In the section 7.2 of documentation here:

http://www.hibernate.org/hib_docs/reference/en/html_single/#assoc-unidirectional

it states

"A unidirectional one-to-many association on a foreign key is a very unusual case, and is not really recommended".

I was finding that quite a surprise. It then says in section 7.3.1 here

http://www.hibernate.org/hib_docs/reference/en/html_single/#assoc-unidirectional-join

"A unidirectional many-to-one association on a join table is quite common when the association is optional".

Upon third reading I am thinking that the key point is that it is documenting the relationship between "entities" and not "components". If that that is the case then it is saying that "assocation on a foreign key is very unusual between entities is unusual" whereas it says nothing about "aggregation on a foreign key" which is where we would expect to find a cascade relationship and would not normally expect a join table.

Is my interpretation of this section of the documentation correct? If so then why? Is it because with association between entities it is normally an optional association on which case the foreign key would need to be "not null" which would effect performance?

thx