Problems in many-to-many relations when updating parent object in hibernate?

Question

I have many-to-many relationship between user and topic tables. Join table is user_topic. Topic entity has this:

@ManyToMany(fetch = FetchType.LAZY, targetEntity = IntermediateUser.class)
    @JoinTable(name = "user_topic", catalog = DataBaseConstants.DBCATALOG, joinColumns = { @JoinColumn(name = "topic_id", nullable = false, updatable = false) }, inverseJoinColumns = { @JoinColumn(name = "user_id", nullable = false, updatable = false) })
    @Cascade(value = CascadeType.DELETE)
    public Set<IntermediateUser> getVotingUsers() {
        return votingUsers;
    }

I update collection 'votingUsers' in transient topic instance and then call hibernate session's update method. I don't use method setVotingUsers but instead I clear votingUsers collection by method votingUsers.clear() and then add by votingUsers.add(voter); To update I call this method:

sessionFactory.currentSession().update(topic);

As a result I see in my log the following lines

DEBUG org.hibernate.SQL- update javahelpdb.topic set content=?, `PUBLISH_DATE`=?, rate=?, forum=?, title=?, user=?, viewquantity=? where topic_id=?
DEBUG org.hibernate.SQL- delete from javahelpdb.user_topic where topic_id=?
DEBUG org.hibernate.SQL- insert into javahelpdb.user_topic (topic_id, user_id) values (?, ?)

All parameters are correct. I expect to have only one query like:

update user_topic set topic_id=?, user_id=? where topic_id=?

How to instruct hibernate do update user_topic instead of delete and insert?

Thank you!

Answer 1

I think this is the normal Way how hibernate behaves. So you can't really do anything about it and if the relationships and the parameters are correct why bother?