Re: State of pg_createsubscriber

On Tue, Jun 18, 2024 at 12:13 PM Peter Eisentraut <peter@eisentraut.org> wrote:
>
> On 18.06.24 05:59, Amit Kapila wrote:
> >> 1. After promotion, the pre-existing replication objects should be
> >> removed (either optionally or always), otherwise, it can lead to a new
> >> subscriber not being able to restart or getting some unwarranted data.
> >> [1][2].
> >>
> >> 2. Retaining synced slots on new subscribers can lead to unnecessary
> >> WAL retention and dead rows [3].
> >>
> >> 3. We need to consider whether some of the messages displayed in
> >> --dry-run mode are useful or not [4].
> >>
> >
> > The recent commits should silence BF failures and resolve point number
> > 2. But we haven't done anything yet for 1 and 3. For 3, we have a
> > patch in email [1] (v3-0005-Avoid*) which can be reviewed and
> > committed but point number 1 needs discussion. Apart from that
> > somewhat related to point 1, Kuroda-San has raised a point in an email
> > [2] for replication slots. Shlok has presented a case in this thread
> > [3] where the problem due to point 1 can cause ERRORs or can cause
> > data inconsistency.
> >
> > Now, the easiest way out here is that we accept the issues with the
> > pre-existing subscriptions and replication slots cases and just
> > document them for now with the intention to work on those in the next
> > version. OTOH, if there are no major challenges, we can try to
> > implement a patch for them as well as see how it goes.
>
> This has gotten much too confusing to keep track of.
>
> I suggest, if anyone has anything they want considered for
> pg_createsubscriber for PG17 at this point, they start a new thread, one
> for each topic, ideally with a subject like "pg_createsubscriber:
> Improve this thing", provide a self-contained description of the issue,
> and include a patch if one is available.
>

Fair enough. In my mind, we have three pending issues to discuss and I
have responded to an email to see if Euler can start individual
threads for those, otherwise, I'll do it.

We can close the open item pointing to this thread.

--
With Regards,
Amit Kapila.