In my scenario, I have a schema generation script to create tables and required indexes. I am wondering is there any need to define @Index
annotation in hibernate entities as well, if so why?
Script:
create table issues (id, project_id, .., status_id)
create index idx_issues_projid on issues (project_id)
Entity:
@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:
<property name="hibernate.hbm2ddl.auto">off</property>
JPA allows us to achieve that by defining indexes from our code using @Index. This annotation is interpreted by the schema generation process, creating artifacts automatically. Note that it's not necessary to specify any index for our entities.
Indexing. The short answer is that indexing is automatic: Hibernate Search will transparently index every entity each time it's persisted, updated or removed through Hibernate ORM. Its mission is to keep the index and your database in sync, allowing you to forget about this problem.
@Column annotation is used for Adding the column the name in the table of a particular MySQL database.
The @Entity annotation specifies that the class is an entity and is mapped to a database table. The @Table annotation specifies the name of the database table to be used for mapping.
I presume you're asking about the Hibernate @Index
annotation, which has essentially been imported into JPA 2.1. You would use @Index
anywhere 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 DBIssue
s belonging to a particular DBProject
frequently, so it would make sense to index that column in the table holding DBIssue
.
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