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As an OGM implementor, I would like to be able to map individual classes via joined inheritance. Acknowledging that most NoSQL datastores do not support joins, this is a very useful strategy for at least Datomic and presumably any EAV datastore.
Given that entities in EAV stores are represented as:
[eid] [attribute name] [value]
a natural mapping between JPA entities and EAV entities would be as follows:
@Entity
@Table(name = "persistable")
@Inheritance(strategy = InheritanceType.JOINED)
public class Persistable { @Basic Long id; @Basic String name; }
@Entity
@Table(name = "foo")
public class Foo extends Persistable { @Basic String bar; }
Would map to
persistable
persistable/id
persistable/name
foo
foo/bar
as attributes in the EAV store and eliminate unnecessary duplication of attributes.
This should be relatively easy to implement, requiring a new EntityPersister, EntityDiscriminator, and the registration of the Persister with the OgmPersisterClassResolver
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