Re: pg_stat_replication.*_lag sometimes shows NULL during active replication

On Mon, Mar 16, 2026 at 9:26 AM Shinya Kato <shinya11(dot)kato(at)gmail(dot)com> wrote:
> Thank you for the v4 patch. I think this approach is better than mine.
> I tested the patch and confirmed that the issue no longer reproduces
> with physical replication. However, with logical replication, the lag
> columns in pg_stat_replication still show NULL periodically at
> wal_receiver_status_interval, since send_feedback() in worker.c can
> still send duplicate positions.

I was thinking that if a feedback message triggered by
wal_receiver_status_interval has the same LSNs as the previous message,
it's expected for the lag columns to become NULL. But you see it differently,
don't you? Sorry, I failed to understand your point...

Regards,

--
Fujii Masao