Re: Modelling Considered Harmful

"Kenneth Downs" <knode.wants.this_at_see.sigblock> wrote in message news:4v4mj2-92l.ln1_at_pluto.downsfam.net...
> I wonder if anybody would care to dispute the thesis that use of the term
> "modelling" with regard to databases does more harm than good.

[major snip]

> Nor is the meta-data a model. The meta-data for the employees table does
> not model the company, it specifies what information must be recorded to
> conform with law and policy. since meta-data is data, the meta-data is a
> record of what must be recorded. Still no model.
>
> Agree? Disagree?

I disagree. First off, my usage of the term "modelling" with regard to databases does NOT address the issue of whether or not the data in the database is a "model of reality". I don't even want to tackle that one just yet.

What I have used modelling for is to construct a "data model" prior to constructing a database. This has been enormously useful to me, and is recommended by several pioneers who know more than I do. The big value of a model is that it can illustrate some of the important features of the real thing, but it can be made in less time, and at lower cost, than the original. If the model is useful, it will make visible some of the capabilities, and some of the errors and omissions, in the real thing.

Prior to constructing a database (or other body of data), it can be very useful to construct a model, and discuss this model among the stakeholders, to discover whether a real database (or other body of data) built in conformance with the model will or will not be likely to fulfill its mission.

Data modelling isn't the only form of modelling. There's process modelling and object modelling, to name just two.
Modelling isn't the only way to anticipate the results of a contruct. There's also prototyping, to name just one.

The value of modelling goes down, as it becomes cheaper to build a database. But the model is still useful, in some ways, that the real thing is less useful for. Specifically, a model of a database is easier tounderstand than a database itself. Provided that understanding is a trustworthy guide to the actual database, there is value in that. Received on Wed Apr 27 2005 - 07:59:29 CEST