Re: The naive test for equality
Date: Wed, 03 Aug 2005 21:46:52 +0100
Message-ID: <42f12d41$0$14693$ed2619ec_at_ptn-nntp-reader02.plus.net>
Marshall Spight wrote:
>>>Sure. Specifically, it's an equivalence relation. Let's distinguish >>>between the equality relation specifically and equivalence relations >>>in general. Equality is a much simpler thing. >> >>Is it, though?
>
> I wasn't clear whether you were questioning my "it's an equivalence
> relation" or my "equality is [simple]."
I guess what I'm saying is that equality isn't really simpler than equivalence relations - they're kind of the same thing really.
>>So for the underlying relational engine to compare two values for >>equality, it can't in general stay in the physical layer; it has just >>jump up into the logical layer, do the comparison, and then jump back >>down to the physical layer again.
>
> I am unclear as to what you are saying here. The implementation only
> operates at the implementation level. The implementation implements
> the logical level, or "interface." I don't know what you mean
> by "jump up."
what I mean is that you have the relational part and the domain part with their separate physical implementations - but the only way they can talk to each other to establish equality is via their "logical" interfaces - so going up an abstraction level. As opposed to the "naive" way where the relational part can establish equality on its own (using bit representation) without needing the domain part at all. I'm not really saying anthing new here, just rehashing existing posts but what the hell, it might be useful for someone to see something from several angles!
Paul. Received on Wed Aug 03 2005 - 22:46:52 CEST