Re: MV Keys
Date: 2 Mar 2006 06:53:32 -0800
Message-ID: <1141311212.487197.167020_at_t39g2000cwt.googlegroups.com>
David Cressey wrote:
> "Jon Heggland" <heggland_at_idi.ntnu.no> wrote in
> > Yes, he says "repeating groups" and "nonsimple domains" are "roughly
> > analogous", and uses a relational-valued attribute (RVA) as the (sole)
> > example of an attribute with a non-simple domain. But he presents
> > normalisation as something done for convenience.
>
> This is a very, very important point. If you miss the point that
> normalization was proposed as a convenience, you are going to distort the
> entire history of the adoption of the RDM both by comercial DBMS vendors and
> by database theorists. Thanks Jon.
[snip]
(And as such the RM is misnamed in my opinion. With Codd's shift from relations to relationships, it is far more a Functional Model than a Relational Model in terms of mathematics, but there you go.)
The question of MV hence distills down to the following: