Re: Priorities for users or queries?

From: "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
To: Ron Mayer <rm_pg(at)cheapcomplexdevices(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: Priorities for users or queries?
Date: 2007-02-23 22:38:27
Message-ID: 20070223223826.GC11743@decibel.org
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On Fri, Feb 23, 2007 at 12:07:56PM -0800, Ron Mayer wrote:
> Jim Nasby wrote:
> > The problem with using simple OS priority settings is you leave yourself
> > wide open to priority inversion.
>
> Which is why you either
> (a) note that papers studying priority inversion on RDBMS's
> find that it's a non issue on many RDBMS workloads; and
> (except for real-time databases) you tend to still get
> at least partial benefits even in the face of priority
> inversions.
> or
> (b) use a scheduler in your OS that supports priority
> inheritance or other mechanisms to avoid priority
> inversion problems.
> If you want to use priority inheritance to avoid
> the priority inversion settings it appears versions
> of Linux, BSD, Windows, and Solaris at least give
> you the ability to do so.
>
> > There is already work being done on a queuing system; take a look at the
> > bizgres archives.
>
> Which is cool; but not quite the same as priorities.
>
> It seems to me that Bizgres and/or PostgreSQL would not
> want to re-implement OS features like schedulers.

Actually, I believe part of the discussion also involved how to handle
long-running workloads that you don't want to monopolize the machine.
--
Jim C. Nasby, Database Architect decibel(at)decibel(dot)org
Give your computer some brain candy! www.distributed.net Team #1828

Windows: "Where do you want to go today?"
Linux: "Where do you want to go tomorrow?"
FreeBSD: "Are you guys coming, or what?"

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