Re: Retry Cached Remote Connections for postgres_fdw in case remote backend gets killed/goes away

On Thu, Oct 1, 2020 at 8:10 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
> pg_stat_clear_snapshot() can be used to reset the entry.
>

Thanks. I wasn't knowing it.

>
> + EXIT WHEN proccnt = 0;
> + END LOOP;
>
> Isn't it better to sleep here, to avoid th busy loop?
>

+1.

>
> So what I thought was something like
>
> CREATE OR REPLACE PROCEDURE wait_for_backend_termination()
> LANGUAGE plpgsql
> AS $$
> BEGIN
> LOOP
> PERFORM * FROM pg_stat_activity WHERE application_name = 'fdw_retry_check';
> EXIT WHEN NOT FOUND;
> PERFORM pg_sleep(1), pg_stat_clear_snapshot();
> END LOOP;
> END;
> $$;
>

Changed.

Attaching v8 patch, please review it.. Both make check and make
check-world passes on v8.

I have another question not related to this patch: though we have
wait_pid() function, we are not able to use it like
pg_terminate_backend() in other modules, wouldn't be nice if we can
make it generic under the name pg_wait_pid() and usable across all pg
modules?

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com