title: FindAndModify Atomic Query
body: <p>i have read about FIndAndModify:</p>
  
  <p><a href="http://www.mongodb.org/display/DOCS/findAndModify+Command" rel="nofollow">http://www.mongodb.org/display/DOCS/findAndModify+Command</a>:
  <strong>this command can be used to atomically modify a document (at most one) and return it.</strong></p>
  
  <p>This means that the locking is at level of Document, Collections, Database?</p>
  
  <p>I think Document, but in other post I have read Database.</p>
  
  <p>da.</p>