The Database Administrator, better known as DBA, is the person (or a group of persons) responsible for the well being of the database management system. S/he has the flowing functions and responsibilities regarding database management:
- Definition of the schema, the architecture of the three levels of the data abstraction, data independence.
- Modification of the defined schema as and when required.
- Definition of the storage structure i.e. and access method of the data stored i.e. sequential, indexed or direct.
- Creating new used-id, password etc, and also creating the access permissions that each user can or cannot enjoy. DBA is responsible to create user roles, which are collection of the permissions (like read, write etc.) granted and restricted for a class of users. S/he can also grant additional permissions to and/or revoke existing permissions from a user if need be.
- Defining the integrity constraints for the database to ensure that the data entered conform to some rules, thereby increasing the reliability of data.
- Creating a security mechanism to prevent unauthorized access, accidental or intentional handling of data that can cause security threat.
- Creating backup and recovery policy. This is essential because in case of a failure the database must be able to revive itself to its complete functionality with no loss of data, as if the failure has never occurred. It is essential to keep regular backup of the data so that if the system fails then all data up to the point of failure will be available from a stable storage. Only those amount of data gathered during the failure would have to be fed to the database to recover it to a healthy status.