title: Spring unique ID as integer with excatly 9 digits - not sequence
body: <p>I am trying to find best practise to generate <code>id</code> of <code>Entity</code> in <code>Spring</code>
  with following requirements:</p>
  
  <ul>
  <li>has to be unique</li>
  <li>has to have 9 digits</li>
  <li>has to be int</li>
  <li>can not be sequence</li>
  </ul>
  
  <p>I can not use <code>uuid</code> cause it does not follow requirements.</p>
  
  <p>I am using <code>Hibernate</code> currently version 4.3.1 - but probably i could update if needed.</p>