Re: pg_get_wal_replay_pause_state() should not return 'paused' while a promotion is ongoing.

On 2021/05/18 15:46, Michael Paquier wrote:
> On Tue, May 18, 2021 at 12:48:38PM +0900, Fujii Masao wrote:
>> Currently a promotion causes all available WAL to be replayed before
>> a standby becomes a primary whether it was in paused state or not.
>> OTOH, something like immediate promotion (i.e., standby becomes
>> a primary without replaying outstanding WAL) might be useful for
>> some cases. I don't object to that.
>
> Sounds like a "promotion immediate" mode. It does not sound difficult
> nor expensive to add a small test for that in one of the existing
> recovery tests triggerring a promotion. Could you add one based on
> pg_get_wal_replay_pause_state()?

You're thinking to add the test like the following?
#1. Pause the recovery
#2. Confirm that pg_get_wal_replay_pause_state() returns 'paused'
#3. Trigger standby promotion
#4. Confirm that pg_get_wal_replay_pause_state() returns 'not paused'

It seems not easy to do the test #4 stably because
pg_get_wal_replay_pause_state() needs to be executed
before the promotion finishes.

Regards,

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION