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
     <xref linkend="logical-replication"/>).
    </para>

    <para>
     For <emphasis>streaming replication</emphasis>, servers will be either a
     primary or a standby server.  Primaries can send data, while standbys
     are always receivers of replicated data.  When cascading replication
     (see <xref linkend="cascading-replication"/>) is used, standby servers
     can also be senders, as well as receivers.
     Parameters are mainly for sending and standby servers, though some
     parameters have meaning only on the primary server.  Settings may vary
     across the cluster without problems if that is required.
    </para>

    <para>
     For <emphasis>logical replication</emphasis>, <firstterm>publishers</firstterm>
     (servers that do <link linkend="sql-createpublication"><command>CREATE PUBLICATION</command></link>)
     replicate data to <firstterm>subscribers</firstterm>
     (servers that do <link linkend="sql-createsubscription"><command>CREATE SUBSCRIPTION</command></link>).
     Servers can also be publishers and subscribers at the same time. Note,
     the following sections refer to publishers as "senders". For more details
     about logical replication configuration settings refer to
     <xref linkend="logical-replication-config"/>.
    </para>

    <sect2 id="runtime-config-replication-sender">
     <title>Sending Servers</title>

     <para>
      These parameters can be set on any server that is
      to send replication data to one or more standby servers.
      The primary is always a sending server, so these parameters must
      always be set on the primary.
      The role and meaning of these parameters does not change after a
      standby becomes the primary.
     </para>

     <variablelist>
      <varlistentry id="guc-max-wal-senders" xreflabel="max_wal_senders">
       <term><varname>max_wal_senders</varname> (<type>integer</type>)
       <indexterm>
        <primary><varname>max_wal_senders</varname> configuration parameter</primary>
       </indexterm>
       </term>
       <listitem>
       <para>
        Specifies the maximum number of concurrent connections from standby
        servers or streaming base backup clients (i.e., the maximum number of
        simultaneously running WAL sender processes). The default is
        <literal>10</literal>.  The value <literal>0</literal> means
        replication is disabled.  Abrupt disconnection of a streaming client might
        leave an orphaned connection slot behind until a timeout is reached,
        so this parameter should be set slightly higher than the maximum
        number of expected clients so disconnected clients can immediately
        reconnect.  This parameter can only be set at server start.  Also,
        <varname>wal_level</varname> must be set to
        <literal>replica</literal> or higher to allow connections from standby
        servers.
       </para>

       <para>
         When running a standby server, you must set this parameter to