Re: Reminder, blatant ad

Jan Hidders wrote:
> dawn wrote:
> >
> > So is data independence about data sources and having a language for
> > the interface to the dbms that can be used for multiple databases?
>
> No no no.

I didn't think so, but the VSAM to ISAM example confused me.

> Back to square one. Data independence means that the DBMS
> offers you commands to change the organization at the physical level,
> but when you issue these commands all your operations at the logical
> level, i.e., queries and updates, can remain unchanged even if they
> concern data for which the storage structure was changed.
>
> So, to test if you understood this, can you tell me when this might be a
> useful feature? :-)

Yes, master (said with sincerity). Would this be useful if you want to distribute data from a single logical entity (aka table) across multiple volumes/secondary storage devices?

If I didn't get that right, then we are at square one, but otherwise, I'm still wondering what the end-user requirements are that would prompt such changes. For example, is the reason for data independence typically performance? Thanks. --dawn Received on Wed Feb 15 2006 - 18:39:14 CST