To: Bruce Momjian <bruce@momjian.us>
Cc: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>,
	Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: Visibility map, partial vacuums
In-Reply-To: <200901150055.n0F0tLK27057@momjian.us> (Bruce Momjian's message
	of "Wed\, 14 Jan 2009 19\:55\:21 -0500 \(EST\)")
User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux)
References: <200901150055.n0F0tLK27057@momjian.us>
From: Gregory Stark <stark@enterprisedb.com>
Organization: EnterpriseDB
Date: Thu, 15 Jan 2009 01:40:33 +0000
Message-ID: <87wscxfisu.fsf@oxford.xeocode.com>
MIME-Version: 1.0
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Bruce Momjian <bruce@momjian.us> writes:

> Would someone tell me why 'autovacuum_freeze_max_age' defaults to 200M
> when our wraparound limit is around 2B?

I suggested raising it dramatically in the post you quote and Heikki pointed
it controls the maximum amount of space the clog will take. Raising it to,
say, 800M will mean up to 200MB of space which might be kind of annoying for a
small database.

It would be nice if we could ensure the clog got trimmed frequently enough on
small databases that we could raise the max_age. It's really annoying to see
all these vacuums running 10x more often than necessary.

The rest of the thread is visible at the bottom of:

http://article.gmane.org/gmane.comp.db.postgresql.devel.general/107525

> Also, is anything being done about the concern about 'vacuum storm'
> explained below?

I'm interested too.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com
  Ask me about EnterpriseDB's PostGIS support!