To: =?UTF-8?B?QWxleGlzIEzDqi1RdcO0Yw==?= <alq@datadoghq.com>
cc: pgsql-performance@postgresql.org
Subject: Re: Autovacuum running out of memory 
In-reply-to: 
 <CAAGz8TPX8O7e=r8ZsLEE2ABW6yv9gZreXqGeDydJgeQF2oCf_Q@mail.gmail.com>
References: 
 <CAAGz8TMPCzcMR0uo1Kjzi8uBgv3TpLRWVDOB4wHTdSASt=Q=1A@mail.gmail.com>
	<13854.1312996666@sss.pgh.pa.us>
	<CAAGz8TPX8O7e=r8ZsLEE2ABW6yv9gZreXqGeDydJgeQF2oCf_Q@mail.gmail.com>
Comments: In-reply-to =?UTF-8?B?QWxleGlzIEzDqi1RdcO0Yw==?= <alq@datadoghq.com>
	message dated "Wed, 10 Aug 2011 14:47:30 -0400"
Date: Wed, 10 Aug 2011 14:54:23 -0400
Message-ID: <15771.1313002463@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

=?UTF-8?B?QWxleGlzIEzDqi1RdcO0Yw==?= <alq@datadoghq.com> writes:
> On Wed, Aug 10, 2011 at 1:17 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> However, I find it a bit odd that you're getting this failure in what
>> appears to be a 64-bit build.  That means you're not running out of
>> address space, so you must actually be out of RAM+swap.  Does the
>> machine have only 4GB or so of RAM?  If so, that value for
>> shared_buffers is unrealistically large; it's not leaving enough RAM for
>> other purposes such as this.

> The box has little under 8GB (it's on EC2, a "m1.large" instance)
> There is no swap.

Hmph.  Is there other stuff being run on the same instance?  Are there a
whole lot of active PG processes?  Maybe Amazon isn't really giving you
a whole 8GB, or there are weird address space restrictions in the EC2
environment.  Anyway I think I'd suggest reducing shared_buffers to 1GB
or so.

>> Where did you get the above-quoted parameter settings, anyway?

> In turn they come from High-Performance Postgresql 9.0
> (http://www.postgresql.org/about/news.1249)

I'm sure even Greg wouldn't claim his methods are good to more than one
or two significant digits.

			regards, tom lane