Re: domain questionnaire

> I've never been able to make any use of the distinction between
> logical and physical data models -- so I guess I tend to disregard
> what others may value highly.

I may be misconstruing the difference between logical and physical models, but I've always treated them like the difference between interface and implementation of objects. That is, those issues that are purely physical take place out of the view of the clients of the database.

This has to do with ripple effect.

Alter a column and you might have to alter the processes that work on that column. Alter a table, and you might have to alter many processes that work on that table. But alter a tablespace (Oracle), and only the DBA has to know about it. The change won't ripple up.

Tablespaces are an example of a physical construct.

BTW, the difference between the ER model and the Relational model is, as I understand it, the difference between the conceptual model and the logical model.
That's not the same as the distinction between the logical and physical models.
Which is the distinction you've never found a use for?

--
Regards,
    David Cressey