如何使用JPA/休眠创建索引，以及如何使用MappedSuperClass中的字段以及具体实体中的字段

问题描述

我有@MappedSuperClass(简化示例):

@MappedSuperclass
public abstract class MySuperClass {

    @Id
    @GeneratedValue
    private long id;

    @Column(nullable = false)
    private Date creationDate;

    // ...
}

和具体的Entity(简化示例):

and a concrete Entity (simplified example):

@Entity
public class MyEntity extends MySuperClass {
    @Index(name = "IDX_MYINDEX")
    @Column(nullable = false)
    @Enumerated(EnumType.STRING)
    private MyType type;

    @Index(name = "IDX_MYINDEX")
    @Column(nullable = false)
    @Enumerated(EnumType.STRING)
    private MyResult status;

    // ...
}

现在，我需要一个包含列MySuperClass.creationDate，MyEntity.status和MyEntity.type的索引.

Now I need an index including the columns MySuperClass.creationDate, MyEntity.status and MyEntity.type.

如果我将@Index(name = "IDX_MYINDEX")添加到MySuperClass.creationDate，则hibernate会将creationDate的索引添加到从MySuperClass继承的每个实体中.

If I add @Index(name = "IDX_MYINDEX") to MySuperClass.creationDate hibernate adds an index of creationDate to every Entity inherited from MySuperClass.

我尝试了@AttributeOverride，但是它无法建立索引.

I tried @AttributeOverride but it is not capable for indexes.

有什么想法吗? TIA！

Any ideas? TIA!

推荐答案

如果使用的是JPA 2.1，则可以使用具有其属性索引的类注释@Table

If you are using JPA 2.1 then you can use class annotation @Table with its attribute indexes

@Table(indexes = { @Index(name = "IDX_MYIDX1", columnList = "id,name,surname") })

请注意，如文档所述

如上所示，

columnlist接受列名列表作为逗号分隔的列表.

columnlist, as shown above, accepts column names list as a comma-delimited list.

如果您不使用JPA 2.1，则可以使用旧的Hibernate的@Index注释(请注意，此注释已被弃用).有一个属性columnNames，无论在哪个字段上方声明，都可以传递列名称数组.

If you don't use JPA 2.1 you can just use old Hibernates @Index annotation (note this is already deprecated). There's attribute columnNames where you can pass array of column names no matter above which field it is declared.

@Index(name = "IDX_MYIDX1", columnNames = { "id", "name", "surname"})

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