PostgreSQL JPA cascade partially working - database

Question

Again we probably have a very simple problem;
our database look like:
CREATE TABLE Question (
idQuestion SERIAL,
questionContent VARCHAR,
CONSTRAINT Question_idQuestion_PK PRIMARY KEY (idQuestion),
);
CREATE TABLE Answer (
idAnswer SERIAL,
answerContent VARCHAR,
idQuestion INTEGER,
CONSTRAINT Answer_idAnswer_PK PRIMARY KEY (idAnswer),
CONSTRAINT Answer_idQuestion_FK FOREIGN KEY (idQuestion) REFERENCES Question(idQuestion),
);
So a Question have many Answers.
Following in entity generated by Netbeans 7.1.2 we have field:
#OneToMany(mappedBy = "idquestion", orphanRemoval=true, cascade= CascadeType.ALL, fetch= FetchType.EAGER)
private Collection<Answer> answerCollection;
As you can see I've already added all possible orphan removal and cascade instructions for cascade removal of collection. And it's working fine but for one moment:
You can delete a Question and connected Answers only if they were created in previous 'instance' of our Application. If I first create a new Question and even one Answer and then go straight and delete it we got an error like:
root cause
Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: org.postgresql.util.PSQLException: ERROR: update or delete on table "question" violates foreign key constraint "answer_idquestion_fk" on table "answer"
Detail: Key (idquestion)=(30) is still referenced from table "answer".
Error Code: 0
Call: DELETE FROM question WHERE ((idquestion = ?) AND (version = ?))
bind => [2 parameters bound]
Query: DeleteObjectQuery(com.accenture.androidwebapp.entities.Question[ idquestion=30 ])
root cause
org.postgresql.util.PSQLException: ERROR: update or delete on table "question" violates foreign key constraint "answer_idquestion_fk" on table "answer"
Detail: Key (idquestion)=(30) is still referenced from table "answer".
If I restart (rebuild, redeploy) the application it's working though.. why? Thanks!

Answer 1

Try adding the EclipseLink #PrivateOwned extension annotation to your collection mapping.
As for the issue with deletion not working until you restart the app, two things come to mind:
You might be using very long EntityManager sessions where everything stays attached to the EnitityManager. If that's the case, it's the change of EntityManager session forced by a restart that's helping. Consider using shorter EntityManager sessions by calling EntityManager.close() when you're done with a session. Work with detached entities and EntityManager.merge() state back in when you want to modify it.
The second level cache, if any, will be cleared by a redeploy. Try disabling the second level cache and see if that helps.