Re: log_duration is redundant, no?

On 9/8/06, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> If you are using an external tool, can't you just restrict what you
> display based on the logged duration?

It's not a matter of having too much information in our reports (the
more information I have, the happier I am :)). It's a matter of
slowing down too much the server with too much I/O.
We can afford to log every duration and queries slower than 500ms
nearly without any overhead. We can't afford to log every query, it
generates too much I/O - note that we tried to do it and it was really
too slow.
With the former configuration we log 1.2 GB/day, with the latter I
suspect it will be far more than 60 GB/day (I don't have the exact
number as we can't do it for real but queries slower than 500 ms
represents 1/100 of the total amount of queries).

Query logging is really a nice way to monitor the activity of a
PostgreSQL server and the overhead is not that high if logging I/O are
not too intensive.

--
Guillaume