Lazy children loaded when persist is called

[scatudal]

Let's say we have an entity that has a OneToMany relationship declared like this :

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "Parent")
public Set<Child> getChildren() {
 return this.children;
}

public void setChildren(Set<Child> children) {
 this.children = children;
}

When I call persist on the entity, hibernate firsts populates the list of children although I have never accessed the getter.

Here is the call in a stateless session bean:

package org.domain.services.users;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

import org.domain.SeamOne.entity.Parent;
import org.domain.services.users.ParentManager;

public @Stateless
class ParentManagerBean implements ParentManager {

 @PersistenceContext
 private EntityManager em;

 public void ChangeName(String pName, String pId) {
 Parent parent = em.find(Parent.class, pId);
 // An hibernate trace just appeared that shows a select just for
 // the parent class

 parent.setName( pName );


 em.persist(parent);
 // An hibernate trace just appeared that shows a select to populate
 // the children
 }
}

When I first saw the traces from hibernate, I didn't know for sure which call had produced the traces. I then started jboss in debug mode and stepped through the code to realize that the children were loaded on the persist call.

My code works fine, but I can't see the need for that query when the children have not been accessed because they can't be dirty.

I've tried removing the "cascade = CascadeType.ALL" and it then doesn't do the query, but I now have to call persist on the children of the class when they have been modified.

Is there a reason for that behavior?
Is that an bug?
Is there a way to circumvent this without loosing the cascading feature?


Thank you all,
Sylvain Catudal