Re: Impact of checkpointer during pg_upgrade

On Tue, Sep 5, 2023 at 10:55 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> > Earlier I was thinking that ERRORing out is better so that the user
> > can take necessary action for the invalidated slots and then retry
> > upgrade. But thinking again I could not find what are the advantages
> > of this because if we error out then also users need to restart the
> > old cluster again and have to drop the corresponding subscriptions
> > OTOH if we allow the upgrade by ignoring the slots then also the user
> > has to take similar actions on the new cluster? So what's the
> > advantage of erroring out over upgrading?
> >
>
> The advantage is that we avoid inconvenience caused to users because
> Drop Subscription will be unsuccessful as the corresponding slots are
> not present. So users first need to disassociate slots for the
> subscription and then drop the subscription.

Yeah that's a valid argument for erroring out.

Also, I am not sure
> leaving behind some slots doesn't have any other impact, otherwise,
> why don't we drop such slots from time to time after they are marked
> invalidated during normal operation?

Okay, I am also not sure of that.

If users really want to leave
> behind such invalidated slots after upgrade, we can even think of
> providing some option like "exclude_invalid_logical_slots".

+1

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com