Re: Monitoring postgres slowdowns

On Monday 17 Jun 2002 11:12 pm, Steve Bacon wrote:
> Hello,
>   is there any way to "look under the hood" when slowdowns occur? We
> have a tomcat / postgres site with each app having it's own server.
> The db machine is a dual CPU / RAID 5 / 2GB RAM box running RedHat
> Linux 7.1 and Postgres 7.1.3

> We seem to have daily slowdowns, and the only tools I know of are top
> and ps

Try looking at vmstat and iostat to see some more info.  What does vmstat say
is happening on the DB server when this slowdown occurs?

> Out user load isn't very heavy (max of 200 users), yet occasionally
> things just crawl. Looking at the tomcat machine shows most memory
> free low CPU usage, so all signs point to the DB machine - but how to
> tell if something's wrong / what exactly it is doing at the moment?

Logging queries might help - it could be locks on competing updates. I take it
your application logs don't show any obvious patterns.

- Richard Huxton