Re: Autovacuum running out of memory

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alexis Lê-Quôc <alq(at)datadoghq(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Autovacuum running out of memory
Date: 2011-08-10 18:54:23
Message-ID: 15771.1313002463@sss.pgh.pa.us
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=?UTF-8?B?QWxleGlzIEzDqi1RdcO0Yw==?= <alq(at)datadoghq(dot)com> writes:
> On Wed, Aug 10, 2011 at 1:17 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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

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