Dear Hibernate users,

I have a conceptual question regarding the eager fetch. In the tutorial example, I noticed that within a session transaction, I can write either

Person aPerson = (Person) session.load(Person.class, personId)

or

Person aPerson = (Person) session
.createQuery("select p from Person p left join fetch p.events where
p.id = :pid")
.setParameter("pid", personId)
.uniqueResult();

The later one is mentioned as eager fetch. I wonder what is the difference between the two approaches of fetching the person object, given its id?

Any clarification or explanation is deeply appreciated.
Jackie

Hi,

1. Person aPerson = (Person) session.load(Person.class, personId)
Will only return back an uninitialized proxy. There will be not database hit. The select statement will be only issued when you call a getter on the aPerson.

2. Person aPerson = (Person) session.get(Person.class, personId)
Will issue a select statement directly.

3. Person aPerson = (Person) session.createQuery("select p from Person p left join fetch p.events where p.id = :pid").setParameter("pid", personId) .uniqueResult();

Will issue a select statement to load the Person and the Set of event. The keyword 'fetch' mention that the associated are really loaded and are not proxied (if you have specified lazy="true" in hbm).

Rgds