Stephen Frost <sfrost@snowman.net> writes:
> * Robert Haas (robertmhaas@gmail.com) wrote:
>> Yeah - I think we had better reserve the fourth bit pattern for
>> something extensible e.g. another byte or several to specify the
>> actual method, so that we don't have a hard limit of 4 methods. But
>> even with such a system, the first 3 methods will always and forever
>> be privileged over all others, so we'd better not make the mistake of
>> adding something silly as our third algorithm.
> In such a situation, would they really end up being properly distinct
> when it comes to what our users see..? I wouldn't really think so.
It should be transparent to users, sure, but the point is that the
first three methods will have a storage space advantage over others.
Plus we'd have to do some actual work to create that extension mechanism.
I'm with Robert in that I do not see any urgency to add another method.
The fact that Stephen is already questioning whether LZ4 should have
been added first is not making me any more eager to jump here.
Compression methods come, and they go, and we do not serve anyone's
interest by being early adopters.
regards, tom lane