Thread

Re: Fix lag columns in pg_stat_replication not advancing when replay LSN stalls

Shinya Kato <shinya11.kato@gmail.com> — 2025-10-20T04:45:01Z

On Mon, Oct 20, 2025 at 10:17 AM Fujii Masao <masao.fujii@gmail.com> wrote:
>
> On Sun, Oct 19, 2025 at 2:04 AM Shinya Kato <shinya11.kato@gmail.com> wrote:
> > Thank you for the patch. I have one comment.
> >
> > +       if (lag_tracker->overflowed[head].lsn > lsn)
> > +           return now - lag_tracker->overflowed[head].time;
> >
> > Could this return a negative value if the clock somehow went
> > backwards? The original code returns -1 in this case, so I'm curious
> > about this.
>
> Thanks for the review!
>
> Yes, you're right. So I've updated the patch so that -1 is returned
> when the current time is earlier than the time in the overflow entry,
> treating it as "no new sample found".

Thank you for updating the patch. It looks nice to me.

-- 
Best regards,
Shinya Kato
NTT OSS Center