title: Symfony 2: How to avoid the sessions table being dropped by doctrine migrations?
body: <p>I'm new to migrations, and I'm trying to stick to the automatically generated ones:</p>
  
  <pre><code>$ php app/console doctrine:migrations:diff
  $ php app/console doctrine:migrations:migrate
  </code></pre>
  
  <p>The problem is that this drops my sessions table. What can I do to avoid that?</p>