title: Django partial update
body: <p>I have two threads, one which runs something like <code>update t set ColA=foo</code> and the other runs <code>update t set ColB=foo</code>. If they were doing raw SQL statements there would be no contention, but since Django gets and saves the entire row, a race condition can occur.</p>
  
  <p>Is there any way to tell Django that I just want to save a certain column?</p>