Re: Reminder, blatant ad

Jan Hidders wrote:
> dawn wrote:
> >
> > I'd like to better understand data independence in terms of
> > functionality.
> >
> > Does it mean that if a new version of a DBMS tool takes the same
> > logical specification it can lay the bytes down differently on the disk
> > without application code changing?
>
> No.
>
> > Or does the decoupling of physical and logical mean that if I want to
> > store attribute data physically "along with" a different entity (table)
> > than where it is now (and rework the logical model), no application
> > software needs to change?
>
> No.
>
> It means that you can make some changes in the physical model w/o having
> to change the logical model. Note that this is different from what you
> just said because you were talking about the logical model.

I thought that was what I was saying in the first answer. How is this different?

> > I'm likely confused on this topic as I have not studied it in depth.
>
> You probably should. It is the singlemost important notion for
> understanding what the relational model is about.

It is likely because I have read a bit that I'm confused. Why would you think that a change in the physical model of a non-relational DBMS (e.g. PICK) would require reworking the logical model? --dawn Received on Fri Feb 10 2006 - 23:07:49 CET