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

[Dean Hiller (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-4935?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=35637#action_35637 ] 

Dean Hiller commented on HHH-4935:
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YES YES YES, I just found a workaround(thank god).  Use ManyToOne and OneToMany and it now goes back to a single select!!!!

yeahhhhhhhh

> 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#p2425506
> 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.

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