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Message-ID: <461D8DF4.1070200@oss.ntt.co.jp>
Date: Thu, 12 Apr 2007 10:40:04 +0900
From: Koichi Suzuki <suzuki.koichi@oss.ntt.co.jp>
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: Simon Riggs <simon@2ndquadrant.com>,  josh@agliodbs.com,
	pgsql-hackers@postgresql.org,  pgsql-patches@postgresql.org
Subject: Re: [HACKERS] Full page writes improvement, code update
References: <460886E8.6040907@oss.ntt.co.jp> <4609CAC3.7060008@oss.ntt.co.jp>
	<1175072848.4386.323.camel@silverbirch.site>
	<200703291145.28574.josh@agliodbs.com>
	<1175200117.4386.616.camel@silverbirch.site>
	<460C611E.6090800@oss.ntt.co.jp> <27693.1176226131@sss.pgh.pa.us>
	<461C3557.6040201@oss.ntt.co.jp> <6050.1176331703@sss.pgh.pa.us>
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The score below was taken based on 8.2 code, not 8.3 code.  So I don't
think the below measure is introduced only in 8.3 code.

Tom Lane wrote:
> Koichi Suzuki <suzuki.koichi@oss.ntt.co.jp> writes:
>> For more information, when checkpoint interval is one hour, the amount
>> of the archived log size was as follows:
>> cp:             3.1GB
>> gzip:           1.5GB
>> pg_compresslog: 0.3GB
> 
> The notion that 90% of the WAL could be backup blocks even at very long
> checkpoint intervals struck me as excessive, so I went looking for a
> reason, and I may have found one.  There has been a bug in CVS HEAD
> since Feb 8 causing every btree page split record to include a backup
> block whether needed or not.  If these numbers were taken with recent
> 8.3 code, please retest with current HEAD.
> 
> 			regards, tom lane
> 


-- 
Koichi Suzuki