Updating Process

Both the master file and transaction file are read

(1) The keys are then compared.

(2) If the master file key is less than the transaction file key, no change is required. The record is copied to the new master file.

(3) If the master file key is equal to Transaction file key, then the record is to be either deleted or modified.

(4) If the master file key is greater than transaction file key, then it means that the transaction file record is new and is therefore to be copied to the new master file.

(5) Three generations of files are maintained always. Hence the name Grandfather-father-son update.