Re: Exit walsender before confirming remote flush in logical replication

On Wed, Feb 8, 2023 at 7:57 AM Kyotaro Horiguchi
<horikyota(dot)ntt(at)gmail(dot)com> wrote:
>
> I agree to the direction and thanks for the patch.
>
> At Tue, 7 Feb 2023 17:08:54 +0000, "Hayato Kuroda (Fujitsu)" <kuroda(dot)hayato(at)fujitsu(dot)com> wrote in
> > > I noticed that previous ones are rejected by cfbot, even if they passed on my
> > > environment...
> > > PSA fixed version.
> >
> > While analyzing more, I found the further bug that forgets initialization.
> > PSA new version that could be passed automated tests on my github repository.
> > Sorry for noise.
>
> 0002:
>
> This patch doesn't seem to offer a means to change the default
> walsender behavior. We need a subscription option named like
> "walsender_exit_mode" to do that.
>

I don't think at this stage we need a subscription-level option, we
can extend it later if this is really useful for users. For now, we
can set this new option when min_apply_delay > 0.

>
> +ConsumeWalsenderOptions(List *options, WalSndData *data)
>
> I wonder if it is the right design to put options for different things
> into a single list. I rather choose to embed the walsender option in
> the syntax than needing this function.
>
> K_START_REPLICATION opt_slot opt_physical RECPTR opt_timeline opt_shutdown_mode
>
> K_START_REPLICATION K_SLOTIDENT K_LOGICAL RECPTR opt_shutdown_mode plugin_options
>
> where opt_shutdown_mode would be like "SHUTDOWN_MODE immediate".
>

The other option could have been that we just add it as a
plugin_option for logical replication but it doesn't seem to match
with the other plugin options. I think it would be better to have it
as a separate option something like opt_shutdown_immediate and extend
the logical replication syntax for now. We can later extend physical
replication syntax when we want to expose such an option via physical
replication.

--
With Regards,
Amit Kapila.