title: difference between del() and flushAll() of jedis
body: <p>I am new to jedis. I am not able to distinguish del() and flushAll(). Does del() deletes the keys from cache or from database. Kindly provide some details. 
  Please note, I did try to search for an answer on the web, but could't fine my answer.</p>
  
  <p>Thank you.</p>