O'Reilly interview with Date

Although it doesn't cover new ground, it does provide an article of Date's comments accessible to everyone from which we could discuss various points. I can start with comments and questions about this quote from the interview, p2:

"And in this connection I'd like to say explicitly that I reject, as
proposed 'replacements' for the relational model, both (a) XML and the semistructured 'model,' which I see as reinventing the old failed hierarchic 'model,' and (b) objects and the object-oriented 'model,' which I see as reinventing the old failed network 'model.'"

My response:
1. He groups together an XML model and a semi-structured model. There is no way I would lump these two together. The mapping from the problem domain (subject area) to the model is very different between a
"structured" and "semi-structured" approach. When we are talking about
databases and dbms products, I would think that we are talking about structured data, not semi-structured. I'm aware of "XML databases" that could be used instead of a SQL-DBMS, while I'm not aware of semi-structured databases for the same purpose. Such systems would be more along the lines of a document management system, I would think.

Is there some other more common understanding of all of these terms that would prompt Date to lump an XML database into the same cateory as the Semantic Web, for example?

One possibility is that even though data would be modeled very differently and used very differently between the two, they both resolve in some fashion to tree structures. I'll grant that this might be the reason he can get away with this grouping, but is this also spin? Is it, perhaps, an effort to marry the already ensconced XML data model used at least for data exchange, to the not-exactly-stellar record of the semistructured efforts to date, hoping to disparage the xml model with this pairing?

2. The way that these alternatives are tossed aside is by marrying the models to hierarchical and network and then dismissing those as having failed already. I realze you cannot put everything in an interview, but I have read quite a bit of Date's writings and haven't seem much more rationale than what is given here.

Is there a mathematical argument that shows why these approaches should be tossed aside as having nothing to offer? Otherwise, this type of comment, similar to what is in most college database textbooks, is all I've got. The argument goes like this: We can model data based on language propositions using mathematical relations. There is no mathematically simpler way to model such data. Therefore, at the level of the logical data model, as well as the API to a dbms, there should only be mathematical relations and relational operators. This is clearly not a mathematical argument.

Is there a better argument than that or is that it? Thanks. --dawn Received on Wed Aug 03 2005 - 03:03:11 CEST