I'm trying to do an outer join on two columns that aren't Primary or foreign keys, and that are not mapped in a collection.

Something like this:

select person from Person as Person, Subscriber as subscriber
LEFT OUTER JOIN person.EmailAddress on subscriber.EmailAddress


Is this possible? If not, how can I map collections/relationships using columns that _are not_ keys??

Hibernate does not care if the association being mapped actually, physically has foreign keys in the database (highly recommended, but not necessary).

Just map away...