title: How to handle in an effective way duplicate key insertions w/out throwing an exception
body: <p>My case scenario passes parameter to a procedure, that only does an insert. But two threads might try to pass the same value. </p>
  
  <p>How to handle this situation w/out throwing an exception and with least amount of locks?</p>
  
  <p>My performance requirement is at least 10k inserts per second.</p>
  
  <p><strong>EDIT:</strong> Column is unique. Timestamp might be altered (adjusted) before insertion.</p>