title: Can I use two related objects as composite key in Doctrine bundled with Symfony2?
body: <p>Object is ArticleVote and it has two related objects: User and Article. This creates user_id and article_id columns in ArticleVote table. Can I go without using "id" as an id of the table and use a composite key that consists of unique combinaiton of user_id and article_id in ArticleVote talble?</p>
  
  <p>Also, is this supported in Doctrine bundled with Symfony2?</p>
  
  <p>Thanks.</p>