Quod est veritas

(this topic was: Re: Little design mistakes that can be easily avoided (2): Listenning to CELKO (and CELKO alikes))

"Cimode" <cimode_at_hotmail.com> wrote in message news:1180277301.744296.272570_at_h2g2000hsg.googlegroups.com...
> On 27 mai, 05:16, paul c <toledobythe..._at_oohay.ac> wrote:
> > Matthias Klaey wrote:
> > > Cimode <cim..._at_hotmail.com> wrote:
> > > ...
> >
> > > Hmm. Is this just the usual Celko-bashing in this newsgroup? Did you
> > > intend to write a parody on how to misread and misinterpert other
> > > peoples texts? You don't mean this seriously, do you?
> >
> > Usually I think much of what he writes here deserves to be bashed as it
> > is not about theory, just various flawed products, workarounds and
> > various design gospel he likes to preach. I think it's okay to talk
> > about that stuff in a product group but this is a theory group.
>
> What do you think about the design mistakes identified based on this
> thread(that was the real purpose of the thread and the reason for
> commenting CELKO's *taxonomy*)...I am talking about...
>
> --> 1 Defining keys according to human perception
> --> 2 Considering there are several realities (external/internal -
> based on human perception)
> --> 3 Believing in magic
> --> 4 Believing that a key is physical concept
> --> 5 Defining keys in function of lazy people.
> --> 6 Making sense out of CELKO writing and *taxonomies*
>

Between the realms of what is purely objective and what is purely subjective, there is a kind of "twilight zone", where truths are accepted as though they were facts, but where verification is merely a matter of establishing a consensus of perception among the relevant persons. For lack of a better term, I'll call the propositions that inhabit this twilight zone "conventional truths".

Take, for example, the following two propositions:

There are 360 degrees in a circle.
There are nine planets in the solar system.

Most of us learn that there are 360 degrees in a circle as if this were a universal truth. It isn't until some time later that we understand that it's actually a conventional truth, probably inherited from the Babylonians. I recall a feeling of deception when I found this out, sorta like the feeling Dorothy must have had upon learning that the little man behind the curtain is all there really was to the Wizard of Oz.

At that time, I might have pointed to the second proposition above as an objective fact, for purposes of comparison. Well, it turns out, the inclusion of "Pluto" as a planet was a matter of convention, rather than objectively verifiable fact. We now agree (most of us) that there are only eight planets in the solar system.

Now let's move one step closer to database data. Let's say we're designing an enrollment system for a university. One of the propositions is that students can enroll in courses. Sounds simple enough, right?

But what if a course, instead of meeting in a classroom, becomes something that is available on-line. and what if someone writes a "student-bot", a package that can "attend" an on-line course, and mimic the behavior of a student well enough to fool the relevant monitors. Who is enrolled in the course? The student-bot or the student-bot's author?

At this point, the conventions that our database is built upon become stretched, perhaps to the breaking point.

And I don't believe this example is unrealistic at all. I'd say that, in the world of information systems, we are constantly testing the limits within which conventional truth can be accepted. And when we ask whether a given database was or was not "correctly designed", we either have to confront this issue, or sidestep it by referring all such questions to some outside "competent authority".

Marshall brought up the topic of "the semantics of the data" some time ago. I believe that much of that topic is relevant to this comment of mine. I also believe that the natural keys one discovers are usually a matter of convention rather than of purely objective fact.

This doesn't have much to do with CELKO. I started a new topic for that reason. Received on Mon May 28 2007 - 15:57:33 CEST