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Message-ID: <46486705.3000507@enterprisedb.com>
Date: Mon, 14 May 2007 14:41:25 +0100
From: Heikki Linnakangas <heikki@enterprisedb.com>
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To: Greg Smith <gsmith@gregsmith.com>
CC: pgsql-patches@postgresql.org
Subject: Re: Automatic adjustment of bgwriter_lru_maxpages
References: <461E108D.6080709@enterprisedb.com>
	<Pine.GSO.4.64.0705121926420.9615@westnet.com>
	<20070514174531.71E0.ITAGAKI.TAKAHIRO@oss.ntt.co.jp>
	<Pine.GSO.4.64.0705140926470.9478@westnet.com>
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Greg Smith wrote:
> On Mon, 14 May 2007, ITAGAKI Takahiro wrote:
> 
>> BTW, your patch will cut LRU writes short, but will not encourage to
>> do more works. So should set more aggressive values to 
>> bgwriter_lru_percent
>> and bgwriter_lru_maxpages as defaults?
> 
> Setting a bigger default maximum is one possibility I was thinking 
> about. Since the whole background writer setup is kind of complicated, 
> the other thing I was working on is writing a guide on how to use the 
> new pg_stat_bgwriter information to figure out if you need to increase 
> bgwriter_[all|lru]_pages (and the other parameters too).  It makes it 
> much easier to write that if you can say "You can safely set 
> bgwriter_lru_maxpages high because it only writes what it needs to based 
> on your usage".

If it's safe to set it high, let's default it to infinity.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com