Re: Functional Dependencies > Uniqueness Constraints

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Thu, 31 Aug 2006 14:01:42 GMT
Message-ID: <aZBJg.6549$9u.80178@ursa-nb00s0.nbnet.nb.ca>

Jon Heggland wrote:

> Marshall wrote:
>

>>And at the physical level, it seems to me that what you
>>really want is the FDs themselves. Am I missing something?

>
> I would have thought that keys in the form of unique indexes are very
> important at the physical level. What am I missing?

While I could be wrong, I assumed he was referring to semantic optimizations like using the FD's to determine the minimal set of constraints the dbms must check for an update to guarantee all constraints. Received on Thu Aug 31 2006 - 09:01:42 CDT