#ManyToOne with native query leads to N+1 select - mysql

Question

I know the problem with N+1 select is well-known, but trying using different fetching strategies does not help to avoid it when I use native query.
I have 2 entities: A and B that correspond to the mysql tables A and B.
Several rows in table A could have the same b_id, that's why I use #ManyToOne annotation.
#Entity
#Table(name = "A")
public class A {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String name;
#ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
#Fetch(FetchMode.JOIN)
private B b;
}
I also create entity B.
#Entity
#Table(name = "B")
public class B {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String url;
}
I need to find all rows in A that are linked only for 1 row in table B. So I create native query in my ARepository
public interface ARepository extends JpaRepository<A, Integer> {
#Query(value = "SELECT a.id, a.b_id, a.name, b.url "
+ "FROM a "
+ "JOIN b ON a.b_id = b.id "
+ "GROUP BY a.b_id "
+ "HAVING count(a.b_id) = 1, nativeQuery = true)
List<A> getLinkedOnce();
But when when I run my restcontroller that just call getLinkedOnce method from repository, I see that in console, 1-st my query is called, then there are number of selects for each row in A that are end with
from B b0_ where b0_.id=?
I try to use different approaches, LAZY, EAGER and it does not work. I think because there is a usage of native query. But maybe the reason is another.