Re: Relation Schemata vs. Relation Variables

From: vc <>
Date: 1 Sep 2006 09:39:26 -0700
Message-ID: <>

Jon Heggland wrote:
> There are no primary keys in Dataphor.

Right. I forgot ;)

> > but such treatment is also no
> > good since hidden row_id's is not part of the relational model.
> Agreed.
> > Is it the case that the Dataphor relational assignment does not honor
> > any constraints ?
> Of course not. It's just TCs that are an issue, and the way they do it
> does make sense.

I understand that in Dataphor it's impossible, syntactically, to refer to the old relvar value for the purpose of defining a 'real' TC constraint, right ? Interestingly, it would have been trivial to implement such feature efficiently in a multiversioning database but apparently they did not want to be implementation dependent although they could have used less efficient ways to do so in other databases..

> Jon
Received on Fri Sep 01 2006 - 18:39:26 CEST

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