It offers an effective way to organize data while there is a requirement to access individual records directly.
To access a record directly (or random access) a relationship is utilized to translate the key value in a physical address. It is called the mapping function R.
R(key value) = Address
Direct files are stored onto DASD (Direct Access Storage Device).
A calculation is carrying out on the key value to get an address. This address calculation technique is frequently termed as hashing. The calculation applied is called hash function.