I have two classes, super class and subclass. (class Foo, and class Bar extends Foo).

They use same Hibernate descriptor file:


The foo_table has a raw with the specified id, but the bar_table is empty. In this case I would like the Bar object returned to me with Foo’s properties populated, but because the inner join returns no rows, I get nothing from Hibernate.
I think the way to fix it would be to force Hibernate to use outer join. Any idea on how to do it with joined-subclass?

Doesn't seem like something you should want to do. Thinking in terms of OO, if there is a Foo record with no associated Bar record, then it's not really a Bar, it's a Foo (which is why your query returns no rows). So my guess is it's not possible, becuase it's not the right behavior.

You can get this kind of outer-join functionality using the <join> element with optional="true". See http://www.hibernate.org/hib_docs/v3/reference/en/html/mapping.html#mapping-declaration-join (I've never actually used it, just read about it).