<para>
        Upgrade the <literal>node3</literal>'s server to the required
        new version, e.g.:
<programlisting>
pg_upgrade
        --old-datadir "/opt/PostgreSQL/postgres/17/data3"
        --new-datadir "/opt/PostgreSQL/postgres/18/data3_upgraded"
        --old-bindir "/opt/PostgreSQL/postgres/17/bin"
        --new-bindir "/opt/PostgreSQL/postgres/18/bin"
</programlisting>
       </para>
      </step>

      <step>
       <para>
        Start the upgraded server in <literal>node3</literal>, e.g.:
<programlisting>
pg_ctl -D /opt/PostgreSQL/data3_upgraded start -l logfile
</programlisting>
       </para>
      </step>

      <step>
       <para>
        On <literal>node3</literal>, create any tables that were created in
        the upgraded <literal>node2</literal> between
        <xref linkend="cascaded-cluster-disable-sub-node2-node3"/> and now,
        e.g.:
<programlisting>
/* node3 # */ CREATE TABLE distributors (did integer PRIMARY KEY, name varchar(40));
</programlisting>
       </para>
      </step>

      <step>
       <para>
        Enable all the subscriptions on <literal>node3</literal> that are
        subscribing the changes from <literal>node2</literal> by using
        <link linkend="sql-altersubscription-params-enable"><command>ALTER SUBSCRIPTION ... ENABLE</command></link>,
        e.g.:
<programlisting>
/* node3 # */ ALTER SUBSCRIPTION sub1_node2_node3 ENABLE;
</programlisting>
       </para>
      </step>

      <step>
       <para>
        Refresh the <literal>node3</literal> subscription's publications using
        <link linkend="sql-altersubscription-params-refresh-publication"><command>ALTER SUBSCRIPTION ... REFRESH PUBLICATION</command></link>,
        e.g.:
<programlisting>
/* node3 # */ ALTER SUBSCRIPTION sub1_node2_node3 REFRESH PUBLICATION;
</programlisting>
       </para>
      </step>
     </procedure>
    </sect3>

    <sect3 id="steps-two-node-circular-logical-replication-cluster">
     <title>Steps to upgrade a two-node circular logical replication cluster</title>
     <para>
      Let's say we have a circular logical replication setup
      <literal>node1</literal>-><literal>node2</literal> and
      <literal>node2</literal>-><literal>node1</literal>. Here
      <literal>node2</literal> is subscribing the changes from
      <literal>node1</literal> and <literal>node1</literal> is subscribing
      the changes from <literal>node2</literal>. The <literal>node1</literal>
      has a subscription <literal>sub1_node2_node1</literal> which is
      subscribing the changes from <literal>node2</literal>. The
      <literal>node2</literal> has a subscription
      <literal>sub1_node1_node2</literal> which is subscribing the changes from
      <literal>node1</literal>.
     </para>

     <procedure>
      <step id="circular-cluster-disable-sub-node2">
       <para>
        Disable all the subscriptions on <literal>node2</literal> that are
        subscribing the changes from <literal>node1</literal> by using
        <link linkend="sql-altersubscription-params-disable"><command>ALTER SUBSCRIPTION ... DISABLE</command></link>,
        e.g.:
<programlisting>
/* node2 # */ ALTER SUBSCRIPTION sub1_node1_node2 DISABLE;
</programlisting>
       </para>
      </step>

      <step>
       <para>
        Stop the server in <literal>node1</literal>, e.g.:
<programlisting>
pg_ctl -D /opt/PostgreSQL/data1 stop
</programlisting>
       </para>
      </step>

      <step>
       <para>
        Initialize <literal>data1_upgraded</literal> instance by using the
        required newer version.
       </para>
      </step>

      <step>
       <para>
        Upgrade the <literal>node1</literal>'s server to the required
        newer version, e.g.:
<programlisting>
pg_upgrade
        --old-datadir "/opt/PostgreSQL/postgres/17/data1"
        --new-datadir "/opt/PostgreSQL/postgres/18/data1_upgraded"
        --old-bindir "/opt/PostgreSQL/postgres/17/bin"
        --new-bindir "/opt/PostgreSQL/postgres/18/bin"
</programlisting>