hibernate.max_fetch_depth=8

A-->B is a many-to-one relationship.

In the <many-to-one> tag of the mapping file for A, outer-join="true" is set.

In the Java application, I used HQL "from A" to get all objects of A and for each of them traverse the association A-->B to visit B. I am expecting a SQL statement to retrieve from an outer join of A and B. But what I saw in the debug mesg are separate SQL statements: first retrieve A objects and for each of them issue another SQL statement to get the B object associated with it. There were no outer join operators.

Can't we take advantage of outer join by object traversing instead of explicitly putting outer join operators in the HQL? Or am I missing anything?

Thank you!
Stan

Try with eager fetching (chapter 7 of Hiberante In Action):

I meant left join fetch

chapter 4 of Hibernate In Action:
"Keep in mind that eager fetching strategies declared in the mapping metadata are effective only if you use retrieval by identifier, ...."

As I understand the mapped outer-join="true" will work only with Session.load(), Session.get() and queries where you specify id in the WHERE clause. That is if you need real eager fetch specify it in HQL with inner join fetch, left join fetch or set via Criteria.setFetchMode("b", FetchMode.EAGER).

--
Leonid

whats after that comma is also important ", and navigating associations" :)

Thank you for your answers! They are very helpful.
It is strange that I did not find the sentence you mentioned in the pdf version of "Hibernate in Action" ch4. Did it sometimes get revised recently?

But I did tried the session.get() and load() and they worked well. Then I tried ONLY s.get() to get an object of class A without navigating to B. It turned out that outer-join is still used. Yes, I have mapped B class as lazy="true".

I think it would be helpful to provide in the hibernate manual a conclusion of all the cases where eager fetch using outer-join is used. (if there is already such and I missed it, I apologize :)

Thanks,
Stan

"Keep in mind that eager fetching strategies declared in the mapping metadata are effective only if you use retrieval by identifier, use the criteria query API, or navigate through the object graph manually."