Re: Logical Replication of sequences

On Sun, Oct 5, 2025 at 7:54 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Sat, Oct 04, 2025 at 09:24:32PM +0530, Amit Kapila wrote:
> > In the 0001 patch, pg_get_sequence_data() exposes two new fields
> > log_cnt and page_lsn. I see that the later subscriber-side patch uses
> > both, the first one in SetSequence(). It is not clear from the
> > comments or the commit message of 0001 why it is necessary to use
> > log_cnt when setting the sequence. Can you explain what the problem
> > will be if we don't use log_cnt during sequence sync?
>
> FWIW, I have argued two times at least that it should never be
> necessary to expose log_cnt in the sequence meta-data: this is just a
> counter to decide when a WAL record of a sequence should be generated.
>
> If you are copying some sequence data over the wire on a new node in a
> logical shape where WAL is independent, this counter is irrelevant:
> you can just reset it.  Please see also a83a944e9fdd.
>

Agreed and I think we have the same behaviour after upgrade.

--
With Regards,
Amit Kapila.