Re: Hierachical structures - an overview

"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:btc8vb$721$1_at_news.netins.net...
>
> Number of tables is not a primary metric for me, however, I do think it
> counter-productive as well as counter-intuitive that if one prepares a table
> of books and another of authors, for example, and would like to associate
> the authors with the book, then in a relational model (and only in a
> relational model, it seems) one needs to have a book-author relationship
> table with two rows for a book with two authors. In most other models, one
> could have the book "file" point to the two authors with a field that is a
> list. It is often the case with such models that for efficiency, there are
> "return links" on the authors as well to point to their books, so
> referential integrity must be retained in both files. But the advantage is
> much more than having fewer tables -- it is in having tables that make sense
> to human beings in the way we use language and perceive objects.

I don't think that pointers qualify as something that falls within "the way we use language and perceive objects." Humans have to be taught about pointers and how to use them. Likewise, we have to be taught how to use the relational model. I know of no empirical evidence to suggest that one is any more complicated, or harder to learn, than the other.

Return links aren't so much "for efficiency" as they are to enable navigation in both directions. This kind of denormalized structure is suboptimal because the inherent redundancy in brings subjects the data structure to corruption, whereas the very structure of the relational equivalent is incapable of not being self-consistent.

Marshall Received on Tue Jan 06 2004 - 05:28:08 CET