Hibernate version: 3.0

Name and version of the database you are using: MySQL 4.1



Hi,

I am considering to use Hibernate for our J2EE application but have one question. Our application dynamically generates databases during runtime, which need to be accesible without a restart. Does hibernate allow for this, and does it thus allow dynamic updates of the hibernate.cfg.xml file?

Thank you,

Yes, you can reload the configuration with new objects. You don't need to use the hibernate.cfg.xml, there are classes in the framework to load new mappings.
It's possible to be done. But I haven't done it b4.
But it may require some testing, if this process of table change happens too often, you may get some performance problems. Using or not using hibernate.

Max a couple of times a week, so I don't think performance should be too much of a problem, right?

You mention "process of table change". What do you mean by this as I'm inquiring about database creation, not table creation.

Thank you,

Sorry, you are just changing the database and not the table schema?
If it's a distinct vendor (like Mysql to Postgres) you have to change the translator. If it's just connection, you can build the session passing connections as parameter.
And even if you have distinct tables and databases it's still possible to do, but may require some extra work. You may have to work with different classes to different database structure.

I had a similiar issue in my swing app where the user had to select a particular database/schemata/catalog (different databases use different terminology here) within mySQL.

I used a helper class that dynamically assigns the connection url, passing it the name of the database to use.


Relevant code:

//HibernateHelper Constructor
public HibernateHelper(String dbName)
{
String connectURL = "jdbc:mysql://localhost/" + dbName;
sessionFactory= new Configuration()
.setProperty("hibernate.connection.url", connectURL)
.configure()
.buildSessionFactory();
}



//In main app

HibernateHelper hh = new HibernateHelper("name_of_database_to_use");
Transaction trans = hh.getSession().beginTransaction();

// do stuff here,

trans.committ();

Is it possible, or wise, to use multiple SessionFactories within your app. I don't know, but I hope this helps.

spovilaitis,

Thanks! Very usefull.

Regards,
Joost