Re: wake up logical workers after ALTER SUBSCRIPTION

On Wed, Jan 4, 2023 at 11:03 PM Nathan Bossart <nathandbossart(at)gmail(dot)com> wrote:
>
> On Wed, Jan 04, 2023 at 09:41:47AM +0530, Amit Kapila wrote:
> > I am not sure if I understand the problem you are trying to solve with
> > this part of the patch. Are you worried that after we mark some of the
> > relation's state as READY, all the table syncs are in the READY state
> > but we will not immediately try to check the two_pahse stuff and
> > probably the apply worker may sleep before the next time it invokes
> > process_syncing_tables_for_apply()?
>
> Yes.
>
> > If so, we probably also need to
> > ensure that table_states_valid is marked false probably via
> > invalidations so that we can get the latest state and then perform
> > this check. I guess if we can do that then we can directly move the
> > restart logic to the end.
>
> IMO this shows the advantage of just waking up the worker. It doesn't
> change the apply worker's behavior besides making it more responsive.
>

But there doesn't appear to be any guarantee that the result for
AllTablesyncsReady() will change between the time it is invoked
earlier in the function and at the place you have it in the patch.
This is because the value of 'table_states_valid' may not have
changed. So, how is this supposed to work?

--
With Regards,
Amit Kapila.