Qual a melhor forma de conectar um segundo banco de dados somente para consulta

public class HibernateUtil {

    private static final HashMap<String, SessionFactory> sessionFactory = new HashMap<String, SessionFactory>();
    private static ServiceRegistry serviceRegistry;

    static {
        try {
            HibernateUtil.configureSessionFactory();
        } catch (Throwable ex) {
            // Log the exception. 
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    private static void configureSessionFactory() throws HibernateException {
        Configuration configurationPostgre = new Configuration(), configurationOracle = new Configuration();

        configurationPostgre.configure("hibernate.cfg.xml");
        configurationOracle.configure("hibernate_oracle.cfg.xml");

        serviceRegistry = new ServiceRegistryBuilder().applySettings(configurationPostgre.getProperties()).buildServiceRegistry();
        sessionFactory.put("postgre", configurationPostgre.buildSessionFactory(serviceRegistry));

        serviceRegistry = new ServiceRegistryBuilder().applySettings(configurationOracle.getProperties()).buildServiceRegistry();
        sessionFactory.put("oracle", configurationOracle.buildSessionFactory(serviceRegistry));
    }

    public static SessionFactory getSessionFactory(String db) {
        //Aqui você pega de acordo com o que usou de chave, "postgre" ou "oracle"
        return sessionFactory.get(db);
    }