title: query execution duration is different for same queries in mysql even if cache is set to off
body: <p>I got different execution duration for the same queries even if the query cache is set to OFF. </p>
  
  <p>DATABASE that i'm using is MYSQL and Db Engine is InnoDB.</p>
  
  <p>Anyone please tell why this nondisciplinary duration happens for the same queries?.    </p>