How to mix inheritance strategies with JPA annotations and Hibernate?

Question

According to the Hibernate Reference Documentation it should be possible to mix different inheritance mapping strategies when using Hibernate\'s XML-Metadata:
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Answer 1

According to the Hibernate Reference Documentation it should be possible to mix different inheritance mapping strategies when using Hibernate's XML-Metadata (...)

Actually, it's not really supported, they are "cheating" using a secondary table to switch from the single table strategy in the example of the documentation. Quoting Java Persistence with Hibernate:

You can map whole inheritance hierarchies by nesting , , and mapping elements. You can’t mix them — for example, to switch from a table-per-class hierarchy with a discriminator to a normalized table-per-subclass strategy. Once you’ve made a decision for an inheritance strategy, you have to stick to it.

This isn’t completely true, however. With some Hibernate tricks, you can switch the mapping strategy for a particular subclass. For example, you can map a class hierarchy to a single table, but for a particular subclass, switch to a separate table with a foreign key mapping strategy, just as with table per subclass. This is possible with the mapping element:

  

    ...

    
    ...
    
      
        

        
        
        
        ...
      
    

    
      
      ...
    
  ...
  

And you could achieve the same with annotations:

Java Persistence also supports this mixed inheritance mapping strategy with annotations. Map the superclass BillingDetails with InheritanceType.SINGLE_TABLE, as you did before. Now map the subclass you want to break out of the single table to a secondary table.

@Entity
@DiscriminatorValue("CC")
@SecondaryTable(
    name = "CREDIT_CARD",
    pkJoinColumns = @PrimaryKeyJoinColumn(name = "CREDIT_CARD_ID")
)
public class CreditCard extends BillingDetails {
    @Column(table = "CREDIT_CARD",
        name = "CC_NUMBER",
        nullable = false)
    private String number;
    ...
}

I didn't test this but you could maybe try to:

• map A using a SINGLE_TABLE strategy
• map BB, CC, etc using the @SecondaryTable annotation.

I've not tested this, I don't know if it will work well for BB1, BB2.

Reference

• Java Persistence with Hibernate
  • 5.1.5 Mixing inheritance strategies (p207-p210)