Fetch=join not eager fetching collections

[Baljeet Nijjhar]

Hi
I was following the examples in the 'Java Persistence and Hibernate' book with Hibernate 3.3.1 to try and load my collection upfront using fetch=join as follows:

<!-- Parent class -->
<hibernate-mapping>
    <class name="Person" table="PERSON">    
...       
       <set name="telephones" fetch="join" cascade="all-delete-orphan">
           <key column="PERSON_FK"/>
           <one-to-many class="Telephone"/>
       </set> 
...
</hibernate-mapping>

<!-- Child collection class -->
<hibernate-mapping>
    <class name="Telephone" table="TELEPHONE">    
...   
        <property name="telNumber" column="TELNUMBER"/>
    </class>
</hibernate-mapping>

I would expect that when I do a session.get(Person.class, personId), that I would automatically fetch any associated Telephones and would not have to do e.g.
Hibernate.initialise(person.getTelephones).
However, the collection is not being fetched.

I tried putting lazy="false" in with fetch="join" and all that seemed to happen was an n+1 selects generated (which I want to avoid).

Any ideas?
thanks, Baljeet.

[Benjamin Winterberg]

You could just use FETCH JOINS via HQL:

  select distinct p from Person p left join fetch p.telephones  

[Baljeet Nijjhar]

The 'problem' is that I did not eagerly fetch the parent collection also using a fetch="join"; I fetched it using Hibernate.initialize(parentCollection).
I thought this would have then loaded it, and my fetch="join" on the child collections would have kicked in, but no.
I don't quite understand why Hibernate.initialize doesn't effectively eager-fetch the parent collection.