From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Kris Jurka <books(at)ejurka(dot)com> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql: TODO item not needed anymore now that the buffer cache is |
Date: | 2007-06-02 11:28:36 |
Message-ID: | 200706021128.l52BSaS19770@momjian.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-committers |
Kris Jurka wrote:
>
>
> On Fri, 1 Jun 2007, Bruce Momjian wrote:
>
> > Log Message:
> > -----------
> > TODO item not needed anymore now that the buffer cache is
> > scan-resistant:
> >
> > <
> > < * Allow free-behind capability for large sequential scans, perhaps using
> > < posix_fadvise()
> > <
> > < Posix_fadvise() can control both sequential/random file caching and
> > < free-behind behavior, but it is unclear how the setting affects other
> > < backends that also have the file open, and the feature is not supported
> > < on all operating systems.
> >
>
> This todo item is about telling the OS cache that we don't want these
> buffers kept around, not about pg's own buffer cache. So I think it's
> still valid.
Agreed, re-added, and clarified it is for the kernel cache:
* Allow free-behind capability for large sequential scans to avoid
kernel cache spoiling
Posix_fadvise() can control both sequential/random file caching and
free-behind behavior, but it is unclear how the setting affects other
backends that also have the file open, and the feature is not supported
on all operating systems.
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com
+ If your life is a hard drive, Christ can be your backup. +
From | Date | Subject | |
---|---|---|---|
Next Message | Neil Conway | 2007-06-02 15:15:30 | pgsql: Remove incorrect semicolon in example. |
Previous Message | Bruce Momjian | 2007-06-02 11:28:01 | pgsql: Re-add TODO and clarify it is for the kernel cache: < * Allow |