Re: Unknown SQL

Bob Badour wrote:
> Um, you've never heard of "views", it take it?

Yes, I have heard about views. If you read some of the other comments in this thread you will see that we have been discussing views already.

When we experimented with views on ORACLE, Sybase and MSSQL three years ago, joins between views used to be very slow. Measuring the evaluation times, we had the feeling that query optimizers could not handle joins between views intelligently. It seemed that views where evaluated and retrieved completely before constraining them by other parts of the query. I am not informed about the current state of development. I do know that MSSQL introduced indexed views some time ago. From reading newsgroups I get the idea that views still are very slow.

> >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.

No.
To circumvent the object-relational mismatch, relational databases will *have to* introduce the concept of table inheritance. Informix and some others are already working in this direction. Different approaches that call themselves "object-relational" are just using marketing hype. Serialising objects to table columns has nothing to do with object-relational: - you don't store objects but blobs
- objects are not related

Why are you talking about pointers?
We use Java.
There are no pointers.

If relational databases will not learn to disassemble objects and to put them back together again (= storing references) they will have no future.

> 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.

No.
Declarative queries currently are the strength of relational databases in comparison to object databases. Object databases will catch up and overtake.

> 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.

And?
This is where the mismatch comes from.
We are programming with objects not with values.

Normalization is unnecessary and ugly if you can store objects.

> >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.

Now this statement is totally hollow.
Please do explain how you would store:

class Person
class Employee extends Person
class Manager extends Employee

> 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.

Times have changed.
Technology has advanced.
Today we program with object-oriented languages.

Object databases are the best choice to store objects.

Kind regards,
Carl

---
Carl Rosenberger
db4o - database for objects - http://www.db4o.com