JPA 2.1带有函数的列的索引注释 [英] JPA 2.1 Index annotation for columns with a function

问题描述

在我的Hibernate项目中，我添加了如下索引：

  @Entity 
 @Table（name = MY_TABLE，索引= {
 @Index（name =idx_user_name，columnList =name），
 @Index（name =idx_user_email，columnList =email）
} ）
  

这很好，但是当我想像这样创建一个索引时会发生什么： p>

  CREATE INDEX ON my_table（lower（name））; 
  

如果我使用以下注释，将得到 AnnotationException
pre $ lt; code> @Index（name =idx_lower_name，columnList =lower（name））


我希望通过Hibernate + JPA 2.1创建索引来发布我的项目。是否可以通过索引注释来应用函数？

或者，我应该在部署中运行一个SQL脚本，以通过SQL自己添加这些索引？

我可能只是格式化 columnList 错误，或者可能有一个字段未在文档中描述I' m缺少。

解决方案

在JPA 2.1中不能使用基于函数的索引。

JPA提供了从特定数据库中抽象的方法。每个数据库都有自己的FBI实现，可以差别很大。
因此，它不是标准的一部分。

我窥视了Hibernate代码，看看FBI是否有未公开的功能。不幸的是，只有基于列的索引是支持。

您应该在部署时运行SQL脚本来创建索引。 p>

In my Hibernate project, I add indices like so:

@Entity
@Table(name="MY_TABLE", indexes = {
    @Index(name = "idx_user_name", columnList = "name"),
    @Index(name = "idx_user_email", columnList = "email")
})

Which works just fine, but what happens when I want to make an index like this:

CREATE INDEX ON my_table (lower(name)); 

If I use the following annotation I get an AnnotationException:

@Index(name = "idx_lower_name", columnList = "lower(name)")

I wish to ship my project with the indices made via Hibernate + JPA 2.1. Is it possible to apply functions via the Index annotation?

Or should I just run an SQL script on deployment to add these indices myself via SQL?

I could just be formatting the columnList wrong, or there could be a field not described in the documentation I'm missing.

解决方案

It is not possible to use a function based index in JPA 2.1.

JPA provides means to abstract from a specific database. Every database has its own implementation of FBI which can vary greatly. Hence, it is not part of the standard.

I peeked into the Hibernate code to see whether there might be an undocumented feature for a FBI. Unfortunately, only column based indexes are supported.

You should run a SQL script on deployment to create your index.

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