title: unique constraint violated error performance
body: <p>I am inserting in a table millions of records , such operation will need  hours or maybe a day. After 2 hours the connection through my pc was disconnected, so I want to repeat the insert from the start.<br/>
  <b>My Question</b><br/>
  which is faster ? truncate the table and repeat it again , <b>or</b> creating a primary key and continue, however an error will be raised because of 'unique constraint violated' for every record that was inserted in the last 2 hours.</p>