why same Id on @MappedSuperclass when @Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)

user_3105961 0
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I try to have 2 tables, as follows:

MISExercise (table)

ID NAME ...

2 a

MISInteractiveExercise(table)

ID NAME ...

1 b

They must have no same id. And they are inherited from the same base. My code is :

@MappedSuperclass  
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public abstract class MISExerciseBase {
    @Id
    @GeneratedValue(strategy = GenerationType.TABLE)
    private Integer id; 

    ...
}

@Entity
public class MISExercise extends MISExerciseBase{
   ...
}

@Entity
public class MISInteractiveExercise extends MISExerciseBase{
   ...
}

Unfortunately, I find that the table of MISExercise and the table of MISInteractiveExercise can have the same id. When I google it I find http://openjpa.208410.n2.nabble.com/same-Id-on-mapped-superclass-td2435374.html. @Kaayan seems has the same problem. But I can't get help from that page.

And it seems if I use @Entity not @MappedSuperclass, it will be fine. But why, and what's the good way?

mappedsuperclass inheritance hibernate
2 Answers

I ran into a similar issue. This fixed it for me by adding this as a class level annotation:

@SequenceGenerator(initialValue = 1, name = "idgen", sequenceName = "parentseq", allocationSize = 1)

You don't need to specify ALL that stuff, but the important part is the sequenceName and making sure that the child classes are using the same one as the parent class.

user_32882580
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