Re: Is Recovery actually paused?

On Wed, Feb 10, 2021 at 8:19 AM Kyotaro Horiguchi
<horikyota(dot)ntt(at)gmail(dot)com> wrote:
>
> At Tue, 9 Feb 2021 12:27:21 +0530, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote in
> > What I meant was that if we were to add waiting logic inside
> > pg_wal_replay_pause, we should also have a timeout with some default
> > value, to avoid pg_wal_replay_pause waiting forever in the waiting
> > loop. Within that timeout, if the recovery isn't paused,
> > pg_wal_replay_pause will return probably a warning and a false(this
> > requires us to change the return value of the existing
> > pg_wal_replay_pause)?
>
> I thought that rm_redo finishes shortly unless any trouble
> happens. But on second thought, I found that I forgot a case of a
> recovery-conflict. So as you pointed out, pg_wal_replay_pause() needs
> a flag 'wait' to wait for a pause established. And the flag can be
> turned into "timeout".
>
> # And the prevous verision had another silly bug.
>
> > To avoid changing the existing API and return type, a new function
> > pg_get_wal_replay_pause_state is introduced.
>
> I mentioned about IN parameters, not OUTs. IN parameters can be
> optional to accept existing usage. pg_wal_replay_pause() is changed
> that way in the attached.
>
> If all of you still disagree with my proposal, I withdraw it.

I don't find any problem with this approach as well, but I personally
feel that the other approach where we don't wait in any API and just
return the recovery pause state is much simpler and more flexible. So
I will make the pending changes in that patch and let's see what are
the other opinion and based on that we can conclude. Thanks for the
patch.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com