如何在多列上创建索引 [英] How to create indexes on multiple columns
问题描述
在用户属于特定组织的情况下，我们具有以下实体关系。我的查询看起来像是select * from User where org =：orgorselect * from User where org =：org and type =：type
We have the following entity relationships where a User belongs to a particular Organization. My queries either look like "select * from User where org=:org" or "select * from User where org=:org and type=:type"
单独的用户类索引。第一个查询将会很好，因为外键元素上的索引。第二个查询是否对org和type列指定了多列索引。如果是这样，我应该如何注释来创建一个这样的索引。
I have separate indexes on the User class. The first query will be fine, because of the Index on the foreign key element. Does the second query mandate a multi columnindex on org and type columns. If so how should I annotate to create one such index.
@Entity
class User {
...
@ManyToOne
@ForeignKey
@Index
Organization org;
@Index
Type type;
...
}
推荐答案
这是可以使用特定于Hibernate的 @Table 注释来实现的。从文件中：
This is doable using the Hibernate specific @Table annotation. From the documentation:
2.4.1实体
...
2.4.1 Entity
...
@Table（applicableTo =tableName，indexes = {@Index（name =index1，columnNames = {column1，column2}）））在表 tableName 的列上创建定义的索引。这可以应用在主表或任何辅助表上。 @Tables 注释允许您在不同的表上应用索引。预计此注释位于 @ javax.persistence.Table 或 @ javax.persistence.SecondaryTable（s）发生的位置。 / b>
@Table(appliesTo="tableName", indexes = { @Index( name="index1", columnNames={"column1", "column2"} ) } ) creates the defined indexes on the columns of table tableName. This can be applied on the primary table or any secondary table. The @Tables annotation allows your to apply indexes on different tables. This annotation is expected where @javax.persistence.Table or @javax.persistence.SecondaryTable(s) occurs.
参考
- Hibernate Annotations Reference Guide
- 2.4。 Hibernate Annotation扩展
- Hibernate Annotations Reference Guide
- 2.4. Hibernate Annotation Extensions
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