Re: Compression and on-disk sorting

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Martijn van Oosterhout <kleptog(at)svana(dot)org>
Cc: Albe Laurenz <all(at)adv(dot)magwien(dot)gv(dot)at>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Compression and on-disk sorting
Date: 2006-05-17 14:25:01
Message-ID: 19684.1147875901@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Martijn van Oosterhout <kleptog(at)svana(dot)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

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Andrew Dunstan 2006-05-17 14:27:15 Re: PL/pgSQL 'i = i + 1' Syntax
Previous Message Stephan Szabo 2006-05-17 14:19:45 Foreign key column reference ordering and information_schema