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Re: why hierarchy?

From: paul c <toledobythesea_at_oohay.ac>
Date: Wed, 26 Jul 2006 16:24:05 GMT
Message-ID: <FGMxg.240545$iF6.183512@pd7tw2no>


Neo wrote:

>>> example/ex007.asp
>> One hiearchy is talking about ancestors of persons, the other about origins of persons. The hierarchies record the persons twice.

>
> I can't speak for other methodologies, but dbd doesn't record things
> redundantly in the db, regardless of how many hierarchies they are in.
>
>> Relations would record them once and record ancestors once and record origins once.

>
> True, if the proper schema is used.
>
>> Many problems with hierarchies - here's one: if a user is aware of only one hierarchy and discovers that there is no such person as John and 'deletes' him, the other hierarchy is now wrong, as is the DB.

>
> I can't speak for other methodologies, but this problem does not occur
> in dbd as things are only represented once, even if they are in
> multiple hierarchies. Deleting John deletes him from both hierarchies
> in db.
>
>>> To verify which method's underlying data model is more general, one can observe the impact on existing schema/data/query when meeting future unknown data requirements (to be proposed by someone else). Would someone be willing to engage in this trivial example?
>> It does seem trivial.

>
> Could you post the script for the initial data/queries so that we can
> observe the impact on them when meeting future unknown data
> requirements (to be proposed by someone else)? The more general
> methodology will be impacted the least. Below is dbd's script. Lines
> starting with "(;" are comments.
> ...

I'm not interested in what a "main directory item" might be, nor about all the other loose lingo. Looks like all you are talking about is syntax, not any kind of precise definition of a data theory. If I were really concerned, I'd rather know what's involved to add God's father to the db.

p Received on Wed Jul 26 2006 - 11:24:05 CDT

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