Re: pg_upgrade and logical replication

On Sat, Nov 25, 2023 at 7:21 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>

Few comments on v19:
==================
1.
+ <para>
+ The subscriptions will be migrated to the new cluster in a disabled state.
+ After migration, do this:
+ </para>
+
+ <itemizedlist>
+ <listitem>
+ <para>
+ Enable the subscriptions by executing
+ <link linkend="sql-altersubscription"><command>ALTER
SUBSCRIPTION ... ENABLE</command></link>.

The reason for this restriction is not very clear to me. Is it because
we are using pg_dump for subscription and the existing functionality
is doing it? If so, I think currently even connect is false.

2.
+ * b) SUBREL_STATE_SYNCDONE: A relation upgraded while in this state
+ * would retain the replication origin in certain cases.

I think this is vague. Can we briefly describe cases where the origins
would be retained?

3. I think the cases where the publisher is also upgraded restoring
the origin's LSN is of no use. Currently, I can't see a problem with
restoring stale originLSN in such cases as we won't be able to
distinguish during the upgrade but I think we should document it in
the comments somewhere in the patch.

--
With Regards,
Amit Kapila.