Direct access is used to retrieve, update, delete and add records. When direct processing is used, VSAM searches the index from the highest level index-set record to the sequence-set for each record to be accessed. Searches for single records with random keys is usually done faster with direct processing. You need to supply a key value for each record to be processed.

For retrieval processing, either supply the full key or a generic key. The generic key is the high-order portion of the full key. For example, you might want to retrieve all records whose keys begin with the generic key AB, regardless of the full key value. Direct access lets you avoid retrieving the entire data set sequentially to process a small percentage of the total number of records.