Does HQL ,Criteria Query checks Session Cache

khangharoth · **Joined:** Fri Aug 31, 2007 11:58 am **Posts:** 19

I tried to search this on forum but was unsuccesful so posting as new question.
I know SQL query always get fresh result from Db rather than checking for dirty objects in Session.What about HQL query and Criteria Query.

mmerder · **Posted:** Tue Feb 17, 2009 10:39 am

Criteria and HQL query also use session cache, but they DO a query on the database. Before hydrating the resultset to the fetched data it is checked, whether these objects have already be loaded. This is important to achieve "==" equality within a session:

Code:

        Customer customer = session.get(Customer.class, 1L);

        Query q = session.createQuery("from Customer c where c.id = :id");
        q.setParameter("id", 1L);
        
        //true
        System.out.println(customer == q.uniqueResult());
        //true
        System.out.println(customer == session.createCriteria(Customer.class).add(Restrictions.idEq(1L)).uniqueResult());

Also notice that the session is flushed before querying, so that there would be no dirty objects in a session.

khangharoth · **Joined:** Fri Aug 31, 2007 11:58 am **Posts:** 19

If that's is the case then i am getting unexpected result.
I am doing following steps
a) Creating a Hibernate enitity and Saving it.
b) Modifying it.
c) Fetch it on the basis of id by Criteria query.

Its giving me the object in Db rather than modified object.If i do commit before fetching then i get modified object.This behaviour has confused me about how Criteria query behave.

mmerder · **Posted:** Tue Feb 17, 2009 11:18 am

What do you mean with: "If i do commit before fetching then i get modified object"? I mean, in both cases your modified object is your "db-objects", because if you do not commit explicitly the session is flushed anyway.

How do you determine which object you get? Could you post you testcode?