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Re: Entity vs. Table

From: Alfredo Novoa <alfredo_at_ncs.es>
Date: Thu, 17 Jun 2004 15:39:15 GMT
Message-ID: <40d1baa0.14945460@news.wanadoo.es>


On Thu, 17 Jun 2004 09:17:50 -0400, "Alan" <alan_at_erols.com> wrote:

>> It is perfectly valid to have redundancy in the physical tables.
>
>Yes, if you denormalize to less than 3NF.

No, you don't catch this.

You can have a 5 or 6NF logical design and to have a lot of redundancy in the physical structures.

On the other hand you can have a 5 or 6NF logical design and to have a lot of redundancy in the logical tables (aggregated tables for instance).

It seems you don't understand the difference between the physical and the logical levels.

> This is done often for performance
>purposes, or ease of reporting, as well as some other reasons. But the
>argument was about 3NF and redundancy.

Normal forms have nothing to do with redundancy in the physical structures and they also allow redundancy in the logical level.

With a good DBMS you could introduce redundance for performance purposes without affecting the 5NF design.

>I guess the often ranked number 1 university in the U.S. (by U.S. News &
>World Report) in I.S. grad programs is wrong and you are right.

I don't know what university is, but it is rather probable that your guess is right.

Regards
  Alfredo Received on Thu Jun 17 2004 - 10:39:15 CDT

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