Re: Improve compression speeds in pg_lzcompress.c

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Takeshi Yamamuro <yamamuro.takeshi@lab.ntt.co.jp>, pgsql-hackers@postgresql.org
Date: 2013-01-07T21:19:36Z
Lists: pgsql-hackers
Robert Haas <robertmhaas@gmail.com> writes:
> 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.

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

			regards, tom lane