Re: The Practical Benefits of the Relational Model

"David Cressey" <david_at_dcressey.com> wrote in message news:WOfr9.190$0I3.16276_at_petpeeve.ziplink.net...
> In this context, who is a database "user"?

Good question David as it is the key to my argument here. A user is anybody (or anything) that has (been given) the right to access (at least some of) the data in the database, with whatever interface they desire (as long as ultimately the interface is just relational expressions).

Now these users *cannot be trusted*. We must allow them to be stupid and/or malicious and still maintain a working and integral database.

If users need to wait for other stupid/malicious uses to complete in-flight transactions, then the database will not be useable. E.g.

BEGIN TRANSACTION
UPDATE table SET col = X
<go on holiday for two weeks>
IF RAND() > .5 COMMIT
ELSE ROLLBACK Traditionialy such problems are fixed by mandating database access only via trusted 'applications', but going forward we should be looking at complete application independence for the RDBMS, which means that you cannot *trust* the applications accessing your database.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Thu Oct 17 2002 - 12:55:57 CEST