Re: Make wal_receiver_timeout configurable per subscription

On Fri, May 16, 2025 at 9:11 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
> When multiple subscribers connect to different publisher servers,
> it can be useful to set different wal_receiver_timeout values for
> each connection to better detect failures. However, this isn't
> currently possible, which limits flexibility in managing subscriptions.
>
> To address this, I'd like to propose making wal_receiver_timeout
> configurable per subscription.
>
> One approach is to add wal_receiver_timeout as a parameter to
> CREATE SUBSCRIPTION command, storing it in pg_subscription
> so each logical replication worker can use its specific value.
>
> Another option is to change the wal_receiver_timeout's GUC context
> from PGC_SIGHUP to PGC_USERSET. This would allow setting different
> values via ALTER ROLE SET command for each subscription owner -
> effectively enabling per-subscription configuration. Since this
> approach is simpler and likely sufficient, I'd prefer starting with this.
> Thought?
>

The GUC wal_receiver_interval is also used for physical replication
and logical launcher, so won't making it userset can impact those
cases as well, but maybe that is okay. However, for the specific case
you are worried about, isn't it better to make it a subscription
option as that won't have a chance to impact any other cases?

IIUC, the reason you are worried is because different publishers can
have different network latencies with subscribers, so they may want
different timing for feedback/keepalive messages.

--
With Regards,
Amit Kapila.