[news.eclipse.rt.eclipselink] Re: Dynamic fetch plan with navigations

[fs5@xxxxxxx (Frank Schwarz)]

> What SQL did you get from using the hint?

Unfortunately, I cannot reproduce the observed behavior. It was like 
pre-fetching the first relationship and later fetching on-demand the 
nested relationship.

Now I am seeing an exception with the cascading query hint.
Object model: Person with self-reference "friends" as many-to-many
Query:
Query query = entityManager.createQuery("SELECT p FROM Person p");
query.setHint("eclipselink.join-fetch", "p.friends.friends");

resulting SQL: 

SELECT t2.ID, t2.FIRSTNAME, t2.LASTNAME, t0.ID, t0.FIRSTNAME, t0.LASTNAME 
FROM FRIEND t4, FRIEND t3, PERSON t2, PERSON t1, PERSON t0 WHERE 
(((t3.Person_ID = t2.ID) AND (t1.ID = t3.Friend_ID)) AND ((t4.Person_ID = 
t1.ID) AND (t0.ID = t4.Friend_ID)))

Exception:
Exception in thread "main" java.lang.NullPointerException
	at 
org.eclipse.persistence.mappings.ForeignReferenceMapping.prepareNestedJoinQueryClone(ForeignReferenceMapping.java:1491)
	at 
org.eclipse.persistence.mappings.CollectionMapping.valueFromRowInternalWithJoin(CollectionMapping.java:1560)
	at 
org.eclipse.persistence.mappings.ForeignReferenceMapping.valueFromRow(ForeignReferenceMapping.java:1338)
	at 
org.eclipse.persistence.mappings.ForeignReferenceMapping.buildCloneFromRow(ForeignReferenceMapping.java:171)
	at 
org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildAttributesIntoWorkingCopyClone(ObjectBuilder.java:1238)
	at 
org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildWorkingCopyCloneFromRow(ObjectBuilder.java:1355)
	at 
org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObjectInUnitOfWork(ObjectBuilder.java:513)
	at 
org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:461)
	at 
org.eclipse.persistence.internal.descriptors.ObjectBuilder.buildObject(ObjectBuilder.java:413)
	at 
org.eclipse.persistence.queries.ObjectLevelReadQuery.buildObject(ObjectLevelReadQuery.java:521)
	at 
org.eclipse.persistence.queries.ReadAllQuery.registerResultInUnitOfWork(ReadAllQuery.java:893)
	at 
org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:486)
	at 
org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:883)
	at 
org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:666)
	at 
org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:844)
	at 
org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:456)
	at 
org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:906)
	at 
org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2588)
	at 
org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1178)
	at 
org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1162)
	at 
org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1136)
	at 
org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1118)
	at 
org.eclipse.persistence.internal.jpa.EJBQueryImpl.executeReadQuery(EJBQueryImpl.java:399)
	at 
org.eclipse.persistence.internal.jpa.EJBQueryImpl.getResultList(EJBQueryImpl.java:517)

The exception apart, the SQL statement should use left outer joins, 
shouldn't it?

-- Frank