Apache JDO Project - Company model and inheritance strategy

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Author Company model and inheritance strategy
Michael Watzek

2005-07-08, 5:45 pm

Hi Craig,

I'm currently preparing different inheritance mappings for hierarchies
Person/Insurance of the company model. I think of providing separate
configurations for the following combinations:

1) inheritance strategy: superclass-table,
discriminator strategy: value-map

2) inheritance strategy: subclass-table,
discriminator strategy: value-map

3) inheritance strategy: new-table,
discriminator strategy: value-map

4) inheritance strategy: superclass-table,
discriminator strategy: class-name

5) inheritance strategy: subclass-table,
discriminator strategy: class-name

6) inheritance strategy: new-table,
discriminator strategy: class-name

The idea is to provide the same strategy for all classes of a hierarchy,
e.g all Person/Insurance classes have strategies
superclass-table/value-map in case of 1).

Following this idea, I'm not sure if inheritance strategy
"subclass-table" is supported with the current inheritance hierarchies
of the company model: Due to the fact that Employee has two subclasses,
both subclasses have to be mapped to the same table. Otherwise, the
mapping for Employee is not clear. The same holds true for Insurance.

Does JDO support the case of a common superclass with inheritance
strategy "subclass-table" having more than one (direct) subclasses?

Regards,
Michael
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Michael Watzek Tech@Spree Engineering GmbH
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