Re: [HACKERS] Full page writes improvement, code update

From: Koichi Suzuki <suzuki(dot)koichi(at)oss(dot)ntt(dot)co(dot)jp>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, josh(at)agliodbs(dot)com, pgsql-hackers(at)postgresql(dot)org, pgsql-patches(at)postgresql(dot)org
Subject: Re: [HACKERS] Full page writes improvement, code update
Date: 2007-04-12 01:40:04
Message-ID: 461D8DF4.1070200@oss.ntt.co.jp
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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(dot)koichi(at)oss(dot)ntt(dot)co(dot)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

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