Re: Object-relational impedence

From: Bob Badour <>
Date: Mon, 03 Mar 2008 14:45:54 -0400
Message-ID: <47cc4766$0$4037$>

David Cressey wrote:
> "Roy Hann" <specially_at_processed.almost.meat> wrote in message

>>"Thomas Gagne" <> wrote in message
>>>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.

David, the flaw in your logic is: At the level of abstraction where an RDB is two-dimensional, OO is uni-dimensional.

>>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 - 19:45:54 CET

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