Re: checkpoint_timeout

On Wed, Oct 8, 2008 at 12:08 PM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
>
> If the problem is checkpoints (which seems likely but far from a sure
> thing based on the information provided), aggressive background writer
> setting might be your best bet under 8.2.X. To solve similar problems
> we had to go to the following, although many on these lists feel that
> settings this aggressive are rarely needed, so use at your own risk.
>
> #bgwriter_delay = 200ms
> bgwriter_lru_percent = 20.0
> bgwriter_lru_maxpages = 200
> bgwriter_all_percent = 10.0
> bgwriter_all_maxpages = 600

I've tuned an 8.2 server with settings similar to this, and it made a
world of difference on smoothing out performance. Note that bgwriter
tends to use cpu and memory bandwidth up, so avoid going crazy on it.

> Even better would be to go to the latest revision of the 8.3 release,
> which at this writing is 8.3.4. In that release PostgreSQL spreads
> out the work of a checkpoint to minimize this problem.

Seconded. A lot of hard work went into making the bgwriter much
easier to adjust, and much less likely to even need adjusting in 8.3.