same or higher value than on the primary server. Otherwise, queries
        will not be allowed in the standby server.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-reserved-connections" xreflabel="reserved_connections">
      <term><varname>reserved_connections</varname> (<type>integer</type>)
      <indexterm>
       <primary><varname>reserved_connections</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Determines the number of connection <quote>slots</quote> that are
        reserved for connections by roles with privileges of the
        <xref linkend="predefined-role-pg-use-reserved-connections"/>
        role.  Whenever the number of free connection slots is greater than
        <xref linkend="guc-superuser-reserved-connections"/> but less than or
        equal to the sum of <varname>superuser_reserved_connections</varname>
        and <varname>reserved_connections</varname>, new connections will be
        accepted only for superusers and roles with privileges of
        <literal>pg_use_reserved_connections</literal>.  If
        <varname>superuser_reserved_connections</varname> or fewer connection
        slots are available, new connections will be accepted only for
        superusers.
       </para>

       <para>
        The default value is zero connections.  The value must be less than
        <varname>max_connections</varname> minus
        <varname>superuser_reserved_connections</varname>.  This parameter can
        only be set at server start.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-superuser-reserved-connections"
     xreflabel="superuser_reserved_connections">
      <term><varname>superuser_reserved_connections</varname>
      (<type>integer</type>)
      <indexterm>
       <primary><varname>superuser_reserved_connections</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Determines the number of connection <quote>slots</quote> that
        are reserved for connections by <productname>PostgreSQL</productname>
        superusers.  At most <xref linkend="guc-max-connections"/>
        connections can ever be active simultaneously.  Whenever the
        number of active concurrent connections is at least
        <varname>max_connections</varname> minus
        <varname>superuser_reserved_connections</varname>, new
        connections will be accepted only for superusers.  The connection slots
        reserved by this parameter are intended as final reserve for emergency
        use after the slots reserved by
        <xref linkend="guc-reserved-connections"/> have been exhausted.
       </para>

       <para>
        The default value is three connections. The value must be less
        than <varname>max_connections</varname> minus
        <varname>reserved_connections</varname>.
        This parameter can only be set at server start.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="guc-unix-socket-directories" xreflabel="unix_socket_directories">
      <term><varname>unix_socket_directories</varname> (<type>string</type>)
      <indexterm>
       <primary><varname>unix_socket_directories</varname> configuration parameter</primary>
      </indexterm>
      </term>
      <listitem>
       <para>
        Specifies the directory of the Unix-domain socket(s) on which the
        server is to listen for connections from client applications.
        Multiple sockets can be created by listing multiple directories
        separated by commas.  Whitespace between entries is
        ignored; surround a directory name with double quotes if you need
        to include whitespace or commas in the name.
        An empty value
        specifies not listening on any Unix-domain sockets, in which case
        only TCP/IP sockets can be used to connect to the server.
       </para>

       <para>