Record Deletion in multiple key access settings
Removing a record from the data file means removing its corresponding entry in the primary index and may mean removing all of the entries in the secondary indexes that refer to this primary index entry.
However, it is also possible not to worry about the secondary index (since, as we mentioned before, secondary keys were made to point at primary ones). ==> savings associated with the lack of rearrangement of the secondary index.
Cost associated with not purging the secondary index.