Question

我的目的是使用executeUpdate()来执行单个DELETE，而不是循环遍历session.delete()，这非常繁琐。

我面临的问题是executeUpdate()，它不会从第一级缓存中驱逐现有的已删除实体。

这是一个非常简单的例子： -

final Session session = sessionFactory.getCurrentSession();

System.out.println("---------------------------------");
System.out.println("What's currently in 1st level cache");
System.out.println("---------------------------------");

for (Object o : session.getStatistics().getEntityKeys()) {
    EntityKey entityKey = (EntityKey) o;
    System.out.println(entityKey.getEntityName() + " -> " + entityKey.getIdentifier());
}

System.out.println("---------------------------------");
System.out.println("Ensure there are 3 project users");
System.out.println("---------------------------------");

checkArgument(session.createQuery("from ProjectUser").list().size() == 3);

System.out.println("---------------------------------");
System.out.println("Deleting all 3 project users");
System.out.println("---------------------------------");

checkArgument(session.createQuery("delete from ProjectUser").executeUpdate() == 3);

session.flush();

System.out.println("---------------------------------");
System.out.println("Latest state in 1st level cache");
System.out.println("---------------------------------");

for (Object o : session.getStatistics().getEntityKeys()) {
    EntityKey entityKey = (EntityKey) o;
    System.out.println(entityKey.getEntityName() + " -> " + entityKey.getIdentifier());
}

这是我看到的打印件： -

---------------------------------
What's currently in 1st level cache
---------------------------------
testHibernate.domain.ProjectUser -> 2
testHibernate.domain.ProjectUser -> 1
testHibernate.domain.User -> 1
testHibernate.domain.ProjectUser -> 3
testHibernate.domain.User -> 3
testHibernate.domain.Project -> 1
testHibernate.domain.User -> 2
---------------------------------
Ensure there are 3 project users
---------------------------------
Hibernate: 
    select
        projectuse0_.projectUserId as projectU1_1_,
        projectuse0_.datetime as datetime2_1_,
        projectuse0_.projectId as projectI3_1_,
        projectuse0_.userId as userId4_1_ 
    from
        projectUser projectuse0_
[TRACE] [BasicExtractor] [extract:74] - Found [1] as column [projectU1_1_]
[TRACE] [BasicExtractor] [extract:74] - Found [2] as column [projectU1_1_]
[TRACE] [BasicExtractor] [extract:74] - Found [3] as column [projectU1_1_]
---------------------------------
Deleting all 3 project users
---------------------------------
Hibernate: 
    delete 
    from
        projectUser
---------------------------------
Latest state in 1st level cache
---------------------------------
testHibernate.domain.ProjectUser -> 2
testHibernate.domain.ProjectUser -> 1
testHibernate.domain.User -> 1
testHibernate.domain.ProjectUser -> 3
testHibernate.domain.User -> 3
testHibernate.domain.Project -> 1
testHibernate.domain.User -> 2

正如您所看到的，testHibernate.domain.ProjectUser实体仍然在第一级缓存中挥之不去，即使它们已被删除。

我的问题是如何使用executeUpdate()方法从第一级缓存中清除已删除的实体？有没有官方文件解释这个问题？

谢谢。

Answer 1

这是我的解决方案，但它真的不整洁。

BaseEntity只是我们所有实体的基类。

@PersistenceContext
transient EntityManager entityManager;

@SuppressWarnings("unchecked")
public void evict(Class<? extends BaseEntity> c)
{
    HibernateEntityManager hem = entityManager.unwrap(HibernateEntityManager.class);

    Session session = hem.getSession();

    Query query = session.createQuery("select o from " + c.getSimpleName() + " o where isObsolete = false AND isDeleted = false");

    List<? extends BaseEntity> entities = (List<? extends BaseEntity>) query.list();

    for (BaseEntity e : entities)
    {
        session.evict(e);
    }
}

Hibernate：使用executeUpdate（）进行批量删除不会清除第一级缓存

1 个答案: