How to get an id without join in doctrine2?

I have entity like this:

/**
 *
 * @Table(name="table")
 * @Entity
 */
 class Table {

    /**
     * @Column(type="integer")
     * @Id
     * @GeneratedValue(strategy="IDENTITY")
     */
     private $id;


    /**
     * @ManyToOne(targetEntity="Entities\Users")
     * @joinColumn(name="userId", referencedColumnName="id")
     */
     private $User;


    /**
     * @Column(type="string")
     */
     private $text;


}

If i do $q->getQuery()->getSingleResult()->getUser()->getUserId()

doctrine generate query like:

SELECT * FROM table t INNER JOIN users u ON u.id = t.userId WHERE id = 100

but if i don`t need table users, how to get an userId.

In pure SQL i can just

SELECT * FROM table WHERE id = 100

and get userId without join users table.