Skip site navigation (1) Skip section navigation (2)

Re: seq scan cache vs. index cache smackdown

From: Christopher Browne <cbbrowne(at)acm(dot)org>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: seq scan cache vs. index cache smackdown
Date: 2005-02-15 19:04:49
Message-ID: m3hdkdod9q.fsf@knuth.knuth.cbbrowne.com (view raw or flat)
Thread:
Lists: pgsql-performance
In the last exciting episode, merlin(dot)moncure(at)rcsonline(dot)com ("Merlin Moncure") wrote:
>> It seems inevitable that Postgres will eventually eliminate that
>> redundant layer of buffering. Since mmap is not workable, that
>> means using O_DIRECT to read table and index data.
>
> What about going the other way and simply letting the o/s do all the
> caching?  How bad (or good) would the performance really be?

I'm going to see about taking this story to OLS (Ottawa Linux
Symposium) in July and will see what hearing I can get.  There are
historically some commonalities in the way this situation is regarded,
in that there was _long_ opposition to the notion of having unbuffered
disk devices.

If there's more "story" that definitely needs to be taken, let me
know...
-- 
output = reverse("moc.enworbbc" "@" "enworbbc")
http://linuxdatabases.info/info/slony.html
Rules of  the Evil Overlord  #90. "I will  not design my  Main Control
Room  so  that  every  workstation  is facing  away  from  the  door."
<http://www.eviloverlord.com/>

In response to

pgsql-performance by date

Next:From: lcham02Date: 2005-02-15 19:15:55
Subject: disagreeing query planners
Previous:From: Magnus HaganderDate: 2005-02-15 18:41:26
Subject: Re: seq scan cache vs. index cache smackdown

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group