EJB3 inheritance strange behavior

Hi all,

sorry for my not perfect English ...

I have table per subclass situation in my database. So i use
@Inheritance(strategy=InheritanceType.JOINED) to map my entities. When
i try to get the instance of subclass, everithing is OK. In my sql log
i see the query that joins two tables (mapped to superclass and mapped
to subclass that i want to get) and returns the correct result.
BUT, when i want to get the instance of superclass, i see the query
that joins table mapped to superclass and ALL tables mapped as
subclasses, though return only infomation from one header table.

Is such behavior correct? And if I have 20 subclasses (and subtables)?
can i change this behavior somehow?

i have the following structure of entities:

@Entity
@Table(name="X.Ref")
@Inheritance(strategy=InheritanceType.JOINED)
public class Ref implements Serializable{

    private Integer id;
    @Id @GeneratedValue
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }

    private String name = "";
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    private String status = "r";
    public String getStatus() {
        return status;
    }
    public void setStatus(String status) {
        this.status = status;
    }
}

@Entity
@Table(name="X.OrgAdd")
@PrimaryKeyJoinColumn(name="Pnt")
public class Organization extends Ref {
    private String address = "";
                private String full_name="";
                ...
}

@Entity
@Table(name="X.PeopleAdd")
@PrimaryKeyJoinColumn(name="Pnt")
public class Person extends Ref {
    private String sex = "";
                private String addressfact="";
                private String email="";
                ...
}

@Entity
@Table(name="X.ClientAdd")
@PrimaryKeyJoinColumn(name="Pnt")
public class Client extends Ref {
    private String client_code = "";
                private String depo_code="";
                ...
}

and several other subclasses.
I use JBOSS 4.0.5.

thanks in advance.