Re: PostgreSQL 8.0 occasionally slow down

Hi Greg.

2007/6/28, Greg Smith <gsmith(at)gregsmith(dot)com>:
>
> On Thu, 28 Jun 2007, Ho Fat Tsang wrote:
>
> > I have tuned the checkpoint_timeout to 30 second which is ten times less
> > than default and the issue is still reproduced.

Doing a checkpoint every 30 seconds is crazy; no wonder your system is
> pausing so much. Put the timeout back to the default. What you should do
> here is edit your config file and set checkpoint_warning to its maximum of
> 3600. After that, take a look at the log files; you'll then get a warning
> message every time a checkpoint happens. If those line up with when
> you're getting the slowdowns, then at least you'll have narrowed the cause
> of your problem, and you can get some advice here on how to make the
> overhead of checkpoints less painful.
>
> The hint it will give is probably the first thing to try: increase
> checkpoint_segments from the default to something much larger (if it's at
> 3 now, try 10 instead to start), and see if the problem stops happening as
> frequently. Your problem looks exactly like a pause at every checkpoint,
> and I'm not sure what Richard was thinking when he suggested having them
> more often would improve things.

Yes, Thank you for your suggestion. i have found that the slowdown time does
not align to checkpoint after i turned on the warning. The issue is related
what Richard has been mentioned - Something outsides PG doing many write
operations to pages.

--
> * Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD
>
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