Re: Inheritance...
Re: Inheritance...
- Subject: Re: Inheritance...
- From: Kieran Kelleher <email@hidden>
- Date: Thu, 8 May 2008 10:47:01 -0400
15 entities with 30 max records per entity = max 450 records. ......
even with 100 attributes this is probably trivial data size, so I
would not go out of my way to avoid Single Table inheritance for the
sake of avoiding a lot of null fields in the database.
If it was me, for such a complex inheritance hierarchy, I would use
the Strategy Design pattern and not use inheritance at all since I
have found that complex inheritance can be a PITA to refactor as the
requirements change/grow over life of the app.... and the bonus is the
complete avoidance of EOF inheritance bugs :-)
Also, there might be opportunity to segment some lesser used property
groups into optional related objects if the domain model lends itself
to that
Anyway, just my opinion ...... there are many ways to skin the cat.
On May 7, 2008, at 3:48 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?
F
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| | >Inheritance... (From: Florijan Stamenkovic <email@hidden>) |