From: S Arvind <arvindwill@gmail.com>
To: pgsql-performance@postgresql.org
Subject: Re: Running some query in low priority
Date: Thu, 5 Nov 2009 18:50:19 +0530
Message-ID: <abf9211d0911050520t72a5d6dfv877ced07077b11@mail.gmail.com> (raw)
In-Reply-To: <407d949e0911050332n5ef355c1y156dcd26aa28d222@mail.gmail.com>
References: <abf9211d0911050136g48739f0ft53b63f96cddf706@mail.gmail.com>
<2f4958ff0911050138n3f246b7ck6182cb702ac48e91@mail.gmail.com>
<407d949e0911050332n5ef355c1y156dcd26aa28d222@mail.gmail.com>
Thank Greg and Grzegorz,
As told i have large batch load to the postgres which i need to be
run in low priority. Is it really throttling the data will help to lower the
postgres workload for some queries?
-Arvind S
2009/11/5 Greg Stark <gsstark@mit.edu>
> 2009/11/5 Grzegorz Jaśkiewicz <gryzman@gmail.com>:
> >
> >
> > On Thu, Nov 5, 2009 at 9:36 AM, S Arvind <arvindwill@gmail.com> wrote:
> >>
> >> Hi Developers and Tuners,
> >> Is there any way to run some query in low priority and some
> query
> >> in higher priority in pg. The main reason for this is i need my main
> >> application(high priority) to be undisturbed by the sub application(low
> >> priority) which is running on same DB. Is there anyother good way to
> operate
> >> this?
> >
> > other than manually re-nicing back end, no.
>
> And unfortunately this doesn't really work very well. renicing only
> affects cpu priority and usually it's i/o priority you want to adjust.
> Even if you can adjust i/o priority per process on your operating
> system the database often does i/o work for one process in another
> process or has times when a process is waiting on another process to
> finish i/o. So lowering the i/o priority of the low priority process
> might not have the desired effect of speeding up other processes.
>
> Usually this isn't a problem unless you have a large batch load or
> something like that happening which consumes all available i/o. In
> that case you can sometimes reduce the i/o demand by just throttling
> the rate at which you send data to or read data from the server.
>
>
> --
> greg
>
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Subject: Re: Running some query in low priority
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