Re: Improve compression speeds in pg_lzcompress.c - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Improve compression speeds in pg_lzcompress.c
Date
Msg-id 11201.1357575367@sss.pgh.pa.us
Whole thread Raw
In response to Improve compression speeds in pg_lzcompress.c  (Takeshi Yamamuro <yamamuro.takeshi@lab.ntt.co.jp>)
Responses Re: Improve compression speeds in pg_lzcompress.c
Re: Improve compression speeds in pg_lzcompress.c
List pgsql-hackers
Takeshi Yamamuro <yamamuro.takeshi@lab.ntt.co.jp> writes:
> The attached is a patch to improve compression speeds with loss of
> compression ratios in backend/utils/adt/pg_lzcompress.c.

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.

Another thing to keep in mind is that the compression area in general
is a minefield of patents.  We're fairly confident that pg_lzcompress
as-is doesn't fall foul of any, but any significant change there would
probably require more research.
        regards, tom lane



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