Re: MV Keys

Marshall Spight wrote:
> dawn wrote:
> > The other difference is that you don't go more than a couple of levels
> > deep in the nesting in MV compared to the possibilities for nesting in
> > XML. Cache' (MUMPS) has more nesting. I have never encountered a need
> > for it and it seems to help with conceptual simplicity not to have more
> > nesting available within a single file.
>
> This is exactly what I'd expect.
>
> If pure 1NF were always the exactly right thing to do, we wouldn't
> have varchar. Instead we'd just use another relation, with tuples
> like (foreign key, position, character). Would anyone like that?
> No!
>
> (The canonical objection here would be performance. For the
> thought experiment, just imagine it's free.)
>
> Instead of doing this, we allow attributes of list type.
> List! Special cased for character lists only, though,
> perhaps so we can better convince ourselves that
> we didn't just throw in a non-1NF construct. :-)
>
> So let's say we relax a little and allow general list
> and relation valued attributes. Then we could
> move away from 1NF as far as we wanted.
>
> How far might we go? I expect that what we'll find
> is that the sweet spot is pretty darn close to 1NF.

As close as non-1NF is to 1NF, perhaps.

I finally scanned in and just posted a 1965 paper by Don Nelson which is the earliest paper of which I am aware related to PICK. It reads very differently than the 1970 Codd paper, as one might expect. The second paper I put out there might be a better place to start as it is an easy 4-page document.

http://www.tincat-group.com/mewsings

Enjoy! --dawn Received on Tue Feb 28 2006 - 19:58:56 CET