Criteria Add all the tables from the entity class when it only needs part of it

Question

when i create a count query with hibernate - Criteria - add all the possible table from the entity class as left join which is bad performance .

The entity :

@Entity
@Table(name = "employees")
Public Class Employees {

    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "lz_job_stat_id")
    private Integer id;

    @ManyToOne
    @JoinColumn(name = "departments_id")
    private Departments  departments;


    @ManyToOne
    @JoinColumn(name = "managers_id")
    private Managers  managers;

}

And the criteria :

public class EmployeeDao {

    public List<EmpDao> findIt(){
        .....
        Criteria crit = createEntityCriteria().setFetchMode("departments", FetchMode.SELECT);
        crit.add(Restrictions.eq("managers.deleted", false));

        crit.setProjection(Projections.count("id"));
        return crit.list();
    }
}

And the produced SQL :

select count() as y0_ 
from employees this_ 
left outer join departments department3_ 
    on this_.department_id=department3_.department_id
left outer join managers manager2_ 
    on this_.manager_id=manager2_.manager_id

now when i try the crit.list - it create a left join for all the possible tables.

when its not supposed to create a join for all of them. isnt Criteria smart enought to know i dont need this tables ? only the one i use the "WHERE CLAUSE" is there a way to explicitly tell Criteria "DO NOT JOIN THIS TABLES !!!" without SQL

Answer 1

Specify fetch type on ManyToOne annotation:

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "departments_id")
private Departments  departments;

or IMHO more preferably in criteria:

criteria.setFetchMode("departments", FetchMode.SELECT)