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Date: Thu, 21 Apr 2011 13:08:00 -0700
Message-ID: <BANLkTimog78KjkuRjsYBJA8uDeLw4ajFFA@mail.gmail.com>
Subject: Re: oom_killer
From: Tory M Blue <tmblue@gmail.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Claudio Freire <klaussfreire@gmail.com>, pgsql-performance@postgresql.org
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On Thu, Apr 21, 2011 at 1:04 PM, Scott Marlowe <scott.marlowe@gmail.com> wr=
ote:
> On Thu, Apr 21, 2011 at 11:15 AM, Tory M Blue <tmblue@gmail.com> wrote:
>
>> While I don't mind the occasional slap of reality. This configuration
>> has run for 4+ years. It's possible that as many other components each
>> fedora release is worse then the priors.
>
> How many of those 300 max connections do you generally use? =A0If you've
> always used a handful, or you've used more but they weren't memory
> hungry then you've been lucky.

max of 45

> work_mem is how much memory postgresql can allocate PER sort or hash
> type operation. =A0Each connection can do that more than once. =A0A
> complex query can do it dozens of times. =A0Can you see that going from
> 20 to 200 connections and increasing complexity can result in memory
> usage going from a few megabytes to something like 200 connections *
> 100Megabytes per sort * 3 sorts =3D 60Gigabytes.
>
>> The Os has changed 170 days ago from fc6 to f12, but the postgres
>> configuration has been the same, and umm no way it can operate, is so
>> black and white, especially when it has ran performed well with a
>> decent sized data set for over 4 years.
>
> Just because you've been walking around with a gun pointing at your
> head without it going off does not mean walking around with a gun
> pointing at your head is a good idea.


Yes that is what I gathered. It's good information and I'm always open
to a smack if I learn something, which in this case I did.

We were already working on moving to 64bit, but again the oom_killer
popping up without the system even attempting to use swap is what has
caused me some pause.

Thanks again
Tory