Re: relational vs object

In article <a6q04q$psu$04$1_at_news.t-online.com>, carl_at_db4o.com says...
> "Neil Burnett" <neil_at_efc.be> wrote:
> > So, OODBMS are great for the programmer.
>
> It would be very nice if more programmers would realize this.
>
>
> > I didn't read anything in
> > there about data integrity or ad hoc querying
>
> I was writing about the "cons" of object databases.
> Relational databases clearly are stronger in supporting
> integrity constraints and querying.

As for querying, there is of course OQL, although very few products support it for the time being.

The ODMG standard does not define key constraints for any of its three language bindings. Key constraints are at the core of the relational model, any you won't find a RDMS without key support. Keys can be simulated in most (all?) ODMSs by using unique indices, albeit not in a standard way.

Foreign keys and relationships serve the same purpose, altough relationships are not enforced automatically. The fact that relationships in ODMG are stored with inverses simplifies the implementation of more advanced constraints (especially when it is neccesary to follow a "many"-path to implement the constraint) significantly compared to RDMS where explicit joins are required.

I can't think of any constraint type that is easier to handle in an RDMS compared to an ODMS except key constraits.

>
>
> > - the two most important things for the end user.
>
> I agree.
>
> There are some object databases that do featutre integrity constraints.
> Some also support OQL or SQL also, although the supported subsets are
> not too extensive.
>
>
> Kind regards,
> Carl
> ---
> Carl Rosenberger
> db4o - database for objects - http://www.db4o.com
>
>
>
>

-- 
 Per Johan Persson - per_at_juggler.net
 Problematisk Institutt
 University of Oslo, Norway
 http://www.stud.ifi.uio.no/~perjp
 
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