Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]
Date: Thu, 16 Jun 2005 18:18:12 GMT
Message-ID: <Enjse.122609$fj1.6979675_at_phobos.telenet-ops.be>
Alexandr Savinov wrote:
> Jan Hidders schrieb:
>> >> Are you sure you are not talking about the (rather old) idea that is >> commonly known as "the universal relation assumption" or "the >> universal-relation data model"? For a few references see:
>
> I find the problems raised in UR model very similar to those motivating
> COM. However, the provided solution is hardly acceptable (it is
> typcially relational). In COM we have advantages of UR model but the
> solution is based on other principles.
Yes, you also seem to have added a little frame logic (e.g. see F-logic) and concept lattices into the mix. Both are well-known and useful theories, but hardly replacements of the relational model. For references:
http://flora.sourceforge.net/aboutFlogic.php http://www.informatik.uni-trier.de/~ley/db/conf/cla/cla2004.html
Moreover, these don't really solve the fundamental problem of the UR approach, which very much seems to be the backbone of your proposal, and therefore you have the same problems.
> select office_id
> from Offices
> where Managers.name = 'sally'
>
> is one of the things we want to automate in COM and this query has a a
> natural solution in COM.
Indeed. But this seems pretty much the only concrete improvement that you have demonstrated and it wasn't really much of a problem in the RM to begin with. Moreover, you have demonstrated in this newsgroup very convincingly that this comes at the price of a data model that is very hard to explain properly, even to experts in the field. That looks more like a step back then a step forward.
> Here are some differences between these two approaches:
> - COM is based haavily on dimension/subdimension duality for data access
> - COM uses concept graph with top and bottom concepts for representing
> syntax and semantics of data
> - COM defines its own basic interpretation of data: an item is
> group/category for its subitems; an item is a dimension value for its
> subitems; an item is a relation instance for its superitems (and some
> other basic interpetations). This changes the modelling approach itself.
> - COM defines its own general principles like what data is, how data is
> interpeted and so on, which are important not only for data modeling
> (and probably not so for data modeling) but are used for the next
> generation concept-oriented programming paradigm.
I've seen literally hundreds of articles with new proposals that made similar suggestions and claims, and which are now rightfully forgotten. Unless you show us a wide range of concrete examples where your data model really makes things simpeler, this just remains empty marketing speak.
- Jan Hidders