Re: Compression and on-disk sorting

Martijn van Oosterhout <kleptog@svana.org> writes:
> Clever idea, pity we can't use it (what's the bet it's patented?). I'd
> wager anything beyond simple compression is patented by someone.

You're in for a rude awakening: even "simple compression" is anything
but simple.  As I said, it's a minefield of patents.  I recall reading a
very long statement by one of the zlib developers (Jean-loup Gailly, I
think) explaining exactly how they had threaded their way through that
minefield, and why they were different enough from half-a-dozen
similar-looking patented methods to not infringe any of them.

I feel fairly confident that zlib is patent-free, first because they did
their homework and second because they've now been out there and highly
visible for a good long time without getting sued.  I've got no such
confidence in any other random algorithm you might choose --- in fact,
I'm not at all sure that pg_lzcompress.c is safe.  If we were
aggressively trying to avoid patent risks we might well consider
dropping pg_lzcompress.c and using zlib exclusively.
        regards, tom lane