指定索引（非唯一键）使用JPA [英] Specifying an Index (Non-Unique Key) Using JPA

问题描述

你如何定义一个字段，例如 email 作为使用JPA注释的索引。我们在电子邮件上需要一个非唯一的密钥，因为每天在这个字段上有几百万个查询字符，而且它没有密钥有点慢。

  @Entity 
 @Table（name =person，
 uniqueConstraints = @ UniqueConstraint（columnNames = {code， uid}））
 public class Person {
 //唯一代码和uid 
 public String code; 
 public String uid; 
 
 public String username; 
公共字符串名称; 
 public String email; 
} 
  

我已经看到了一个hibernate特定的注释，但我试图避免供应商特定的解决方案因为我们仍然在hibernate和datanucleus之间做出决定。

更新：

从JPA 2.1开始，你可以做这个。请参阅：此位置不允许使用注解@Index

解决方案

据我所知，没有跨JPA-Provider的方式来指定索引。但是，您始终可以直接在数据库中创建它们，大多数数据库将在查询计划期间自动选取它们。

How do you define a field, eg email as having an index using JPA annotations. We need a non-unique key on email because there are literally millions of queries on this field per day, and its a bit slow without the key.

@Entity
@Table(name="person", 
       uniqueConstraints=@UniqueConstraint(columnNames={"code", "uid"}))
public class Person {
    // Unique on code and uid
    public String code;
    public String uid;

    public String username;
    public String name;
    public String email;
}

I have seen a hibernate specific annotation but I am trying to avoid vendor specific solutions as we are still deciding between hibernate and datanucleus.

UPDATE:

As of JPA 2.1, you can do this. See: The annotation @Index is disallowed for this location

解决方案

As far as I know, there isn't a cross-JPA-Provider way to specify indexes. However, you can always create them by hand directly in the database, most databases will pick them up automatically during query planning.

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