Re: [PATCHES] Load distributed checkpoint patch

From: "ITAGAKI Takahiro" <itagaki.takahiro@oss.ntt.co.jp>
> Bruce Momjian <bruce@momjian.us> wrote:
>> Do you use the same delay autovacuum uses?
>
> What do you mean 'the same delay'? Autovacuum does VACUUM, not
CHECKPOINT.
> If you think cost-based-delay, I think we cannot use it here. It's
hard to
> estimate how much checkpoints delay by cost-based sleeping, but we
should
> finish asynchronous checkpoints by the start of next checkpoint. So
I gave
> priority to punctuality over load smoothing.

I consider that smoothing the load (more meaningfully, response time)
has higher priority over checkpoint punctuality in a practical sense,
because the users of a system benefit from good steady response and
give good reputation to the system.  If the checkpoint processing is
not punctual, crash recovery would take longer time.  But which would
you give higher priority, the unlikely event (=crash of the system) or
likely event (=peek hours of the system)?  I believe the latter should
be regarded.  The system can write dirty buffers after the peek hours
pass.  User experience should be taken much case of.