I have two classes, A and B. Class A is a mapped superclass that contains a particular property marked with the @Id annotation. In Class B I want to specify a different property as the primary key. From what I have seen of the JPA API the @AttributeOverride only applies to the @Column annotation. So is it possible to override primary keys in a subclass?

I have also been trying to learn about @IdClass. If I were to specify an @IdClass in my base class that utiltized the standard id and then I specify a different @IdClass in Class B will that override all keys and give me what I want?

Thanks in advance

Hi caskater4,

why would you want to override the ID? I cannot see any need for that. The subclass will inherit the ID field and its property of being the primary key. This way Hibernate can support polymorphic queries.

If you have another candidate for a primary key in your subclass then you should be able to enforce data integrity with a UNIQUE constraint on that candidate, I suppose.

CU
Froestel

Hi Froestel,

Thanks for the reply. On the one hand I completely agree that the ID should never be overridden. However I have the scenario where a property that is not the ID is the most commonly used reference to the object which unfortunately skips ehcache whenever a search is performed for that object.

To better explain my scenario imagine having an entity that stores application settings. Since it's bad practice (and unstable) to code against a database generated ID the settings are referenced by it's unique name property instead which is always gauranteed (and simpler for the programmer). Since the name property is not an ID any searches for the object goes past ehcache and right to the database causing a big performance issue. While I could make these objects their own entity class our system is designed to be generic requiring every entity class to have a common base class.

I'm pretty sure this must be a common phenomena for design and there's got to be an appropriate solution for such scenarios.