Differences in Transactionmanagement Hibernate and JPA Transactionmanager

[TheFriedC]

hi!

i got a simple test-application for finding out some differences in transaction-behavior between using native hibernate and the hibernate implementation of JPA because i want to switch an application from pure hibernate
to JPA 2.0

i made this tes app because, when using hibernate (sessionfactory/hibernatetransactionmanager) it is not necessary to put a @Transactional annotation to a method to persist an entity. in jpa (from hibernate) nothing will be persisted without the @Transactional
there is one config using hibernate SessionFactory and spring's HibernateTransactionManager both using the same datasource bean

the other config uses a LocalContainerEntityManagerFactoryBean and JPATransactionManager.

i also use the hibernate/jpa templates provided by spring for data access. these are used by a repository class and the repository class is accessed by a facade.

in the facade, i put a @Transactional annotation on the required methods. therefore i discovered confusing behavior.

here the methods i use in the tests:

method for testing the behavior:

public void writeNewTestEntityToDB()
	{
		TestEntity te = new TestEntity();
		te.setName("hi!");
		te.setHistory(new EntityHistory(new Date(), 1L));
		
		getFacade().saveTestEntity(te);
		getFacade().saveTestEntity(te);
		getFacade().saveTestEntity(te);
	}

facade method:

@Transactional
	public void saveTestEntity(TestEntity entity)
	{
		getTestRepository().saveTestEntity(entity);
	}

repository method:

	public void saveTestEntity(TestEntity entity)
	{
		getGenericDAO().attach(entity);
	}

the genericDAO is either using JPATemplate or HibernateTemplate. both then use the corresponding *.merge(E entity) method

please note that the sessionfactory is using an IdTransferringMergeEventListener (the result in CASE 1 is not surprising but CASE 2 is)

CASE 1 with SESSIONFACTORY AND @Transactional on facade-method:

The entity just gets persisted one time.
hibernate output:

Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()
Hibernate: select testentity0_.id as ...
Hibernate: select testentity0_.id as ...

CASE 2 with SESSIONFACTORY and WITHOUT @Transactional on facade-method:

There are three records in the db (which i expected as normal behavior)

hibernate output:

Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()
Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()
Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()

CASE 3 with EntityManagerFactory AND @Transactional on facade method:

There are three records in the db.

hibernate output (same as in CASE 2):

Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()
Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()
Hibernate: insert into TestEntity (id, createdBy, createdOn, updatedBy, updatedOn, myEnum, name) values (null, ?, ?, ?, ?, ?, ?)
Hibernate: call identity()

CASE 4 with EntityManagerFactory and WITHOUT @Transactional on facade method:

nothing is done here by hibernate. no output and no persisted objects.

CASE 3 and CASE 4 behave like i expected them to, but i do not understand why HibernateTransactionManager does not need @Transactional and behaves kind of weird to me.

what are the differences here? it is really confusing me and i do not understand why it is behaving this way.
can anyone please help me out?

thanks a lot!
chris