>path</replaceable></option></term>
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<listitem>
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<para>
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Specifies a directory to search for WAL segment files or a
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directory with a <literal>pg_wal</literal> subdirectory that
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contains such files. The default is to search in the current
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directory, the <literal>pg_wal</literal> subdirectory of the
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current directory, and the <literal>pg_wal</literal> subdirectory
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of <envar>PGDATA</envar>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-q</option></term>
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<term><option>--quiet</option></term>
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<listitem>
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<para>
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Do not print any output, except for errors. This option can be useful
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when you want to know whether a range of WAL records can be
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successfully parsed but don't care about the record contents.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-r <replaceable>rmgr</replaceable></option></term>
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<term><option>--rmgr=<replaceable>rmgr</replaceable></option></term>
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<listitem>
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<para>
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Only display records generated by the specified resource manager. You can
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specify the option multiple times to select multiple resource managers.
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If <literal>list</literal> is passed as name, print a list of valid resource manager
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names, and exit.
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</para>
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<para>
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Extensions may define custom resource managers, but pg_waldump does
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not load the extension module and therefore does not recognize custom
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resource managers by name. Instead, you can specify the custom
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resource managers as <literal>custom###</literal> where
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"<literal>###</literal>" is the three-digit resource manager ID. Names
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of this form will always be considered valid.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-R <replaceable>tblspc</replaceable>/<replaceable>db</replaceable>/<replaceable>rel</replaceable></option></term>
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<term><option>--relation=<replaceable>tblspc</replaceable>/<replaceable>db</replaceable>/<replaceable>rel</replaceable></option></term>
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<listitem>
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<para>
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Only display records that modify blocks in the given relation. The
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relation is specified with tablespace OID, database OID, and relfilenode
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separated by slashes, for example <literal>1234/12345/12345</literal>.
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This is the same format used for relations in the program's output.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-s <replaceable>start</replaceable></option></term>
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<term><option>--start=<replaceable>start</replaceable></option></term>
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<listitem>
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<para>
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WAL location at which to start reading. The default is to start reading
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the first valid WAL record found in the earliest file found.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-t <replaceable>timeline</replaceable></option></term>
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<term><option>--timeline=<replaceable>timeline</replaceable></option></term>
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<listitem>
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<para>
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Timeline from which to read WAL records. The default is to use the
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value in <replaceable>startseg</replaceable>, if that is specified; otherwise, the
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default is 1.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-V</option></term>
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<term><option>--version</option></term>
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<listitem>
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<para>
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Print the <application>pg_waldump</application> version and exit.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-w</option></term>
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<term><option>--fullpage</option></term>
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<listitem>
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<para>
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Only display records that include full page images.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-x <replaceable>xid</replaceable></option></term>
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<term><option>--xid=<replaceable>xid</replaceable></option></term>
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<listitem>
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<para>
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Only display records marked with the given transaction ID.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-z</option></term>
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<term><option>--stats[=record]</option></term>
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<listitem>
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<para>
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Display summary statistics (number and size of records and
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full-page images) instead of individual records. Optionally
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generate statistics per-record instead of per-rmgr.
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</para>
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<para>
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If <application>pg_waldump</application> is terminated by signal
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<systemitem>SIGINT</systemitem>
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(<keycombo action="simul"><keycap>Control</keycap><keycap>C</keycap></keycombo>),
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the summary of the statistics computed is displayed up to the
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termination point. This operation is not supported on
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<productname>Windows</productname>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-?</option></term>
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<term><option>--help</option></term>
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<listitem>
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<para>
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Show help about <application>pg_waldump</application> command line
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arguments, and exit.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1>
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<title>Environment</title>
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<variablelist>
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<varlistentry>
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<term><envar>PGDATA</envar></term>
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<listitem>
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<para>
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Data directory; see also the <option>-p</option> option.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><envar>PG_COLOR</envar></term>
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<listitem>
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<para>
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Specifies whether to use color in diagnostic messages. Possible values
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are <literal>always</literal>, <literal>auto</literal> and
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<literal>never</literal>.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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Can give wrong results when the server is running.
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</para>
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<para>
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Only the specified timeline is displayed (or the default, if none is
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specified). Records in other timelines are ignored.
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</para>
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<para>
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<application>pg_waldump</application> cannot read WAL files with suffix
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<literal>.partial</literal>. If those files need to be read, <literal>.partial</literal>
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suffix needs to be removed from the file name.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="wal-internals"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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