Re: Getting time-dependent load statistics

On Fri, Feb 20, 2009 at 9:11 AM, Torsten Bronger
<bronger@physik.rwth-aachen.de> wrote:
> Hallöchen!
>
> Yesterday I ported a web app to PG.  Every 10 minutes, a cron job
> scanned the log files of MySQL and generated a plot showing the
> queries/sec for the last 24h.  (Admittedly queries/sec is not the
> holy grail of DB statistics.)
>
> But I still like to have something like this.  At the moment I just
> do the same with PG's log file, with
>
>    log_statement_stats = on
>
> But to generate these plots is costly (e.g. I don't need all the
> lines starting with !), and to interpret them is equally costly.  Do
> you have a suggestion for a better approach?

You can turn on log duration, which will just log the duration of
queries.  That's a handy little metric to have and every so often I
turn it on and chart average query run times etc with the actual
queries.  I also turn on logging long running queries of say 5 or 10
seconds or more.