Re: Principle of Orthogonal Design

On Feb 3, 1:02 pm, Jan Hidders <hidd..._at_gmail.com> wrote:
> On 2 feb, 13:50, mAsterdam <mAster..._at_vrijdag.org> wrote:
> [huge snips]
> > I think 'named perspective' was just an unfamiliar
> > label to a familiar concept.
>
> Yes. The named perspective is the usual perspective where tuples are
> defined as functions from attribute names to domain values, and the
> unnamed perspective is where they are defined as sequences. The latter
> is sometimes preferred in theoretical work because it is closer to how
> logicians formalize things (in P(x,y,z) there are no attribute names,
> just the 1st, 2nd and 3rd place in the predicate) and it simplifies
> notation sometimes.

I would echo that this is an important distinction to be aware of. I personally favour the named perspective for a couple of reasons: first, when Codd introduced attribute names there was an implicit shift from a traditional ordered mathematical tuple, to a "tuple" being viewed as an (unordered) partial function. Second, without the attribute name a datum is in fact no datum at all, but rather simply noise. Attributes are as much a component of the data under consideration as the value they are mapped to. Hence, to disregard (or rather externalize) attributes from a mathematical model of data seems rather imprudent. Received on Tue Feb 05 2008 - 13:55:37 CET