Re: Object-relational impedence

From: Bob Badour <>
Date: Mon, 03 Mar 2008 13:41:15 -0400
Message-ID: <47cc383f$0$4041$>

JOG wrote:
> On Mar 3, 2:07 pm, Thomas Gagne <> wrote:

>>All attempts by applications to access a DB's tables and columns
>>directly violates design principles that guard against close-coupling.
>>This is a basic design tenet for OO.  Violating it when jumping from OO
>>to RDB is, I think, the source of problem that are collectively and
>>popularly referred to as the object-relational impedance mismatch.

> 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.
> I was hoping perhaps people might be able to offer perspectives on the
> issues that they have encountered. One thing I would like to avoid
> (outside of almost flames of course), is the notion that database
> technology is merely a persistence layer (do people still actually
> think that?) - I wonder if the 'mismatch' stems from such a
> perspective.

It's pretty obvious to me: object-relational mismatch is to relations as assembler-object mismatch is to objects. Received on Mon Mar 03 2008 - 18:41:15 CET

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