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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>51.2. Archive Module Callbacks</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="archive-module-init.html" title="51.1. Initialization Functions" /><link rel="next" href="reference.html" title="Part VI. Reference" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">51.2. Archive Module Callbacks</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="archive-module-init.html" title="51.1. Initialization Functions">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="archive-modules.html" title="Chapter 51. Archive Modules">Up</a></td><th width="60%" align="center">Chapter 51. Archive Modules</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="reference.html" title="Part VI. Reference">Next</a></td></tr></table><hr /></div><div class="sect1" id="ARCHIVE-MODULE-CALLBACKS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">51.2. Archive Module Callbacks <a href="#ARCHIVE-MODULE-CALLBACKS" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="archive-module-callbacks.html#ARCHIVE-MODULE-STARTUP">51.2.1. Startup Callback</a></span></dt><dt><span class="sect2"><a href="archive-module-callbacks.html#ARCHIVE-MODULE-CHECK">51.2.2. Check Callback</a></span></dt><dt><span class="sect2"><a href="archive-module-callbacks.html#ARCHIVE-MODULE-ARCHIVE">51.2.3. Archive Callback</a></span></dt><dt><span class="sect2"><a href="archive-module-callbacks.html#ARCHIVE-MODULE-SHUTDOWN">51.2.4. Shutdown Callback</a></span></dt></dl></div><p>
The archive callbacks define the actual archiving behavior of the module.
The server will call them as required to process each individual WAL file.
</p><div class="sect2" id="ARCHIVE-MODULE-STARTUP"><div class="titlepage"><div><div><h3 class="title">51.2.1. Startup Callback <a href="#ARCHIVE-MODULE-STARTUP" class="id_link">#</a></h3></div></div></div><p>
The <code class="function">startup_cb</code> callback is called shortly after the
module is loaded. This callback can be used to perform any additional
initialization required. If the archive module has any state, it can use
<code class="structfield">state->private_data</code> to store it.
</p><pre class="programlisting">
typedef void (*ArchiveStartupCB) (ArchiveModuleState *state);
</pre><p>
</p></div><div class="sect2" id="ARCHIVE-MODULE-CHECK"><div class="titlepage"><div><div><h3 class="title">51.2.2. Check Callback <a href="#ARCHIVE-MODULE-CHECK" class="id_link">#</a></h3></div></div></div><p>
The <code class="function">check_configured_cb</code> callback is called to determine
whether the module is fully configured and ready to accept WAL files (e.g.,
its configuration parameters are set to valid values). If no
<code class="function">check_configured_cb</code> is defined, the server always
assumes the module is configured.
</p><pre class="programlisting">
typedef bool (*ArchiveCheckConfiguredCB) (ArchiveModuleState *state);
</pre><p>
If <code class="literal">true</code> is returned, the server will proceed with
archiving the file by calling the <code class="function">archive_file_cb</code>
callback. If <code class="literal">false</code> is returned, archiving will not
proceed, and the archiver will emit the following message to the server log:
</p><pre class="screen">
WARNING: archive_mode enabled, yet archiving is not configured
</pre><p>
In the latter case, the server will periodically call this function, and
archiving will proceed only when it returns <code class="literal">true</code>.
</p></div><div class="sect2" id="ARCHIVE-MODULE-ARCHIVE"><div class="titlepage"><div><div><h3 class="title">51.2.3. Archive Callback <a href="#ARCHIVE-MODULE-ARCHIVE" class="id_link">#</a></h3></div></div></div><p>
The <code class="function">archive_file_cb</code> callback is called to archive a
single WAL file.
</p><pre class="programlisting">
typedef bool (*ArchiveFileCB) (ArchiveModuleState *state, const char *file, const char *path);
</pre><p>
If <code class="literal">true</code> is returned, the server proceeds as if the file
was successfully archived, which may include recycling or removing the
original WAL file. If <code class="literal">false</code> is returned, the server will
keep the original WAL file and retry archiving later.
<em class="replaceable"><code>file</code></em> will contain just the file name of the WAL
file to archive, while <em class="replaceable"><code>path</code></em> contains the full
path of the WAL file (including the file name).
</p></div><div class="sect2" id="ARCHIVE-MODULE-SHUTDOWN"><div class="titlepage"><div><div><h3 class="title">51.2.4. Shutdown Callback <a href="#ARCHIVE-MODULE-SHUTDOWN" class="id_link">#</a></h3></div></div></div><p>
The <code class="function">shutdown_cb</code> callback is called when the archiver
process exits (e.g., after an error) or the value of
<a class="xref" href="runtime-config-wal.html#GUC-ARCHIVE-LIBRARY">archive_library</a> changes. If no
<code class="function">shutdown_cb</code> is defined, no special action is taken in
these situations. If the archive module has any state, this callback should
free it to avoid leaks.
</p><pre class="programlisting">
typedef void (*ArchiveShutdownCB) (ArchiveModuleState *state);
</pre><p>
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