Re: pg_upgrade and logical replication

On Thu, Sep 21, 2023 at 4:39 AM Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>
> On Wed, Sep 20, 2023 at 04:54:36PM +0530, Amit Kapila wrote:
> > Also, the patch seems to be allowing subscription relations from PG
> > >=10 to be migrated but how will that work if the corresponding
> > publisher is also upgraded without slots? Won't the corresponding
> > workers start failing as soon as you restart the upgrade server? Do we
> > need to document the steps for users?
>
> Hmm? How is that related to the upgrade of the subscribers?
>

It is because after upgrade of both publisher and subscriber, the
subscriptions won't work. Both publisher and subscriber should work,
otherwise, the logical replication set up won't work. I think we can
probably do this, if we can document clearly how the user can make
their logical replication set up work after upgrade.

>
> And how
> is that different from the case where a subscriber tries to connect
> back to a publisher where a slot has been dropped?
>

It is different because we don't drop slots automatically anywhere else.

--
With Regards,
Amit Kapila.