Java 休眠：何时使用 @Index 注释
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Hibernate: When to use @Index annotation
提问by harsh
In my scenario, I have a schema generation script to create tables and required indexes. I am wondering is there any need to define @Indexannotation in hibernate entities as well, if so why?
在我的场景中，我有一个模式生成脚本来创建表和所需的索引。我想知道是否还需要@Index在休眠实体中定义注释，如果需要，为什么？
Script:
脚本：
create table issues (id, project_id, .., status_id)
create index idx_issues_projid on issues (project_id)
Entity:
实体：
@Table(name="issues")
public class DBIssue {
..
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "PROJECT_ID")
@Index(name="INDEX_TFW_ISSUE_PROJECT_ID")
private DBProject project;
}
Hibernate configuration:
休眠配置：
<property name="hibernate.hbm2ddl.auto">off</property>
<property name="hibernate.hbm2ddl.auto">off</property>
采纳答案by chrylis -cautiouslyoptimistic-
I presume you're asking about the Hibernate @Indexannotation, which has essentially been imported into JPA 2.1. You would use @Indexanywhere you would otherwise proactively tell a relational database to index a column, primarily on a field where you know you'll be doing lots of lookups. In this case, for example, you are probably going to want to "select the DBIssues belonging to a particular DBProjectfrequently, so it would make sense to index that column in the table holding DBIssue.
我想您是在询问 Hibernate@Index注释，它基本上已导入 JPA 2.1。您可以@Index在任何您会主动告诉关系数据库索引列的地方使用，主要是在您知道将进行大量查找的字段上。例如，在这种情况下，您可能希望“经常选择DBIssue属于特定对象的s DBProject，因此在包含DBIssue.
