Re: pg_upgrade and logical replication

On Tue, Sep 26, 2023 at 09:40:48AM +0530, Amit Kapila wrote:
> On Mon, Sep 25, 2023 at 11:43 AM Michael Paquier <michael@paquier.xyz> wrote:
>> Sure, that's assuming that the publisher side is upgraded.
> 
> At some point, user needs to upgrade publisher and subscriber could
> itself have some publications defined which means the downstream
> subscribers will have the same problem.

Not always.  I take it as a valid case that one may want to create a
logical setup only for the sake of an upgrade, and trashes the
publisher after a failover to an upgraded subscriber node after the
latter has done a sync up of the data that's been added to the
relations tracked by the publications while the subscriber was
pg_upgrade'd.

>>> This is the primary reason why I prioritized to work on the publisher
>>> side before getting this patch done, otherwise, the solution for this
>>> patch was relatively clear. I am not sure but I guess this could be
>>> the reason why originally we left it in the current state, otherwise,
>>> restoring subscription rel's or origin doesn't seem to be too much of
>>> an additional effort than what we are doing now.
>>
>> By "additional effort", you are referring to what the patch is doing,
>> with the binary dump of pg_subscription_rel, right?
>>
> 
> Yes.

Okay.  I'd like to move on with this stuff, then.  At least it helps
in maintaining data integrity when doing an upgrade with a logical
setup.  The patch still needs more polishing, though..
--
Michael