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+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>pg_waldump</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="pgupgrade.html" title="pg_upgrade" /><link rel="next" href="app-postgres.html" title="postgres" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center"><span class="application">pg_waldump</span></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="pgupgrade.html" title="pg_upgrade">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="reference-server.html" title="PostgreSQL Server Applications">Up</a></td><th width="60%" align="center">PostgreSQL Server Applications</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="app-postgres.html" title="postgres">Next</a></td></tr></table><hr /></div><div class="refentry" id="PGWALDUMP"><div class="titlepage"></div><a id="id-1.9.5.13.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle"><span class="application">pg_waldump</span></span></h2><p>pg_waldump — display a human-readable rendering of the write-ahead log of a <span class="productname">PostgreSQL</span> database cluster</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="cmdsynopsis"><p id="id-1.9.5.13.4.1"><code class="command">pg_waldump</code> [<code class="option">option</code>...] [<code class="option">startseg</code> [<code class="option">endseg</code>]]</p></div></div><div class="refsect1" id="R1-APP-PGWALDUMP-1"><h2>Description</h2><p>
+ <code class="command">pg_waldump</code> displays the write-ahead log (WAL) and is mainly
+ useful for debugging or educational purposes.
+ </p><p>
+ This utility can only be run by the user who installed the server, because
+ it requires read-only access to the data directory.
+ </p></div><div class="refsect1" id="id-1.9.5.13.6"><h2>Options</h2><p>
+ The following command-line options control the location and format of the
+ output:
+
+ </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>startseg</code></em></span></dt><dd><p>
+ 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.
+ </p></dd><dt><span class="term"><em class="replaceable"><code>endseg</code></em></span></dt><dd><p>
+ Stop after reading the specified log segment file.
+ </p></dd><dt><span class="term"><code class="option">-b</code><br /></span><span class="term"><code class="option">--bkp-details</code></span></dt><dd><p>
+ Output detailed information about backup blocks.
+ </p></dd><dt><span class="term"><code class="option">-B <em class="replaceable"><code>block</code></em></code><br /></span><span class="term"><code class="option">--block=<em class="replaceable"><code>block</code></em></code></span></dt><dd><p>
+ Only display records that modify the given block. The relation must
+ also be provided with <code class="option">--relation</code> or
+ <code class="option">-R</code>.
+ </p></dd><dt><span class="term"><code class="option">-e <em class="replaceable"><code>end</code></em></code><br /></span><span class="term"><code class="option">--end=<em class="replaceable"><code>end</code></em></code></span></dt><dd><p>
+ Stop reading at the specified WAL location, instead of reading to the
+ end of the log stream.
+ </p></dd><dt><span class="term"><code class="option">-f</code><br /></span><span class="term"><code class="option">--follow</code></span></dt><dd><p>
+ After reaching the end of valid WAL, keep polling once per second for
+ new WAL to appear.
+ </p></dd><dt><span class="term"><code class="option">-F <em class="replaceable"><code>fork</code></em></code><br /></span><span class="term"><code class="option">--fork=<em class="replaceable"><code>fork</code></em></code></span></dt><dd><p>
+ If provided, only display records that modify blocks in the given fork.
+ The valid values are <code class="literal">main</code> for the main fork,
+ <code class="literal">fsm</code> for the free space map,
+ <code class="literal">vm</code> for the visibility map,
+ and <code class="literal">init</code> for the init fork.
+ </p></dd><dt><span class="term"><code class="option">-n <em class="replaceable"><code>limit</code></em></code><br /></span><span class="term"><code class="option">--limit=<em class="replaceable"><code>limit</code></em></code></span></dt><dd><p>
+ Display the specified number of records, then stop.
+ </p></dd><dt><span class="term"><code class="option">-p <em class="replaceable"><code>path</code></em></code><br /></span><span class="term"><code class="option">--path=<em class="replaceable"><code>path</code></em></code></span></dt><dd><p>
+ Specifies a directory to search for log segment files or a
+ directory with a <code class="literal">pg_wal</code> subdirectory that
+ contains such files. The default is to search in the current
+ directory, the <code class="literal">pg_wal</code> subdirectory of the
+ current directory, and the <code class="literal">pg_wal</code> subdirectory
+ of <code class="envar">PGDATA</code>.
+ </p></dd><dt><span class="term"><code class="option">-q</code><br /></span><span class="term"><code class="option">--quiet</code></span></dt><dd><p>
+ Do not print any output, except for errors. This option can be useful
+ when you want to know whether a range of WAL records can be
+ successfully parsed but don't care about the record contents.
+ </p></dd><dt><span class="term"><code class="option">-r <em class="replaceable"><code>rmgr</code></em></code><br /></span><span class="term"><code class="option">--rmgr=<em class="replaceable"><code>rmgr</code></em></code></span></dt><dd><p>
+ Only display records generated by the specified resource manager. You can
+ specify the option multiple times to select multiple resource managers.
