[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-4935) one to one(join column in right place) causes HQL eager fetch failure

one to one(join column in right place) causes HQL eager fetch failure --------------------------------------------------------------------- Key: HHH-4935 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4935 Project: Hibernate Core Issue Type: Bug Affects Versions: 3.3.2 Environment: linux, windows, junit test with hibernate 3.3.4, 3.4 for annotations/entityManager Reporter: Dean Hiller See the end of this post... The test case and all code can be found in here....(just modified the Cat->Kitten example till it broke).... https://forum.hibernate.org/viewtopic.php?f=1&t=1002721&p=2425506... basic summary though is if you have SELECT s FROM Cat s inner join fetch s.kitten and you redefine Cat->Kitten to be OneToOne, it works great if JoinColumn is on kitten, but if you move JoinColumn to Cat, it results in a 1+N select where the first sql got all the data needed by hibernate to fill in the Cats and their kitten. We have a 100 page result set that is doing 1+N selects here. ie. if you leave the join column on kitten, the following sql is 1+N then.... SELECT k FROM Kitten k inner join fetch k.cat; (ie. a more likely case since there may be Cats without kitten, but a kitten always have a cat...that is the situation we have in our object model). so onetoone eager fetch joins only work on half the cases out there from what I can tell and you get lucky if your join column is on the right object.