Changes between Version 6 and Version 7 of ebXMLPersistenceLayer
- Timestamp:
- 08/03/08 10:58:01 (17 years ago)
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ebXMLPersistenceLayer
v6 v7 33 33 The fourth strategy is to represent inheritance relationships as relational foreign key associations. Every class/subclass that declares persistent properties—including abstract classes and even interfaces—has its own table. The primary advantage of this strategy is that the SQL schema is normalized. A polymorphic association to a particular subclass may be represented as a foreign key referencing the table of that particular subclass. This seems a preferred strategy but its performance may be detrimental for large class hierarchies as queries require a join across many tables. 34 34 35 TODO conclusion? 35 36 At this point the second strategy, "Table per concrete class with unions", has been chosen to map the OO inheritance relations in the [wiki:ebXMLObjectModel ebXML Object Model] to the relational database realm. 36 37 37 38 ----
