PIW Relationships Modelling

Marco Stahl marco.stahl at gmx.net
Sun Jul 17 10:31:00 EDT 2005


> Von: Sean Maley <semaley at yahoo.com>
> > Example:
> > 
> > entity | parent
> > ---------------
> > creature NULL
> > animal   creature
> > plant    creature
> > bean     plant
> > hemp     plant
> 
> Where searches represent the fundamental activity with
> the dataset, OLAP, we may consider keeping the schema
> denormalized; creature_type: A, M, V (animal, mineral,
> vegetable) rather than get into hierarchical data
> sets.
> 
> --------------------
> |creature_dimension|
> --------------------
> |creature_key      | : hemp, bean, etc
> |creature_type_key | : A, M, V
> |ground_depth      |
> |height            |
> |....              |
> --------------------

Thats for sure faster and easier to implement.
But I'm a friend of putting so much knowlege as possible into the modell and
the "source database".
(And i'm influenced maybe to much from objectorientated programming)

Something like 

entity     |  output
----------------------
Leguminosae  nitrogen
animal       shit

would simplefy the adding of new plants(and other entitys), creating
patterns for groups of plants(and other entitys), adding/changing 
properties/patterns for whole plant(entity)groups.

If the system is to slow in the end, we can use cached demormalized , "flat"
entity/input/output/whatever-tables for increasing search-speed.
There is no reason to go through the hierarchy every time but its good to
have the hierarchy in the background.

Saludos, Marco

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