Re: Object-relational impedence

"Roy Hann" <specially_at_processed.almost.meat> wrote in message news:zpSdnSj5fPTYqVHanZ2dneKdnZydnZ2d_at_pipex.net...
> "Thomas Gagne" <tgagne_at_wide-open-west.com> wrote in message
> news:7vqdnf21dLOnrVHanZ2dnUVZ_tuonZ2d_at_wideopenwest.com...
> > JOG wrote:
> >> I wondered if we might be able to come up with some agreement on what
> >> object-relational impedence mismatch actually means. I always thought
> >> the mismatch was centred on the issue that a single object != single
> >> tuple, but it appears there may be more to it than that.
> >>
> > The issue as I've discovered it has to do with the fact OO systems are
> > composed of graphs of data and RDBs are two-dimensional.
>
> RDBs are not two-dimensional, they are n-dimensional. You are confusing
the
> picture of the thing with the thing. I have a three dimensional kitchen
> table. I have an RDB table with three columns (dimensions) called length,
> width and height that describes it.

Stop! You're both right!

There is a certain level of abstraction where and RDB is definitely n-dimensional. This is the level of abstraction where I spend most of my time thinking. So I tend to agree with you, Roy.

There is, however, a different level of abstraction where an RDB is two-dimensional. So Tom is not "wrong" all the way. And it may be at that level of abstraction where the OO RM impedance match comes about.

> I completely, 100% agree with that. Code is evil.
>
It appears, from reading c.o., that OO people regard data structures as evil.

It sounds like Stalinists versus Trotskyites to me! Received on Mon Mar 03 2008 - 18:36:50 CET