doc: pg_upgrade, clarify standby servers must remain running

Also mention that mismatching primary/standby LSNs should never
happen.

Reported-by: Nikolay Samokhvalov
Discussion: https://postgr.es/m/CAM527d8heqkjG5VrvjU3Xjsqxg41ufUyabD9QZccdAxnpbRH-Q@mail.gmail.com

Backpatch-through: 11

diff --git a/doc/src/sgml/ref/pgupgrade.sgml b/doc/src/sgml/ref/pgupgrade.sgml
index bea0d1b93f930ee074dbf3f094e656fdb58e8eca..958c44b361631cb5261014fd29f619fed0ac8b2f 100644 (file)
--- a/doc/src/sgml/ref/pgupgrade.sgml
+++ b/doc/src/sgml/ref/pgupgrade.sgml
@@ -403,8 +403,8 @@ NET STOP postgresql-&majorversion;
     </para>
 
     <para>
-     Streaming replication and log-shipping standby servers can
-     remain running until a later step.
+     Streaming replication and log-shipping standby servers must be
+     running during this shutdown so they receive all changes.
     </para>
    </step>
 
@@ -417,8 +417,6 @@ NET STOP postgresql-&majorversion;
      servers are caught up by running <application>pg_controldata</application>
      against the old primary and standby clusters.  Verify that the
      <quote>Latest checkpoint location</quote> values match in all clusters.
-     (There will be a mismatch if old standby servers were shut down
-     before the old primary or if the old standby servers are still running.)
      Also, make sure <varname>wal_level</varname> is not set to
      <literal>minimal</literal> in the <filename>postgresql.conf</filename> file on the
      new primary cluster.