Further reading for Recursive Hierarchy Data Modelling

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Further reading for Recursive Hierarchy Data Modelling

Post  John Staples on Sat May 23, 2009 2:27 pm

Hi all

I need to research Recursive Hierarchy Data Modelling in depth.

I have read: www.dbmsmag.com/9809d05.html

Can any readers of this forum point me in the direction of any other _detailed_ material on this subject?

With anticipatory thanks

John Staples. UK.

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Re: Further reading for Recursive Hierarchy Data Modelling

Post  ngalemmo on Tue May 26, 2009 11:59 am

He discusses it in his book, but the article pretty much covers the topic. Personally, I prefer to use a parent level attribute instead of the 'top flag'... it gives a little more information as to where you are in the hierarchy.

Do you have specific questions on the approach?
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Re: Further reading for Recursive Hierarchy Data Modelling

Post  John Staples on Tue May 26, 2009 2:39 pm

Yes, I have read the book article, chapter 6, entitled "Variable-Depth Hierarchies".
However, detail from another author can often result in a broader understanding of a subject.

I agree with your 'Parent level attribute'.

My only question is; can changing / adding additional levels at a future date give rise to problems?
My thinking is 'No', in so far as the 'Level Name' and the 'Subsidiary Key' are tied together. The level is probably immaterial?

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Re: Further reading for Recursive Hierarchy Data Modelling

Post  ngalemmo on Tue May 26, 2009 4:23 pm

"can changing / adding additional levels at a future date give rise to problems?"

I would say... it depends. In the general sense, no, not if the level has no particular business meaning... such as an employee hierarchy, where the title or position in the company is an attribute of the employee, not the hierarchy itself.

But there are cases where hierarchy levels are themselves labled and have meaning, but these are usually represented with flattened structures and not recursive structures (for which you would use a bridge). But if such a recursive hierarchy existed, the challenge isn't so much keeping the heirarchy intact, but rather keeping track of what meaning a particular level had to the business.
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Re: Further reading for Recursive Hierarchy Data Modelling

Post  John Staples on Tue May 26, 2009 5:08 pm

ngalemmo

Thank you for your advice & comments ... it is appreciated.

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