SessionFactory initialization

pedromendessk · **Joined:** Mon Jun 24, 2013 7:58 am **Posts:** 1

Hi!

I've been developing with Hibernate for a while and have just now been faced with this question,

What is the best approach to open the Session Factory? Open it when the application starts? Or for each set of instructions in the database?
Well, I ask this because I've been opening it for each set of instructions.

For example, when I want to list some data I do the following (Only map the necessary tables)

Code:

Configuration configuration = new Configuration()         
    .addAnnotatedClass(table1.class)
    .addAnnotatedClass(table2.class)
    .addAnnotatedClass(table3.class)
    .configure();

serviceRegistry = new ServiceRegistryBuilder().applySettings(hibConfiguration.getProperties()).buildServiceRegistry();
sessionFactory = hibConfiguration.buildSessionFactory(serviceRegistry);
session = sessionFactory.withOptions().openSession();

In the Hibernate documentation they say "A SessionFactory is set up once for an application". This would mean that all the tables will be added to the Session Factory on the application start right? Or will be set in the Hibernate.cfg.xml and for consequence will be loaded on the application start.

But does this applies to big databases? My application database has about 150 tables. Wouldn't it be to much heavy?

What do you advice?

Thanks in advance :)

sathish.kannan · **Joined:** Sat Jul 27, 2013 1:47 am **Posts:** 5

It wont be heavy. Only Configurations will be loaded. None of the data is going to be loaded.

So it is always a good practice to have one SessionFactory for an application and it has to be initialized on startup.

bsanders1979 · **Posted:** Sun Jul 28, 2013 5:30 pm

You don't "open" a SessionFactory. As the name implies, it's a Factory which produces Session objects. The Session is what you open to get the data. What you probably want to know is if you should use Session-Per-Operation, or Session-Per-Application and the answer is neither. Read up on the Session-Per-Request pattern.

Ajit Singh · **Joined:** Wed Feb 06, 2013 2:43 am **Posts:** 46

Exactly. There should be only one sessionFactory.

I have around 500 tables and it works good.
And it is not going to load all the Data from those tables. It just loads the structure of tables.