Re: XQuery (and XML) vs LISP
Date: Sun, 12 Feb 2006 13:45:01 GMT
Mark Johnson wrote:
> Christopher Browne <cbbrowne_at_acm.org> wrote:
>>The trouble is that relations require taking something of a "set" >>perspective, and if facts aren't being expressed that way naturally, >>well, down that road lies some ghastlyness :-).
> The thing that has bothered me is that those promoting the relational
> model typically provide worthless examples, typically employee and
> department, and seem to almost religiously avoid non-trivial working
> examples, particularly those that might seem problematic for the
Its the same reason that babies get fed milk first, mashed food later and finally solids! You start simple to maximise the likelihood that the reader will "get it" and hopefully be able to employ the techniques to the complex problems they face. Pretty simple IMO.
> For example, what is a type? What goes in the 'set', as you express
> it, never mind any particular domain? Why is a book a 'type', when
> there are various sorts of books? Why is a chapter a 'type', when the
> chapters in the same book might be of a very different sort? Is the
> appendix which is more an index a type to itself? And so on. Are the
> paragraphs a 'type', and is the paragraph in chapter 4 different than
> the paragraph entities in relation chapter 5? To normalize things does
> it require literally hundreds and hundreds of 'relations'/tables to
> represent the structure?
Have you seen "hundreds and hundreds" first hand? What were they responsible for expressing?
> Just think of the 'joins'. And wasn't the RM
> intended to free people from the 'tyranny of structure'?
Nope - where you get an idea like that? The aim is to "improve" the structure and still make sure that physical aspects don't (irrationally) impinge on the logical interests.
Cheers, Frank. Received on Sun Feb 12 2006 - 14:45:01 CET