一对一单向添加唯一约束

Question

我将Spring Boot 2，spring-data-jpa和hibernate一起使用

我有一对一的单向关系

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public class Samplings {

    @Id
    @GenericGenerator(name = "samplings_id_seq", strategy = "com.lcm.model.SamplingSequenceGenerator")
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "samplings_id_seq")
    private Integer id;

    @OneToOne(optional = false)
    private Products product;
    ...
}   


@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
public abstract class Products extends BaseEntity {

    @Id
    @SequenceGenerator(name = "products_id_seq", sequenceName = "products_id_seq", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "products_id_seq")
    private Integer id;

    ...
}

为什么冬眠为我创建了这个约束？

alter table if exists lcm.samplings 
   add constraint UK_oofms38wiq2q4v0w40a2qdk6f unique (product_id);

我必须能够执行这种情况

用乘积y采样x 用乘积y采样z

实际上添加了休眠限制，我不能，我不明白吗？