-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Thu, 03 Apr 2008 20:29:18 -0400 Tom Lane <[EMAIL PROTECTED]> wrote:
> "Joshua D. Drake" <[EMAIL PROTECTED]> writes: > > Heikki Linnakangas <[EMAIL PROTECTED]> wrote: > >> Why is that useful? > > > For knowing how long checkpoints are taking. If they are taking too > > long you may need to adjust your bgwriter settings, and it is a > > serious drag to parse postgresql logs for this info. > > 1. To do anything useful along those lines, you would need to look at > a lot of checkpoints over time, which is what log_checkpoints is good > for. This patch only tells you about the latest, which isn't very > useful for making any good decisions about parameters. I would agree with this. We would need a history of checkpoints that didn't reset until we told it to. > > 2. If I read the patch correctly, half of the time what you'd be > seeing is the start time of the currently-active checkpoint and the > completion time of the prior checkpoint. I don't know what those > numbers are good for at all. IMO we should see start checkpoint, end checkpoint. As part of a single record. Other possibly interesting info would be how many logs were processed. > > 3. As of PG 8.3, the bgwriter tries very hard to make the elapsed time > of a checkpoint be just about checkpoint_timeout * > checkpoint_completion_target, regardless of load factors. So unless > your settings are completely broken, measuring the actual time isn't > going to tell you much. > You assume that people don't have broken settings. :) > In short: Heikki's question is on point. I didn't say it wasn't. I was just stating why a patch that does what was described is useful. I believe with changes it would still be useful. Having to go to log for a lot of this stuff is painful. Joshua D. Drake - -- The PostgreSQL Company since 1997: http://www.commandprompt.com/ PostgreSQL Community Conference: http://www.postgresqlconference.org/ United States PostgreSQL Association: http://www.postgresql.us/ Donate to the PostgreSQL Project: http://www.postgresql.org/about/donate -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFH9YETATb/zqfZUUQRAmiTAJ0Shc4rSIKRG5nabAv9RwW1MVi/BQCfUIiK Nb8qyBonAlNl/Agp/wCyvTU= =H8TF -----END PGP SIGNATURE----- -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches
