[hibernate-issues] [Hibernate-JIRA] Created: (HHH-7287) Problem in caching proper natural-id-values when obtaining result by naturalIdQuery

[Guenther Demetz (JIRA)]

Problem in caching proper natural-id-values when obtaining result by naturalIdQuery
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                 Key: HHH-7287
                 URL: https://hibernate.onjira.com/browse/HHH-7287
             Project: Hibernate ORM
          Issue Type: Bug
          Components: core
    Affects Versions: 4.1.2
         Environment: Database access with isolation level < SNAPSHOT
            Reporter: Guenther Demetz


Problem was originally exposed by Madhumita Sadhukhan in a email to hibernate-dev at lists.jboss.org at Fri 4/27/2012 .
The bug (email point 6) get isolated by following matrix-test-case:

{code:title=org.hibernate.test.naturalid.mutable.MutableNaturalIdTest.java|borderStyle=solid}
        @Test
	public void testModificationInOtherSession() {
		Session s = openSession();
		Transaction t = s.beginTransaction();
		User u = new User( "gavin", "hb", "secret" );
		s.persist( u );
		t.commit();
		s.close();

		s = openSession();
		
		// Use transactionless session
		assertNotNull( s.byNaturalId( User.class ).using( "name", "gavin" ).using( "org", "hb" ).load());

		// CHANGE natural-id values in another session
		Session other = openSession();
		other.beginTransaction();
		u = (User) other.byId( User.class ).getReference( u.getId() );
		u.setOrg( "zz" );
		other.getTransaction().commit();
		other.close();
		// CHANGE APPLIED
		
		u = (User) s.byId( User.class ).getReference( u.getId() );
		assertEquals(u, s.byNaturalId( User.class ).using( "name", "gavin" ).using( "org", "hb" ).load()); // found with cached old-values, OK
		
		
		User u2 = (User) s.byNaturalId( User.class ).using( "name", "gavin" ).using( "org", "zz" ).load();  // the internal query will 'see' the new values, because isolation level < SERIALIZABLE
		assertEquals(u, u2); // is it right here having u2 != null ? Yes, if we continue to see NaturalIdLoadAccess as a plain query. Maybe something to discuss
		assertEquals("hb", u2.getOrg()); // entity itself must still contain the old value
		assertNotNull( s.byNaturalId( User.class ).using( "name", "gavin" ).using( "org", "hb" ).load()); // this fails, that's the bug
		s.close();

		s = openSession();
		s.beginTransaction();
		s.delete( u );
		s.getTransaction().commit();
		s.close();
	}
{code}

CAUSE:
The problem raises, when natural-id get resolved by query.
Here Hiberante uses the search-natural-id values for updating the cache, probably not being aware that in such situation they could differ from the natural-id-values in the current entity state. The cache-update then detects the old-values as obsolete and removes them, this explains why the second lookup with old values suddently returns null.

SOLUTION PROPOSAL:
After natural-id get resolved from query, first load the entity by identifier, and then cache the natural-id-values taking them from the entity state.



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