code: def update(bucket)
  			@queries['update'].execute(bucket.current, bucket.last_refill, bucket.total_used, bucket.name)
  		end
docs: updates the key fields that need updating into the storage
   this is often cheaper for certain types of storage than using set()
   * *Args*    :
     - +bucket+ -> the Bucket to update.  The <tt>name</tt> field in the Bucket option will be used as a key.
   * *Returns* :
     - an empty result set
   * *Raises* :
     - +Mysql::Error+ -> any issue with the connection to the database or the SQL statements