Re: The Theoretical Foundations of the Relational Model

A nice essay overall, but I have quibbles about some, and am afraid you were a bit unsympathetic to the claim that the object model has to utility and truth outside of the relational model.

On 14 Jun 2002 16:42:43 -0700, paul_geoffrey_brown_at_yahoo.com (Paul G. Brown) wrote:
> At the time (late 19th century) is was becoming clear that a lot
> of what human beings concluded about the world from observation was plumb
> wrong.

Not sure what you are referring to here. To eliminate "rationalist" talk which could not be validated, logical positivism was introduced about that time. Logic was an attempt to clean up rationalist thought, but it's a different philosophical topic than verificationism.

> What the logical philosophers did was to try to see if this
> dissonance was the consequence of poor habits of thought. The whole
> exercise culminated in an attempt to place all of mathematics upon a
> foundation of logic (until one M. Goedel put the kybosh on that! But I
> digress. . .)

Godel and has pals including Turing. But really, the attempt to come up with a perfect rational language goes back at least to Leibniz and Descartes, well before Boole.

> When we point to a group of propositions with an identical structure
> (refering to the same kinds of things in the same relationship to one
> another) we label that group a 'relation'. It doesn't really matter what
> order they appear in, or what order the elements appear in.

An oversimplification popular amongst relational theorists. Doesn't matter to whom?

> Why? Because we can reason about the propositions contained
> within relations in an orderly, deterministic fashion.

Not unless you order them first.

> The whole sum of Ted Codd's great insight is that all of
> the programming language stuff about 'references' and 'identity' and
> 'order' can (and should) be eliminated without losing any representational
> power.

And that's the big, black hole in relational theory: identity. OOP posits identity as important. The issue is far from settled philosophically. The attempt to eliminate it is a remnant of the projects of perfect rationalism that you seem to feel Godel proved impossible. OOP reintroducing identity in a useful fashion is a very interesting topic you can't just wave off this way.

> The principles and practices that find expression in 'the relational
> model' are not really about programming at all. They are an attempt to
> describe a model of rational thought that can be written into a computer
> program (a DBMS).

"Attempt" is the important word here.

> Relational theory people are only really interested in computers to the
> extent that they can use them as tools to automate their model (and it needs
> to be pointed out that the only kinds of models you can automate are those
> with a firm theoretical foundation.)

Plenty of bad models are automated all over town.

And it's not clear that relational theory people are interested in anything but relational theory, that's just human nature.

You make a good case, but overstate it in several areas.

Joshua Stern Received on Sat Jun 22 2002 - 21:23:00 CEST