Re: Is Recovery actually paused?

On Wed, Oct 21, 2020 at 7:16 AM Dilip Kumar  wrote:
> I have noticed one more issue, the problem is that if the recovery
> process is currently not processing any WAL and just waiting for the
> WAL to become available then the pg_is_wal_replay_paused will be stuck
> forever.  Having said that there is the same problem even if we design
> the new interface which checks whether the recovery is actually paused
> or not because until the recovery process gets the next wal it will
> not check whether the recovery pause is requested or not so the actual
> recovery paused flag will never be set.
>
> One idea could be, if the recovery process is waiting for WAL and a
> recovery pause is requested then we can assume that the recovery is
> paused because before processing the next wal it will always check
> whether the recovery pause is requested or not.

That seems fine, because the user's question is presumably whether the
pause has taken effect so that no more records will be replayed
barring an un-paused.

However, it might be better to implement this by having the system
absorb the pause immediately when it's in this state, rather than
trying to detect this state and treat it specially.

-- 
Robert Haas
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