This is a kind of a late response to this thread but you can use a coalesce function: coalesce(from_unixtime(unix_timestamp(dob ,"MMM dd, yyyy"), "dd/MM/yy"),from_unixtime(unix_timestamp(dob ,"MM/dd/yyyy"), "dd/MM/yy"), from_unixtime(unix_timestamp(dob ,"MM/dd/yy"), "dd/MM/yy)) as new_dob ... View more

Check the size of the file if it is zero bytes then it means there is some corruption with that particular FSImage file. Instead of formatting the namenode which will result in complete data loss, you can just manually remove the FSImage file and then start your namenode with minimal damage to your cluster. ... View more