Re: archive_timeout, checkpoint_timeout

On Wed, 30 Jul 2008, Rob Adams wrote:

> Could someone please explain in layman's terms the implications of using a
> checkpoint_timeout of ~1min as well? Is it a bad idea?

Lowering checkpoint_timeout makes checkpoints more frequent, causing the
database to go through WAL segments (at 16MB each) more often. Since
those get reused as needed, the peak disk usage footprint of your server
shouldn't be any higher. However, churning through that extra disk space
and doing the checkpoint bookkeeping so often can cause your server
performance to suffer a bit during heavy activity. Make sure to watch
what the server looks like under peak load, you may discover that lowering
these timeouts so much can cause it to have more trouble keeping up.
That's the usual trade-off here; the more often you want to ship useful
copies of things to another server, the more processing and particularly
disk overhead goes along with that.

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