Re: Unknown SQL

Bob Badour wrote:
> First, your earlier message talked about logical access and join criteria
> allegedly giving some advantage to OODBMSs. When I point out that RDBMSs
> have had a superior solution to the problem for quite some time now, you
> respond with physical issues (performance). Do you even understand the
> difference between logical issues and physical issues?

The two are closely joined. Every logical design decision has impact on the physical behaviour. I just posted two examples of mapping objects to tables in my other response. Their performance will differ drastically.

> I have encountered one or two specific bugs in Oracle's optimizer over the
> years, which they have probably addressed. Since I do not know the
 specifics
> of your experiments, I do not know what you did wrong to cause the
> performance problems you saw. My guess is you did not have the DBMS
> calculate the statistics properly.

Vadim has just posted the solution. The optimizer was not able to understand GROUP BY statements.

> All that said, I think all of the SQL vendors have done a very poor job at
> delivering physical independence. The OODBMS vendors have no intention of
> even trying to.

No, I think they would be very grateful for a standard, but since the language binding is tighter, the problem is more difficult. There is no "numbers-in-tables" layer to agree on. First of all you would have to differentiate between transparent persistency and declarative persistency. Then you would have to agree on a storage API, suitable for multiple languages. Then you would have to agree on a Query-API. Sun's JDO is trying to address this, but only for Java. The Query-API is a mess. That started our initiative and this thread.

> >No.
> >To circumvent the object-relational mismatch, relational databases will
> >*have to* introduce the concept of table inheritance.
>
> Huh? Why do you think that relational databases will have to lower
> themselves to the level of imperative, procedural third-generation
> programming languages to overcome mismatch? Doesn't it make much more
 sense
> to raise the level of our programming languages to match relational?

So you deny the sense of object-oriented programming? I didn't know I was discussing with a "Topmind"-sort of person. No wonder we have problems on agreeing on standpoints.

[object-relational]
> >Informix and some others are already working in this direction.
>
> I think the market has already announced to the world that Informix
 doesn't
> have a clue what their customers truly want and need.

Market and good technology have very little to do with eachother. Why does everybody buy the 11th fastest relational database, that ignores customers and ANSI standards?
...just because they are big and the decision does not cost your head...

I am not saying that the Informix approach was good. I was just trying to point out the object-relational lie of some other vendors.

> You don't get it. Object databases are a regression to technology the
 world
> discarded more than twenty years ago. Object databases will never catch up
> to the declarative abilities of relational databases precisely because
 they
> expose physical implementation details in the presentation to the user.

You don't get it.
Object databases expose less implementation details than relational databases. They don't need multiple tables for one object. They don't need to expose multiple keys for one object.

> >Times have changed.
>
> Apparently not.
>
> >Technology has advanced.
>
> Yes, it advanced to the point of SQL and then regressed back to the
 network
> model.
>
> >Today we program with object-oriented languages.
>
> How is that any different from 1969?

Times are different.
Compare the percentage of industrial use of object-oriented languages in 1969 to today.

> >Object databases are the best choice to store objects.
>
> Bullshit.

Thank you for this qualified comment.

Kind regards,
Carl

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