Re: Improve compression speeds in pg_lzcompress.c

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Takeshi Yamamuro <yamamuro.takeshi@lab.ntt.co.jp>, pgsql-hackers@postgresql.org
Date: 2013-01-07T21:07:51Z
Lists: pgsql-hackers
On Mon, Jan 7, 2013 at 11:16 AM, Tom Lane <tgl@sss.pgh.pa.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.

I'm not sure how general that result is.

-- 
Robert Haas
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