JPA/Hibernate - identifier of an instance of x was altered exception

Question

I have a JPA/Hibernate object which uses a composite key as the primary key. I am trying to read the object from the database and make an update.

Lets say the primary key is (id and name) and the following rows exist in the database.

1   john   London
2   bob    Birmingham
3   Dave   Kent

If i load an object using the key (1,john) then everything works fine. If i load it using the same primary but with a difference case using (1, John) then i get the following exception:

org.hibernate.HibernateException: identifier of an instance of Document was altered from com.myPck.test1.documentsPK[ Id=1, msgOwner=john ] to com.myPck.test1.documentsPK[ Id=1, msgOwner=John ]; 

After i load the row i do update it using JPQL but i dont update any of the primary key columns. Interestingly if i search for a row that does not exist i dont get that exception. It only occurs if i search for a row that does exist but the case used on the key is different from what is actually in the database.

What could be causing this and how do i resolve it?

Thanks

Answer 1

Can you post the code for the Compound Key class that you are using. My guess is that you have a badly implemented equals and hashCode method on the compound primary key class.