Message-ID: <475D6F09.9000007@commandprompt.com>
Date: Mon, 10 Dec 2007 08:53:29 -0800
From: "Joshua D. Drake" <jd@commandprompt.com>
Organization: Command Prompt, Inc.
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To: Listaccount <lst_hoe01@kwsoft.de>
CC: pgsql-docs@postgresql.org
Subject: Re: [ADMIN] Dangerous hint in the PostgreSQL manual
References: <20071210162612.a9y113hzjkookooc@webmail.kwsoft.de>
In-Reply-To: <20071210162612.a9y113hzjkookooc@webmail.kwsoft.de>
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Listaccount wrote:
> Hello
> 
> I have been trapped by the advice from the manual to use "sysctl -w 
> vm.overcommit_memory=2" when using Linux (see 16.4.3. Linux Memory 
> Overcommit). This value should only be used when PostgreSQL is the only 
> Application running on the machine in question. It should be checked 
> against the values "CommitLimit" and "Committed_AS" in /proc/meminfo on 
> a longer running system. If "Committed_AS" reaches or come close to 
> "CommitLimit" one should not set overcommit_memory=2 (see
> http://www.redhat.com/archives/rhl-devel-list/2005-February/msg00738.html). 
> I think it should be included in the manual as a warning because with 
> this setting the machine in question may get trouble with "fork failed" 
> even if the standard system tools report a lot of free memory causing 
> confusion to the admins.


This discussion belongs on -docs... moving.


Joshua D. Drake

> 
> Regards
> 
> Andreas
> 
> 
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
>       choose an index scan if your joining column's datatypes do not
>       match
>