 The original "dbm" library and file format was a simple database engine, originally written by Ken Thompson and released by AT&T in 1979.The name is a three letter acronym for "DataBase Manager", and can also refer to the family of database engines with APIs and features derived from the original "dbm".The "dbm" library stores arbitrary data by use of a single key (a primary key) in fixed-size buckets and uses hashing techniques to enable fast retrieval of the data by key.