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

On Thu, Mar 26, 2026, 00:30 Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:

> On Wed, Mar 25, 2026 at 4:03 PM Shinya Kato <shinya11(dot)kato(at)gmail(dot)com>
> wrote:
> > Thanks for the updated patch. LGTM.
> >
> > Regarding the backpatch, I'd personally appreciate it if the walsender.c
> changes were backpatched to stable branches. As you noted, it don't fully
> solve the reported issue, but they do help reduce the cases where lag
> columns in pg_stat_replication unexpectedly become NULL.
> >
> > Even a partial mitigation in the back branches would be valuable for
> users running stable releases.
>
> +1
>
> I've split the changes into two patches.
>
> Patch 0001 fixes premature NULL lag reporting in walsender. I will commit
> it
> and backpatch it to all supported branches.
>
> Patch 0002 avoids sending duplicate WAL locations in standby status
> replies.
> I will commit this to master only.
>

Thanks, LGTM.

Best regards,
Shinya Kato

>