What's right way to change an assigned identifier (with cascade) in Hibernate 3.0?

I tried using the setter and calling session.update(obj) immediately after and flushing. I got an exception like this:
org.hibernate.HibernateException: identifier of an instance of com.example.Foo altered from bar to baz

I also tried update with the old id as the explicit second argument, but that did not help.

What do you want to do ?

An id aimed to be immutable during the lifecycle of your domain object. I'am not sure this is possible, for me changing an id means create a new object and delete the old one.

I have DB rows / persistent objects that represent users and groups. The primary key is the login name or group name. There are foreign key references to these tables from elsewhere. When either the login name of a user or a group name changes, it is necessary to update the same DB row and have the change cascade to the references. Creating a new row would break the references.

Changing primary keys is a bad thing to do and should not be done often. It should be far easier to use a little bit of SQL in a separate system (i.e. psql) to make these hopefully infrequent changes.

If these changes are frequent then it may be necessary to rethink your design (if possible).

Use a surrogate key as a primary key instead of your functional key. Then you can change you login/password easily.
This is a best practice advise by hibernate team

That is the solution I had in place initially. However, my boss does not approve of surrogate keys and wants the SQL schema to be according to his taste, so I need to change the primary key.

Is it safe to do this using session.createSQLQuery()?

Apparently updates are not allowed in native SQL queries. When I try this through HQL, I hit constraints in the DB. It appears that cascade='all' is not allowed on the id element. Is there a way to specify the cascading of id changes in the Hibernate mapping or do I need to change this manually in the DB?