On May 7, 2008, at 12:48 PM, Florijan Stamenkovic wrote:
Hi all,
In the "[slightly OT] data modeling question" there is some talk of
drawbacks of inheritance, specifically of vertical inheritance...
Since I am currently contemplating implementing a reasonably complex
system, and have thought of using vertical inheritance, this has got
me worried. So, what's the deal???
My situation: a structure of over 10 entities (15ish), inheritance
up to 4 levels in depth. The amount of records per entity will be
quite small (ranging from 5 - maybe 30), so I do not worry about
performance. Many operations will be defined on the topmost entity.
Relationships will almost always relate to the topmost entity, which
will be abstract. I might want to define additional subentities in
the future. Subentities will have a sufficient amount of their own
properties to discourage me from single table inheritance.
Horizontal might do, I do not think I will be changing the existing
structure once made.
I've never done inheritance till now. Am I going to commit suicide
over this?
You might want to check for suicide exclusions in your life insurance
policy. :-) David Avendasora was using Vertical with JC. He stopped.
Maybe he can provide some pointers. My advice would be to ignore that
"Subentities will have a sufficient amount of their own properties"
and use Single Table. Or, failing that, Horizontal. Vertical is the
least efficient and the least used hence has a higher probability of
bugs.
Chuck
--
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems.
http://www.global-village.net/products/practical_webobjects
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