OneToMany 不会在 H2 数据库上使用 ON DELETE CASCADE 创建外键

Question

我正在使用 Spring Boot 1.3.1.RELEASE 与 Hibernate 和 H2 进行集成测试。以下是我的具有单向 OneToMany 关系的实体。由于某种原因，生成的外键 DDL 不包含 ON DELETE CASCADE。根据 H2 documentation 支持参考操作。我也尝试过双向 OneToMany，但仍然缺少 ON DELETE CASCADE。请指教。如果可能的话，我想避免使用 Hibernate 特定的东西。提前谢谢你。

我的实体：

@MappedSuperclass
public abstract class DomainObjectLong implements Persistable<Long> {
    @Id
    @GenericGenerator(name="ID_GEN" , strategy="increment")
    @GeneratedValue(generator = "ID_GEN")
    private Long id;

    @Override
    @Transient
    public boolean isNew() {
        return id == null;
    }
}


@Entity
@Table(name = "event")
public class EventVO extends DomainObjectLong {
    @Column(name = "time", nullable = false, updatable = false)
    private LocalDateTime time = LocalDateTime.now();

    @Column(name = "type", nullable = false, updatable = false)
    @Enumerated(STRING)
    private EventType type;

    @OneToMany(cascade = ALL, fetch = EAGER, orphanRemoval = true)
    @JoinColumn(name = "event_id", nullable = false)
    private List<EventDataVO> data;
}


@Entity
@Table(name = "event_data", uniqueConstraints = {
        @UniqueConstraint(columnNames = {"event_id", "key"})
})
public class EventDataVO extends DomainObjectLong {
    @Column(name = "key", length = 128, nullable = false, updatable = false)
    private String key;

    @Column(name = "value", length = 512, nullable = false, updatable = false)
    private String value;
}

属性：

datasource.runtime.url=jdbc:h2:mem:runtimetestdb;DB_CLOSE_ON_EXIT=FALSE
datasource.runtime.driver-class-name=org.h2.Driver
hibernate.dialect=org.hibernate.dialect.H2Dialect
hibernate.show_sql=true
hibernate.format_sql=true
hibernate.hbm2ddl.auto=create-drop

日志：

23:40:44.648 [localhost-startStop-1] DEBUG org.hibernate.SQL - 
    alter table event_data 
        add constraint FK_6xxhltyiilvlk02730x7mu7cu 
        foreign key (event_id) 
        references event
Hibernate: 
    alter table event_data 
        add constraint FK_6xxhltyiilvlk02730x7mu7cu 
        foreign key (event_id) 
        references event

Answer 1

JPA 不生成 ON DELETE CASCADE 约束。

原因是级联是在JPA级别上用toMany或toOne映射映射中的cascade属性完成的。

如果数据库将级联删除，则状态将与持久性上下文不匹配，JPA 将生成删除，但数据库记录已被删除。

OneToMany 不会在 H2 数据库上使用 ON DELETE CASCADE 创建外键

OneToMany doesn't create foreign key with ON DELETE CASCADE on H2 database

hibernate

h2

spring-data-jpa

jpa-2.1