Re: Queries becoming slow under heavy load

"Anne Rosset" <arosset@collab.net> wrote:

> We are running some performances tests.  With a lot of concurrent
> access, queries get very slow. When there is no load, those
> queries run fast.

What's "a lot"?

> We kind of see a trend about these queries:  it seems like the
> ones that become very slow have an ORDER BY or MAX in them.

Without knowing the PostgreSQL version or more details about the
queries, I would only be guessing at the cause.

> It seems to me that we should try increasing shared_buffers. But
> do you have any other suggestions? Or do you see anything wrong in
> our config?

I don't think you showed us your whole PostgreSQL configuration, and
the format was hard to read -- it's best to show the contents of
your postgresql.conf file, minus comments.

If you read this page and re-post we can probably be more helpful:

http://wiki.postgresql.org/wiki/SlowQueryQuestions

-Kevin