Re: Lucid statement of the MV vs RM position?
Date: 25 Apr 2006 10:41:12 -0700
> It is conceivable to me, Jan, that in the inner sanctum the RM is
> already dead (or altered so much that 1NF, 3VL, and the IP understood
> as relations and primitive scalars are all gone), in which case I'm
> only adding my voice to what is already known by theorists. That would
> be great as it would much better align what I have seen as best
> practices with the theory.
> My goals would still include getting the word out about this fatality.
> I doubt many undergraduate courses teach that 1NF, as we knew it, is
> dead, for example. I sure don't see that knowledge having made it into
> the practitioners "common knowledge" as yet.
It shouldn't. The "theorists" you referred to, although formally not opposed to nested relations, warn for using them too enthousiastically. Never mind the sloppy data modelling attitude where one forgets to indicate that a certain list is actually a set. Finally, whether using nested relations / lists is in practice a good idea depends on how efficiently your DBMS supports them and for example can do decent query optimization on them. AFAIK the jury is still out on that one, so it is certainly not something that should be promoted in undergraduate classes as the "currently known best practices".
> [...] If you do know of an implementation of lists that
> aligns with current relational theory (which was once described as "no
> lists" or "no repeating groups"), I'm very interested.
AFAIK the thing you have in mind doesn't exist yet.
- Jan Hidders