Database Management Systems are in near universal use by a wide variety of commercial, industrial, military, and other organisations. DBMS are entrusted with data that is vitally important to organisational users, which must be kept safe. The module is concerned in part with four safety mechanisms that DBMS contain. A Recovery mechanism ensures that after any unanticipated failure of software or hardware, a database can be restored to a useful consistent state. A Concurrency mechanism ensures that multiple simultaneous use of a DBMS is possible without interference between independent tasks. A Security mechanism ensures control over what operations on a database users and their programs may perform. An Integrity mechanism ensures that no user or program can corrupt a database by rendering it inconsistent or meaningless. The module is concerned in part also with the aims, advantages and challenges of distributed databases, and with alternatives to the standard Relational data model, particularly in Object-Oriented databases.
