title: Upgrade of Hibernate from version 3.0 to 3.6
body: <p>I'm working on a project which uses <code>Hibernate 3.0</code>(released in 2005), though the project itself is only 4 months old. The catch is we have already written millions of lines of code. We realized we are using <code>Hibernate 3.0</code> only yesterday and now we badly want to move to the latest stable release <code>3.6.6</code>.</p>
  
  <p>So I want to know:</p>
  
  <ul>
  <li>Will there be a lot of changes in the way we map hbm files?(and properties file)</li>
  <li>Are we likely to get major improvement in performance?(currently we are having some performance issues due to Hibernate's badly formed queries)</li>
  <li>Will there be a lot of changes in the way we write HQL?(we are using HQL heavily)</li>
  </ul>
  
  <p>Appreciate your help.</p>