Hibernate version:
2.1.7

Mapping documents:
In the parent class called Unit I have the following assoc defined:

<one-to-one constrained="true" outer-join="false" name="unitAccounting" class="UnitAccounting" property-ref="unit"/>

The child class UnitAccounting is defined as follows:

<class name="UnitAccounting" table="UnitAccounting" lazy="true">
...
<many-to-one name="unit" class="Unit" not-null="true" column="birthMark" index="Idx_Fk_unit"/>

Code between sessionFactory.openSession() and session.close():
Executing a simple query against the Parent (Unit) always results in two queries, one against the parent Unit table and one against the UnitAccounting table. My expectation is that with constrained = true, fetching a Unit will result in a proxy for the UnitAccounting. I'm executing the following HQL query to test (in hibern8ide):

session.createQuery("from Unit").list();

I have read the FAQ and thought I had everything correct. Am I missing something?

I've been playing around with this and can't find anything that will prevent the extra query. In fact, even when I force outer-join fetching on the one-to-one attributes, it STILL does the extra select (in addition to doing the outer join in the query for the parent!!). I'm completely lost on this one and will have to start debugging the hibernate code to figure out exactly what the heck is going on?

Anyone out there have any ideas?

This is a well-known problem with property-ref on a <one-to-one> in HB2.1. It was fixed in HB3.

Thanks Gavin.

We are planning on using hibernate3 for our production deployment late next year. I'll see if I can't get up and running with it and retest.

BTW, I hope I didn't miss this in the FAQ's, but I tried to dig around quite a bit. Seemed like using contrained="true" would fix it but no such luck. Thanks for the insight.

-Aaron