From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Thom Brown <thom(at)linux(dot)com> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql: Document random page cost is only 4x seqeuntial, and not 40x. |
Date: | 2012-02-14 22:46:18 |
Message-ID: | 20120214224618.GC3424@momjian.us |
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Lists: | pgsql-committers |
On Tue, Feb 14, 2012 at 10:44:08PM +0000, Thom Brown wrote:
> On 14 February 2012 21:55, Bruce Momjian <bruce(at)momjian(dot)us> wrote:
> > Document random page cost is only 4x seqeuntial, and not 40x.
> >
> > Branch
> > ------
> > master
> >
> > Details
> > -------
> > http://git.postgresql.org/pg/commitdiff/c1d9df4fa227781b31be44a5a3024865a7f48049
> >
> > Modified Files
> > --------------
> > doc/src/sgml/config.sgml | 20 ++++++++++++++++++++
> > 1 files changed, 20 insertions(+), 0 deletions(-)
>
> This change does say that it is 40 times slower:
>
> "The default value can be thought of as modeling random access as 40
> times slower than sequential..."
I meant to say that it documents why we have a default of 4x, not 40x.
(In fact, real world, it is probably 100x.)
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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