Load the index into RAM for use in file access 3. Retrieve record by key 4. Add a record to the file and update the index 5. Delete a record from the file and update the index 6. Change a record and update the index.
Late binding allows secondary indexes to be left unchanged by a deletion.
A secondary index may be on a non-unique key The above secondary indexes have redundant instances of the index key. We can improve things by including each index key value just once in the index and have the value associated with a list of the appropriate primary keys. Now, with several secondary indexes there are redundant occurrences of primary keys.