recovery target is set.
        If <xref linkend="guc-hot-standby"/> is not enabled, a setting of
        <literal>pause</literal> will act the same as <literal>shutdown</literal>.
        If the recovery target is reached while a promotion is ongoing,
        a setting of <literal>pause</literal> will act the same as
        <literal>promote</literal>.
       </para>
       <para>
        In any case, if a recovery target is configured but the archive
        recovery ends before the target is reached, the server will shut down
        with a fatal error.
       </para>
      </listitem>
     </varlistentry>

    </variablelist>
   </sect2>

   <sect2 id="runtime-config-wal-summarization">
    <title>WAL Summarization</title>

    <para>
     These settings control WAL summarization, a feature which must be
     enabled in order to perform an
     <link linkend="backup-incremental-backup">incremental backup</link>.
    </para>

    <variablelist>
     <varlistentry id="guc-summarize-wal" xreflabel="summarize_wal">
      <term><varname>summarize_wal</varname> (<type>boolean</type>)
      <indexterm>
       <primary><varname>summarize_wal</varname> configuration parameter</primary>
      </indexterm>
      </term>
     <listitem>
      <para>
       Enables the WAL summarizer process. Note that WAL summarization can
       be enabled either on a primary or on a standby.  This parameter can only
       be set in the <filename>postgresql.conf</filename> file or on the server
       command line.  The default is <literal>off</literal>.
      </para>
      <para>
       The server cannot be started with <literal>summarize_wal=on</literal>
       if <literal>wal_level</literal> is set to <literal>minimal</literal>. If
       <literal>summarize_wal=on</literal> is configured after server startup
       while <literal>wal_level=minimal</literal>, the summarizer will run
       but refuse to generate summary files for any WAL generated with
       <literal>wal_level=minimal</literal>.
      </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-wal-summary-keep-time" xreflabel="wal_summary_keep_time">
      <term><varname>wal_summary_keep_time</varname> (<type>integer</type>)
      <indexterm>
       <primary><varname>wal_summary_keep_time</varname> configuration parameter</primary>
      </indexterm>
      </term>
     <listitem>
      <para>
       Configures the amount of time after which the WAL summarizer
       automatically removes old WAL summaries. The file timestamp is used to
       determine which files are old enough to remove. Typically, you should set
       this comfortably higher than the time that could pass between a backup
       and a later incremental backup that depends on it.  WAL summaries must
       be available for the entire range of WAL records between the preceding
       backup and the new one being taken; if not, the incremental backup will
       fail. If this parameter is set to zero, WAL summaries will not be
       automatically deleted, but it is safe to manually remove files that you
       know will not be required for future incremental backups.
       This parameter can only be set in the
       <filename>postgresql.conf</filename> file or on the server command line.
       If this value is specified without units, it is taken as minutes.
       The default is 10 days. If <literal>summarize_wal = off</literal>,
       existing WAL summaries will not be removed regardless of the value of
       this parameter, because the WAL summarizer will not run.
      </para>
      </listitem>
     </varlistentry>

    </variablelist>

   </sect2>

   </sect1>

   <sect1 id="runtime-config-replication">
    <title>Replication</title>

    <para>
     These settings control the behavior of the built-in
     <firstterm>streaming replication</firstterm> feature (see
     <xref linkend="streaming-replication"/>), and the built-in
     <firstterm>logical replication</firstterm> feature (see