Re: What does this NULL mean?

"Alfredo Novoa" <alfredo_novoa_at_hotmail.com> wrote in message news:1134649609.075897.113340_at_g43g2000cwa.googlegroups.com...
>>> Database design maintenance has nothing in special.
>
>>Well then neither does the original database design.
>>One is just as critical as the other.
>
> What I mean is that they don't have significant differences. The
> catalog is a database like any other and we already have excellent
> (theoretical) tools to manage databases.

The significant difference is that one deals in static databases and the other in the dynamic change and evolution applied to databases as a result of application development.

> You are trying to mud a very simple issue for unknown purposes.

You may like to perceive database systems change management as a very simple issue, however I do not. It is the single most expensive issue in the IT management environment, once the scale of the system exceeds a certain "simplicity threashold". Expensive in terms of time and revenue.

>>In that case, out with the trivialised summary of
>>schema evolution. You have the floor. Please outline
>>what Date has said about this issue.
>
> We can manage the schema applying all the power of the RM on the
> catalog relvars.

Management of the schema, and management of the evolution of the schema are two different things.

> A very elegant and powerful way. Isn't it?

The RM is powerful but restricted.
It does not answer all questions emergent in the modern database systems environment.

-- 
Pete Brown
IT Managers & Engineers
Falls Creek
Australia
www.mountainman.com.au/software