On Fri, Oct 24, 2025 at 11:43 AM shveta malik <shveta.malik@gmail.com> wrote:
>
> 5)
> For the race condition where the worker is going to access the seq
> locally and meanwhile it is altered; now the worker correctly reports
> this. But it reports this as a success scenario. And once the scenario
> is reported as 'seq-worker finished', we do not expect it to start
> running again without the user doing REFRESH. But in this case, it
> runs, see logs. Also it starts immediately for once due to the same
> reason that start_time is reset in the success scenario.
> -------
> 17:35:05.618 IST [132551] LOG: logical replication apply worker for
> subscription "sub1" has started
> 17:35:05.637 IST [132553] LOG: logical replication sequence
> synchronization worker for subscription "sub1" has started
> 17:35:05.663 IST [132553] LOG: logical replication sequence
> synchronization for subscription "sub1" - total unsynchronized: 1
> 17:36:11.987 IST [132553] LOG: skip synchronization of sequence
> "public.myseq249" because it has been altered concurrently
> 17:36:19.614 IST [132553] LOG: logical replication sequence
> synchronization for subscription "sub1" - batch #1 = 1 attempted, 0
> succeeded, 1 skipped, 0 mismatched, 0 insufficient permission, 0
> missing from publisher
> 17:36:20.335 IST [132553] LOG: logical replication sequence
> synchronization worker for subscription "sub1" has finished
> 17:36:20.435 IST [132586] LOG: logical replication sequence
> synchronization worker for subscription "sub1" has started
> 17:36:20.545 IST [132586] LOG: logical replication sequence
> synchronization for subscription "sub1" - total unsynchronized: 1
> -------
>
> The behaviour looks slightly odd. Is there anything we can do about
> this? Shall the skipped case be reported as ERROR due to the fact that
> we leave it in state 'i' in pg_subscription_rel?
>
The downside of reporting an ERROR as soon as we can't sync values for
one of the sequences is that the other sequences which could be synced
won't get synced. The other possibility is that we skip processing
such a sequence while copying sequences but at the end if there is any
pending sequence which is not synced, we raise an ERROR. If we do that
then we may need to give some generic ERROR because there could be
multiple such sequences. The other possibility is that we can give a
LOG message like "logical replication sequence sync worker for
subscription \"%s\" will restart because ..." and then do proc_exit(1)
without resetting restart_time. Will that help to address your
concern?
--
With Regards,
Amit Kapila.