+ If <code class="literal">list</code> is passed as name, print a list of valid resource manager
+ names, and exit.
+ </p><p>
+ Extensions may define custom resource managers, but pg_waldump does
+ not load the extension module and therefore does not recognize custom
+ resource managers by name. Instead, you can specify the custom
+ resource managers as <code class="literal">custom###</code> where
+ "<code class="literal">###</code>" is the three-digit resource manager ID. Names
+ of this form will always be considered valid.
+ </p></dd><dt><span class="term"><code class="option">-R <em class="replaceable"><code>tblspc</code></em>/<em class="replaceable"><code>db</code></em>/<em class="replaceable"><code>rel</code></em></code><br /></span><span class="term"><code class="option">--relation=<em class="replaceable"><code>tblspc</code></em>/<em class="replaceable"><code>db</code></em>/<em class="replaceable"><code>rel</code></em></code></span></dt><dd><p>
+ Only display records that modify blocks in the given relation. The
+ relation is specified with tablespace OID, database OID, and relfilenode
+ separated by slashes, for example <code class="literal">1234/12345/12345</code>.
+ This is the same format used for relations in the program's output.
+ </p></dd><dt><span class="term"><code class="option">-s <em class="replaceable"><code>start</code></em></code><br /></span><span class="term"><code class="option">--start=<em class="replaceable"><code>start</code></em></code></span></dt><dd><p>
+ WAL location at which to start reading. The default is to start reading
+ the first valid log record found in the earliest file found.
+ </p></dd><dt><span class="term"><code class="option">-t <em class="replaceable"><code>timeline</code></em></code><br /></span><span class="term"><code class="option">--timeline=<em class="replaceable"><code>timeline</code></em></code></span></dt><dd><p>
+ Timeline from which to read log records. The default is to use the
+ value in <em class="replaceable"><code>startseg</code></em>, if that is specified; otherwise, the
+ default is 1.
+ </p></dd><dt><span class="term"><code class="option">-V</code><br /></span><span class="term"><code class="option">--version</code></span></dt><dd><p>
+ Print the <span class="application">pg_waldump</span> version and exit.
+ </p></dd><dt><span class="term"><code class="option">-w</code><br /></span><span class="term"><code class="option">--fullpage</code></span></dt><dd><p>
+ Only display records that include full page images.
+ </p></dd><dt><span class="term"><code class="option">-x <em class="replaceable"><code>xid</code></em></code><br /></span><span class="term"><code class="option">--xid=<em class="replaceable"><code>xid</code></em></code></span></dt><dd><p>
+ Only display records marked with the given transaction ID.
+ </p></dd><dt><span class="term"><code class="option">-z</code><br /></span><span class="term"><code class="option">--stats[=record]</code></span></dt><dd><p>
+ 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.
+ </p><p>
+ If <span class="application">pg_waldump</span> is terminated by signal
+ <span class="systemitem">SIGINT</span>
+ (<span class="keycap"><strong>Control</strong></span>+<span class="keycap"><strong>C</strong></span>),
+ the summary of the statistics computed is displayed up to the
+ termination point. This operation is not supported on
+ <span class="productname">Windows</span>.
+ </p></dd><dt><span class="term"><code class="option">-?</code><br /></span><span class="term"><code class="option">--help</code></span></dt><dd><p>
+ Show help about <span class="application">pg_waldump</span> command line
+ arguments, and exit.
+ </p></dd></dl></div><p>
+ </p></div><div class="refsect1" id="id-1.9.5.13.7"><h2>Environment</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="envar">PGDATA</code></span></dt><dd><p>
+ Data directory; see also the <code class="option">-p</code> option.
+ </p></dd><dt><span class="term"><code class="envar">PG_COLOR</code></span></dt><dd><p>
+ Specifies whether to use color in diagnostic messages. Possible values
+ are <code class="literal">always</code>, <code class="literal">auto</code> and
+ <code class="literal">never</code>.
+ </p></dd></dl></div></div><div class="refsect1" id="id-1.9.5.13.8"><h2>Notes</h2><p>
+ Can give wrong results when the server is running.
+ </p><p>
+ Only the specified timeline is displayed (or the default, if none is
+ specified). Records in other timelines are ignored.
+ </p><p>
+ <span class="application">pg_waldump</span> cannot read WAL files with suffix
+ <code class="literal">.partial</code>. If those files need to be read, <code class="literal">.partial</code>
+ suffix needs to be removed from the file name.
+ </p></div><div class="refsect1" id="id-1.9.5.13.9"><h2>See Also</h2><span class="simplelist"><a class="xref" href="wal-internals.html" title="30.6. WAL Internals">Section 30.6</a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pgupgrade.html" title="pg_upgrade">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="reference-server.html" title="PostgreSQL Server Applications">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="app-postgres.html" title="postgres">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="application">pg_upgrade</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="40%" align="right" valign="top"> <span class="application">postgres</span></td></tr></table></div></body></html> \ No newline at end of file
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