How to use StatelessSession with Spring Data JPA and Hibernate?

Question

I'm using Spring + Spring Data JPA with Hibernate and I need to perform some large and expensive database operations.

How I can use a StatelessSession to perform these kind of operations?

Answer 1

To get even better performance results you can enable jdbc batch statements on the SessionFactory / EntityManager by setting the hibernate.jdbc.batch_size property on the SessionFactory configuration (i.e.: LocalEntityManagerFactoryBean).

To have an optimal benefit of the jdbc batch insert / updates write as much entities of the same type as possible. Hibernate will detect when you write another entity type and flushes the batch automatically even when it has not reached the configured batch size.

Using the StatelessSession behaves basically the same as using something like Spring's JdbcTemplate. The benefit of using the StatelessSession is that the mapping and translation to SQL is handled by Hibernate. When you use my StatelessSessionFactoryBean you can even mix the Session and the StatelessSession mixed in one transaction. But be careful of modifying an Entity loaded by the Session and persisting it with the StatelessSession because it will result into locking problems.

Answer 2

A solution is to implement a Spring factory bean to create this StatelessSession and inject it in your custom repositories implementation:

public class MyRepositoryImpl implements MyRepositoryCustom {

    @Autowired
    private StatelessSession statelessSession;

    @Override
    @Transactional
    public void myBatchStatements() {
        Criteria c = statelessSession.createCriteria(User.class);

        ScrollableResults itemCursor = c.scroll();

        while (itemCursor.next()) {
            myUpdate((User) itemCursor.get(0));
        }
        itemCursor.close();

        return true;
    }

}

Check out the StatelessSessionFactoryBean and the full Gist here. Using Spring 3.2.2, Spring Data JPA 1.2.0 and Hibernate 4.1.9.

Thanks to this JIRA and the guy who attached StatelessSessionFactoryBean code. Hope this helps somebody, it worked like a charm for me.