Strange behaviour of a query with order by and rownum on Oracle's Exadata server
This answer  is wrong, because the value for rownum is assigned before the order by is executed. 

Below is the correct one,

SELECT start_date,  
       end_date,  
       resort_id,  
       ROWNUM  
FROM   (SELECT   start_date,  
                end_date,  
                resort_id  
       FROM     employee_activity  
       WHERE    employee_id = 27  
       AND      start_date &lt; TO_DATE ('2012-11-09', 'YYYY-MM-DD')  
       AND      is_overridden = 1  
       ORDER BY start_date DESC
      )  
WHERE  ROWNUM = 1