I've enabled second level cache using EHCache on Hibernate 3.1rc2. My testcase shows that if a one-on-one relationship is built using the alternate way (with a many-to-one property-ref on one side and one-to-one unique on the other), Hibernate always tries to load the referred object from the database first, and discovers that the object was already cached right after. Both test objects has cache read-write configured in the mapping files.

Anyone explains why this is happening? Is that a bug?