Distributed data base system of composite subsystem type, and method of

Abstract

In a composite subsystem having a plurality of data base systems and data communication on a plurality of processors, a composite subsystem controller unifies other data base systems of the composite subsystem and distributed data base systems, and, at the occurrence of a fault in some subsystem, allows other subsystems to operate continuously, thereby facilitating the recovery after the faulty subsystem has started up, and makes management as to which data base system a transaction in execution has accessed so that the range of failure is confined, thereby facilitating the fault recovery. The check points of two processings including updating of information in the memory and accumulation of the updated information in the journal are detected so that the need of journals earlier than the check point is eliminated, and a check point dump is acquired without waiting for the end of transaction which has been active at the check point.