Re: Occasional spike in query response time (jumps from 200ms to 45 seconds)

On Fri, Nov 8, 2013 at 5:25 AM, Robert Voinea <rvoinea(at)gmail(dot)com> wrote:

> Hi
>
> On Thursday 07 November 2013 06:37:57 bricklen wrote:
> > On Thu, Nov 7, 2013 at 2:44 AM, Robert Voinea <rvoinea(at)gmail(dot)com> wrote:
> > > Could you give me some hints on what to look for?
> > > What might be causing this behavior?
> >
> > Possibly checkpointing is the problem? Is "log_checkpoints" enabled in
> your
> > postgresql.conf? What is "checkpoint_completion_target" set to?
>
> The parameters are commented out, so they are at their default values.
>
> Thank you for replying.
> I'll investigate this further to see if this is the problem.
>

Checkpointing may or may not be the problem, but changing log_checkpoints =
on and checkpoint_completion_target = 0.8 would both be useful things to
do. The former to help in your investigation, the latter, known as
"checkpoint smoothing" might help alleviate the problem if it is indeed
related to checkpointing.