I am running a job which deletes data from 7 tables, 2 of which contains 10-20 lakhs of records. But the job get stuck at a point when deleting data from a particular table web_activity which holds only 42000 records. It takes 4 hours most of the times. But sometimes it takes only 7 minutes. If this is the issue of index then what happens on the day of 7 minute execution.