Re: Unknown SQL

>> > The difference is that the OODBMS will not have to do the join
>> >(WHERE c.custid = p.custid) because the transactions associated with a
>> >customer are already associated with the customer, allowing direct
 access.
>>
>> Huh? Of course it has to do the join.
>
>Yes, but the relation can be handled automatically and internally without
>any necessary work for the application developer. Links between objects in
 a
>query language would also be predefined by the class model. The "WHERE
>clause" could omit many keys.

Um, you've never heard of "views", it take it?

>> A relational database management
>> system need not perform any more poorly than a
>> network model OODBMS.
>
>The implementations behind the user-interface (SQL or "pass objects") will
>get more and more similar with evolution. Relational databases will improve
>object support. Object databases will improve declarative query
>capabilities, indices and memory management.

Your reply is totally irrelevant to the points I made. If you mean that relational databases will support object references, ie pointers, you clearly do not understand what it means to be a relational database. If you think that declarative queries and indexes define the essence of relational databases, then it's no wonder that every one of my points sailed clear over your head.

Contemplate the following quotation:

"In a relational database, all information is presented to the user explicitly as values in relations."

I think it defines the essence of the relational model. It doesn't tell the whole story, but it sets the stage for all that follows.

>Today the commonly used relational databases have one big disadvantage:
>They don't support inheritance cleanly.

If you mean sub-type/super-type relationships among relations, then I have to disagree. If you mean implementation inheritance among domains, then I have to point out that this is a tremendous advantage over OO systems.

>The commonly used object databases have one big disadvantage:
>They don't live up to the quality standards that relational databases
>provide.

You forgot all the other big disadvantages -- and they are myriad. Just see everything written about databases from 1970 until about 1980 or so describing the deficiencies of network model databases and CODASYL.

Those who ignore history are doomed to relive it.

Cheers,
Bob Received on Sun Jul 22 2001 - 01:26:44 CEST