I have run into a bug in 3.6.10.Final that I can replicate and describe, but I'm not sure how to generate a useful automated test case (the application I'm working on is using Spring/JPA/Hibernate, and I don't know how to set up the test sessions and such by hand). I've traced the bug to DotNode#dereferenceEntity, and I may be able to debug it further after I garbage-collect my head. Our use case: We have a class of JPA entity that contains some basic data. A handful of these entities have some extended data, and so we have a separate class with a FK reference back to the basic class (since most of the entities don't have extended data) and a mapped Java field from the basic to the extended. The classes look like this (plus Roo ITDs): @Entity public class BasicData { @Id private long id; @Embedded private String basicInfo; @OneToOne(mappedBy="basic") private ExtendedData extended; } @Entity public class ExtendedData { @Id private long id; @Embedded private String extendedInfo @OneToOne private BasicData basic; } Standard JPA field navigation works fine; we can look up either class by PK using EntityManager#find and can navigate back and forth. The generated DDL is what we expect. However, the JPQL query "SELECT b from BasicData WHERE b.extended IS NULL" is compiled incorrectly: The correct SQL is something like "SELECT * FROM BasicData LEFT JOIN Extended ON BasicData.ID = Extended.BASIC WHERE Extended.BASIC IS NULL", but Hibernate generates "SELECT * FROM BasicData WHERE BasicData.ID IS NULL", which of course returns no records. When I turn up AST logging, I get this line: '15:32:26.242 DEBUG org.hibernate.hql.ast.tree.DotNode - dereferenceShortcut() : property extended in BasicData does not require a join.' It appears that the AST is trying to optimize away the join and is incorrectly believing that it's okay. I am happy to help create a test case and to debug the AST analyzer on my end if that will help, but I'm not sure where to start (since I'm using JPA and not direct Hibernate). -- Christopher Smith, CCNP, CCDP, MCP, LPIC-1 Sphere Systems