Date: Fri, 29 Aug 2008 07:08:52 -0400
From: Bill Moran <wmoran@collaborativefusion.com>
To: Greg Smith <gsmith@gregsmith.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: select on 22 GB table causes
	"An I/O error occured while sending to the backend." exception
Message-Id: <20080829070852.0000022f.wmoran@collaborativefusion.com>
In-Reply-To: <Pine.GSO.4.64.0808290039180.23621@westnet.com>
References: <BAY124-W57D3654AF1159CAF8EAC19F5660@phx.gbl>
	<82bpze3ou8.fsf@mid.bfk.de>
	<alpine.DEB.1.10.0808271436210.907@asgard.lang.hm>
	<alpine.DEB.1.10.0808281411220.4454@aragorn.flymine.org>
	<20080828095325.3c95f867.wmoran@collaborativefusion.com>
	<Pine.GSO.4.64.0808290039180.23621@westnet.com>
Organization: Collaborative Fusion
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

In response to Greg Smith <gsmith@gregsmith.com>:

> On Thu, 28 Aug 2008, Bill Moran wrote:
> 
> > In linux, it's possible to tell the OOM killer never to consider
> > certain processes for the axe, using /proc magic.  See this page:
> > http://linux-mm.org/OOM_Killer
> >
> > Perhaps this should be in the PostgreSQL docs somewhere?
> 
> The fact that 
> http://www.postgresql.org/docs/current/static/kernel-resources.html#AEN22218 
> tells you to flat-out turn off overcommit is the right conservative thing 
> to be in the documentation as I see it.  Sure, it's possible to keep it on 
> but disable the worst side-effect in some kernels (looks like 2.6.11+, so 
> no RHEL4 for example).  Trying to get into all in the manual is kind of 
> pushing what's appropriate for the PostgreSQL docs I think.

I don't know, Greg.  First off, the solution of making the postmaster
immune to the OOM killer seems better than disabling overcommit to me
anyway; and secondly, I don't understand why we should avoid making
the PG documentation as comprehensive as possible, which seems to be
what you are saying: "we shouldn't make the PG documentation too
comprehensive, because then it will get very big"

-- 
Bill Moran
Collaborative Fusion Inc.
http://people.collaborativefusion.com/~wmoran/

wmoran@collaborativefusion.com
Phone: 412-422-3463x4023