Re: Modeling question...

From: paul c <>
Date: Wed, 22 Oct 2008 19:18:41 GMT
Message-ID: <l0LLk.3253$fF3.907_at_edtnps83>

JOG wrote:
> ...
> I'm telling them, and you, that the relational model can't do it
> because it was designed to handle "formatted" propositions (sets of
> data with a high level of common predication). It is important to
> recognize that the EAV approach you are looking at just happens to use
> the RM as its physical layer, and that's it. It does not use the RM as
> a logical model, and you therefore lose all of its algebraic power.
> (Sure you keep the management system's transactional capabilities, but
> thats nothing to do with the RM).
> In fact, having abandonded it, you might as well use XML, OO or RDF
> databases and cut out the middle man. However, better imo to convince
> the client that designing a robust a priori conceptual model is worth
> doing, and that you can come and update it at appropriate intervals (I
> say this because currently the RM is the most solid framework we
> have).
> I do have sympathy, because the issue of handling semistructured and
> dynamic schema is simply an unsolved problem (as is how to handle
> missing data). Proposed "solutions" are all woeful (in fact completely
> retrograde, whisking us back to 1960's tech). As such, anything you
> try and implement for your client will inevitably be an ad-hoc hack /
> in some way or other/. We're still in the stone age of informatics i'm
> afraid. Regards, Jim.
> ...

Regarding XML and RDF, no argument, they do seem to be much more rampant techniques than the EAV phenomenon within db's per se that is usually criticised in c.d.t. Yet few in c.d.t besides you criticize their mis-application, eg., assuming all data necessarily and inherently has a tree structure or that all relations are binary (which I think you've also pointed out rather succinctly elsewhere).

Don't know why that should be other than lack of interest in c.d.t or maybe the equally rampant technical specialization in IT these days, people who deal with web "documents" seem pre-occupied with presentation, pretty much nothing else, even to the extent that I've heard them discount the RM as being insufficient to manage graphical presentation whereas I doubt if any RM expert would suggest it could - talk about cross-purposes! What little I know of CSS suggests to me that it was an earnest reaction to the unwieldiness created by the mixing-up of concepts in html and http. I can't see that motivation was anything other than a naive adhoc reaction to a small part of the problem.

Personally, I don't think missing data is the same kind of problem (other than being a label for a solution to a mis-conceived or mis-stated problem). Seems fruitless to me to try to record that which is unknown or not-understood, ie., values that cannot be agreed upon. The only approach I've seen that made sense is to recognize that by definition one can't force-fit unknown values into a relation, rather one must entertain the possibility of multiple relations.

(Pretty sure I'm not telling you anything you didn't already know but maybe others would be interested - in the thirdmanifesto discussion group there has been renewed talk of various techniques to ease the housekeeping for such additional relations under the guise of "handling missing information". With all the verbiage that's been written over the years about missing information, it's too easy to confuse that with the so-called "null column" non-solution. I I wish people would refer to that newer effort as "partial relation projection", not to say that's a good term, just one that comes to mind.) Received on Wed Oct 22 2008 - 21:18:41 CEST

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