Re: A few new options for CHECKPOINT

On Wed, Nov 25, 2020 at 01:07:47AM +0000, tsunakawa.takay@fujitsu.com wrote:
> From: Bossart, Nathan <bossartn@amazon.com>
>> It may be useful for backups taken with the "consistent snapshot"
>> approach.  As noted in the documentation [0], running CHECKPOINT
>> before taking the snapshot can reduce recovery time.  However, users
>> might wish to avoid the IO spike caused by an immediate checkpoint.
>>
>> [0] https://www.postgresql.org/docs/devel/backup-file.html
>
> Ah, understood.  I agree that the slow or spread manual checkpoint is good to have.

I can see the use case for IMMEDIATE, but I fail to see the use cases
for WAIT and FORCE.  CHECKPOINT_FORCE is internally implied for the
end-of-recovery and shutdown checkpoints.  WAIT could be a dangerous
thing if disabled, as clients could pile up requests to the
checkpointer for no real purpose.
--
Michael