title: upgrade to PostgreSQL 12 in cluster
body: <p>I have two node PostgreSQL 11 HA setup as follows.</p>
  
  <p>node1 - hamaster.myorg.net</p>
  
  <p>node2 - haslave.myorg.net</p>
  
  <p><code>recovery.conf</code> on node2 is as follows:</p>
  
  <pre><code>standby_mode          = 'on'
  primary_conninfo      = 'host=hamaster.myorg.net port=5432 user=&lt;user_here&gt; password=&lt;password_here&gt; sslmode=require sslcompression=0'
  trigger_file = '/tmp/MasterNow'
  recovery_target_timeline = 'latest' 
  </code></pre>
  
  <p>I want to upgrade PostgreSQL to 12 on both the system. I have identified following steps in exact sequence:</p>
  
  <ol>
  <li>Stop PostgreSQL on master node.</li>
  <li>Update the RPM (i am using centos 7.8) to PostgreSQL 12 on master node and upgrade the PostgreSQL using <code>pg_upgrade</code></li>
  <li>Start the PostgreSQL on master node.</li>
  <li>Stop the PostgreSQL on slave node.</li>
  <li>Update the RPM (i am using centos 7.8) to PostgreSQL 12 on slave node and upgrade the PostgreSQL using <code>pg_upgrade</code></li>
  <li>On slave node, copy the contents from <code>recovery.conf</code> to <code>postgresql.conf</code> and remove the <code>recovery.conf</code>. Also create the file <code>standby.signal</code> in data directory on slave server. Rename <code>trigger_file</code> to <code>promote_trigger_file</code>. Remove the line <code>standby_mode          = 'on'</code> as this is NOT required by PostgreSQL 12.</li>
  <li>Start the PostgreSQL on slave node.</li>
  </ol>
  
  <p>Is there anything missing?</p>