Re: Checkpoints and slow queries

On 28.4.2014 22:54, Jeff Janes wrote:
> On Mon, Apr 28, 2014 at 1:41 PM, Tomas Vondra <tv(at)fuzzy(dot)cz
> There's certainly something fishy, because although this is the supposed
> configuration:
>
> checkpoint_segments = 250
> checkpoint_timeout = 1h
> checkpoint_completion_target = 0.9
>
> the checkpoint logs typically finish in much shorter periods of time.
>
> That doesn't look fishy to me. The checkpointer will not take more than
> one nap between buffers, so it will always write at least 10 buffers per
> second (of napping time) even if that means it finishes early. Which
> seems to be the case here--the length of the write cycle seems to be
> about one tenth the number of buffers written.

Oh, makes sense I guess. Apparently I'm tuning this only on systems
doing a lot of I/O, so this behaviour somehow escaped me.

Tomas