[huygens6363]

There is a model of a thing and there is a row that stores a representation of that model of a thing.

They both are things. Ignoring the last one might be tempting, but it’s not practical.

Interestingly your own way of thought is applied, but now a level deeper again.

How do you model a row? What makes it unique? A surrogate ID is the only sensible unique identifier for such a thing as there is no “natural key” that would make sense for instances of something so general as “Row”.

What you were saying amounts to “don’t model the thing holding the model”, but experience shows the thing holding the model is itself an (often unwilling) active part of systems.

Someone here gave the example of wrongly entered PK’s by administrative personnel handing live customers. That’s IMO a good example of why you need an extra layer on top of your Actual Model(c). I can think of more.

[crabmusket]

> They both are things.

Corollary: your app is part of the real world.

[TeMPOraL]

Furthermore: bugs in your app are part of the real world, so woe to those who used keys from your app as natural/external keys in their app.