Re: Queries becoming slow under heavy load

From: Kevin Grittner
Subject: Re: Queries becoming slow under heavy load
Date: ,
Msg-id: 4D3EF6680200002500039CA0@gw.wicourts.gov
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In response to: Queries becoming slow under heavy load  ("Anne Rosset")
List: pgsql-performance

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Queries becoming slow under heavy load  ("Anne Rosset", )
 Re: Queries becoming slow under heavy load  (Andy Colson, )
 Re: Queries becoming slow under heavy load  ("Kevin Grittner", )
 Re: Queries becoming slow under heavy load  ("Ing. Marcos Ortiz Valmaseda", )
 Re: Queries becoming slow under heavy load  (Ivan Voras, )
  Re: Queries becoming slow under heavy load  ("mark", )
 FW: Queries becoming slow under heavy load  ("Anne Rosset", )
  Re: FW: Queries becoming slow under heavy load  (Shaun Thomas, )
   Re: FW: Queries becoming slow under heavy load  (Scott Marlowe, )
  Re: FW: Queries becoming slow under heavy load  (Scott Marlowe, )
   Re: FW: Queries becoming slow under heavy load  ("Anne Rosset", )
    Re: FW: Queries becoming slow under heavy load  (Shaun Thomas, )
     Re: FW: Queries becoming slow under heavy load  (Mladen Gogala, )
     Re: FW: Queries becoming slow under heavy load  ("Anne Rosset", )
      Re: FW: Queries becoming slow under heavy load  (Scott Marlowe, )

"Anne Rosset" <> 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


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Subject: Re: Queries becoming slow under heavy load