Re: Why we are going to have to go DirectIO

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Claudio Freire <klaussfreire(at)gmail(dot)com>, Tatsuo Ishii <ishii(at)postgresql(dot)org>, KONDO Mitsumasa <kondo(dot)mitsumasa(at)lab(dot)ntt(dot)co(dot)jp>, Magnus Hagander <magnus(at)hagander(dot)net>, Josh Berkus <josh(at)agliodbs(dot)com>, Stefan Kaltenbrunner <stefan(at)kaltenbrunner(dot)cc>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Why we are going to have to go DirectIO
Date: 2013-12-11 01:25:04
Message-ID: 15481.1386725104@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> On Tue, Dec 3, 2013 at 11:39 PM, Claudio Freire <klaussfreire(at)gmail(dot)com>wrote:
>> Problem is, Postgres relies on a working kernel cache for checkpoints.
>> Checkpoint logic would have to be heavily reworked to account for an
>> impaired kernel cache.

> I don't think it would need anything more than a sorted checkpoint.

Nonsense. We don't have access to the physical-disk-layout information
needed to do reasonable sorting; to say nothing of doing something
intelligent in a multi-spindle environment, or whenever any other I/O
is going on concurrently.

regards, tom lane

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Sergey E. Koposov 2013-12-11 01:27:04 Re: ANALYZE sampling is too good
Previous Message Claudio Freire 2013-12-11 01:09:19 Re: Why we are going to have to go DirectIO