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Re: Escaping the ARC patent

From: "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>,pgsql-hackers(at)postgresql(dot)org
Subject: Re: Escaping the ARC patent
Date: 2005-02-04 21:35:59
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Lists: pgsql-hackers
On Fri, Feb 04, 2005 at 11:27:40AM -0500, Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > So are you saying you are making T1, T2, B1, and B2 a fixed percentage
> > of the buffer cache rather than making them adjust over time?
> B2 goes away entirely (if we keep four lists we violate claim 45) and
> the other lists become fixed length, yes.
> We could also contemplate making them variable length according to some
> other set of rules than ARC's, but then you get into having to parse the
> other sixty-odd claims of the patent and decide what is a "different
> enough" rule.
> At the moment I'm not seeing evidence that a variable policy beats a
> fixed policy anyway.  Unless someone comes up with a benchmark showing a
> substantial advantage for ARC over 2Q, I think we should just declare
> victory over this problem.  We have plenty of other tasks on our plates.

I think it would be useful to have a means to adjust the queue sizes
dynamically from a database connection. If the optimum queue sizes
depend on the workload this would allow things like batch processes to
tweak the queue sizes for better performance when they're running. It
would also facilitate performing the testing you mention.
Jim C. Nasby, Database Consultant               decibel(at)decibel(dot)org 
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