Re: Modelling Considered Harmful

Kenneth Downs wrote:
> 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.

I sure will!

Modeling is absolutely central to what we are doing with all software development, including the full life cycle of data.

> The case can also be stated that databases are NOT models of reality.
 They
> are rather record-keeping systems.

They surely model record keeping systems from pre-computer days, right?  That does not mean they match them exactly. There is a quotation that is attributed to a George Box that goes something like this (Yes, I COULD look it up) --
"All models are flawed, but some are useful". Modeling some aspect of reality is sometimes an attempt for a precise match (which is then flawed whereever it deviates), but often it is an attempt to simplify reality into those aspects that are most relevant to and most useful in the model.

> If it can be shown that databases are
> record-keeping, that record-keeping is not modelling,

I'm not buying this line of "reasoning" at all. Using language is modeling. A form that a patient fills in at the Dr's office is a model, capturing the aspects of "reality" of use to the Dr's office.

> then it stands that
> we would not call databases models.
>
> We need to define models and records.
>
> Leaving out the silly definitions
> like a person posing for a picture some useful definitions of model
are:
>
> 1. A miniature representation of a thing
> 2. Something intended to serve, as a pattern of something to be made
> 3. Anything which serves, or may serve, as an example for imitation
> 4. Any copy, or resemblance, more or less exact.
> 5. An abstract and often simplified conceptual representation
> of the workings of a system of objects in the real world

that one comes close for me although it need not be conceptual. We can have a simulation that models something or a model airplane or a database.

> 6. a simplified description of a complex entity or process
>
> For "record", we leave out things like a 12" disc of vinyl, and we
get some
> nice stuff. I like this first one out of Webster's for the verb
record:
>
> To preserve the memory of, by committing to writing, to
> printing, to inscription, or the like; to make note of; to
> write or enter in a book or on parchment, for the purpose
> of preserving authentic evidence of; to register; to
> enroll; as, to record the proceedings of a court; to
> record historical events
>

Before preserving something as a record, you model it, often with language, but also with other communication media, such as pictures, music, video, ...

> Here is the noun version:
>
> A writing by which some act or event, or a number of acts
> or events, is recorded; a register; as, a record of the
> acts of the Hebrew kings; a record of the variations of
> temperature during a certain time; a family record.
>
> Others:
>
> 1. That which serves to perpetuate a knowledge of acts or events;
> 2. anything (such as a document or a phonograph record or a
> photograph) providing permanent evidence of or
> information about past event
>
>
>
> It should seem almost painfully obvious that the standard examples of
> employees, sales orders, inventory activity and so forth fit far more
the
> definitions for "records" than they do for "model".

Data are records, modeling some aspect(s) of reality.

> One could stretch a
> point and contend that a sales order fits the definition of model
because
> it is "Something intended to serve, as a pattern of something to be
made",
> but really it is just instructions.

instructions model with language what it really takes to do something

> Taking the other side, if you are using a database to do a huge
weather
> simulation, then we argue that the application is modelling reality,
but
> actually this is not so either. The tables cannot run the
simulation, they
> can only record the results of some other program doing so. Though
the
> records are the records of a model, they are still records, and are
not
> themselves a model.

Where did you get the idea that records are not the result of modeling or are not "models"?

> So where is the harm? Well, there is always a problem when you call
a car a
> horse, because you risk stuffing hay down the gas pipe and you can
really
> scratch the finish with those brushes. Any attempt to advance the
theory
> of databases should understand them for what they are, or the theory
will
> go off in the wrong direction.
>
> 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'm thinking you can guess the answer to that question. I believe I've already modeled my response in words. smiles. --dawn

> --
> Kenneth Downs
> Secure Data Software, Inc.
> (Ken)nneth_at_(Sec)ure(Dat)a(.com)
Received on Fri Apr 22 2005 - 17:05:43 CEST