Question

Noticed that if I want to read some data and if I do not have a transaction context I will not be able to do so because

org.hibernate.HibernateException: No Session found for current thread

For reading data , is not required a transaction normally.

So in order for Spring to manage the session it needs to have a transaction even for read only operations like selects… ?

Is that not an overhead ?

PS.I do not want to open and close session manually…

Thanks a lot.

Answer 1

@Transactional tells spring to open and close a session, in addition to instructing it to start and commit a transaction. This is not very straightforward, but that’s how it works. So if you don’t have @Transactional, no session gets opened. Here are your options:

• use @Transactional(readOnly=true) – the purpose is to have a read-only transaction. I recommend that one
• use JPA EntityManager injected with @PersistenceContext. It will open a new underlying session for each invocation. Not that good option. But you should consider using EntityManager with a readOnly=true transaction
• Use an additional aspect/interceptor/filter to open and close session. That would be hard, and you may end up confused by the spring implementation of hibernate’s current session concept.