Re: Improve compression speeds in pg_lzcompress.c

Takeshi Yamamuro <yamamuro(dot)takeshi(at)lab(dot)ntt(dot)co(dot)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