title: JPA entitymanager remove operation is not performant
body: <p>When I try to do an entityManager.remove(instance) the underlying JPA provider issues a separate delete operation on each of the GroupUser entity. I feel this is not right from a performance perspective, since if a Group has 1000 users there will be 1001 calls issued to delete the entire group and itr groupuser entity.</p>
  
  <p>Would it make more sense to write a named query to remove all entries in groupuser table (e.g. delete from group_user where group_id=?), so I would have to make just 2 calls to delete the group.</p>
  
  <pre><code>@Entity
  @Table(name = "tbl_group")
  
  public class Group {
  
      @OneToMany(mappedBy = "group", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
      @Cascade(value = DELETE_ORPHAN)
      private Set&lt;GroupUser&gt; groupUsers = new HashSet&lt;GroupUser&gt;(0);
  </code></pre>