Re: [HACKERS] Full page writes improvement, code update - Mailing list pgsql-patches

From Koichi Suzuki
Subject Re: [HACKERS] Full page writes improvement, code update
Date
Msg-id 461D8DF4.1070200@oss.ntt.co.jp
Whole thread Raw
In response to Re: [HACKERS] Full page writes improvement, code update  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-patches
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

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