Re: "nice"/low priority Query

From: Tom Lane
Subject: Re: "nice"/low priority Query
Date: ,
Msg-id: 11484.1122999570@sss.pgh.pa.us
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In response to: "nice"/low priority Query  (Tobias Brox)
Responses: Re: "nice"/low priority Query  (Richard Huxton)
Re: "nice"/low priority Query  ("Jim C. Nasby")
List: pgsql-performance

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"nice"/low priority Query  (Tobias Brox, )
 Re: "nice"/low priority Query  (Tom Lane, )
  Re: "nice"/low priority Query  (Richard Huxton, )
  Re: "nice"/low priority Query  ("Jim C. Nasby", )
   Re: "nice"/low priority Query  (Neil Conway, )
 Re: "nice"/low priority Query  (Tobias Brox, )
  Re: "nice"/low priority Query  (Richard Huxton, )

Tobias Brox <> writes:
> Is there any ways to give postgresql a hint that a
> particular SQL call should be run at lower priority?  Since every db
> connection has a pid, I can manually run "renice" to scheduele it by the OS
> - but of course I can't do it manually all the time.

And it won't help you anyway, because renice only affects CPU priority
not I/O scheduling ... which, by your description, is the real problem.

I think the only thing that's likely to help much is trying to arrange
that the "simple" queries only need to touch pages that are already in
memory.  Some playing around with shared_buffer sizing might help.
Also, if you're not on PG 8.0.*, an update might help.

            regards, tom lane


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From: Tobias Brox
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Subject: Re: "nice"/low priority Query