| From: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
|---|---|
| To: | "Greg Smith" <greg(at)2ndquadrant(dot)com>, "Richard Neill" <rn214(at)cam(dot)ac(dot)uk> |
| Cc: | "Heikki Linnakangas" <heikki(dot)linnakangas(at)enterprisedb(dot)com>, "PostgreSQL Performance" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Checkpoint spikes |
| Date: | 2009-12-08 15:05:04 |
| Message-ID: | 4B1E16C0020000250002D1D9@gw.wicourts.gov |
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| Lists: | pgsql-performance |
Richard Neill <rn214(at)cam(dot)ac(dot)uk> wrote:
> So far, I've set checkpoint_segments to 128, timeout to 10min, and
> completion_target to 0.8. This helps, but not as much as I'd
> hoped.
>
> But I haven't touched any of the other WAL or BG Writer settings.
>
> Where should I look next?
On our web servers, where we had similar issues, we seem to be doing
OK using:
bgwriter_lru_maxpages = 1000
bgwriter_lru_multiplier = 4.0
The other thing which can help this problem is keeping
shared_buffers smaller than most people recommend. We use 512MB on
our larger web server and 256MB on other servers. (Be sure to test
with your actual load, as this might or might not degrade overall
performance.)
-Kevin
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