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Re: Improve compression speeds in pg_lzcompress.c

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Takeshi Yamamuro <yamamuro(dot)takeshi(at)lab(dot)ntt(dot)co(dot)jp>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Improve compression speeds in pg_lzcompress.c
Date: 2013-01-07 21:19:36
Message-ID: 17407.1357593576@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Mon, Jan 7, 2013 at 11:16 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Why would that be a good tradeoff to make?  Larger stored values require
>> more I/O, which is likely to swamp any CPU savings in the compression
>> step.  Not to mention that a value once written may be read many times,
>> so the extra I/O cost could be multiplied many times over later on.

> I agree with this analysis, but I note that the test results show it
> actually improving things along both parameters.

Hm ... one of us is reading those results backwards, then.

			regards, tom lane


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Subject: Re: Improve compression speeds in pg_lzcompress.c
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