Why sometimes the transaction is required for query, sometimes the transaction is not required?
Where and what is the logic for that?
In my opinion the transaction is not required for any query, but today I use Oracle 10g where was impossible to make Query without transaction:
public static List<Order> getOrders()
{
Session session = getSessionFactory().getCurrentSession();
Transaction transaction = session.beginTransaction();
try
{
List<Order> orders = (List<Order>)session.createQuery("from Order").list();
transaction.commit();
transaction.begin();
return orders;
}
catch(Throwable ex)
{
transaction.rollback();
session.close();
ex.printStackTrace();
throw new RuntimeException(ex);
}
}

I am looking in other projects which use MySQL and Derby where the transaction is not required for query.
Now I am trying to make the same situation for Derby but the query is processing fine without transaction.

Can somebody tell me where is the true and is it possible to configure Hibernate when use Oracle to make Query without using transactions?


Thank you in advance.


Miro.

http://hibernate.org/42.html _AND ALL LINKED PAGES_.

I read this few times and can not understand why the same code with Query one time can be executed without Transactaion, and for Oracle I need of transaction.

The transaction is OK for Update and Save, but for Query ???

Because you don't understand the auto-commit mode.

http://www.hibernate.org/403.html

I try to reproduce the problem using Derby database using AutoCommit with TRUE and FALSE values, but in both cases the Query works without BeginTransaction requirement.
Maybe I am stupid and need of more clarifucation. Could you be so kind to explain me why for Derby I do not need of Begin Transaction for any kind for query, but for Oracle I need?
Can I control this behaviour of Hibernate?

Just for your information I have your book (Dec-2006) and I can not find information for this case inside.

Why do you begin the transaction twice?

Forget for this example. These are some tests.
The right working examples are:

1. Orcale:
Session session = getSessionFactory().getCurrentSession();
Transaction transaction = session.beginTransaction();
session.createQuery("from Order").list();

2. Derby:
Session session = getSessionFactory().getCurrentSession();
session.createQuery("from Order").list();


When I try to make Oracle Query without transaction I have Hibernate Exception.