Abstract: A database processor in a distributed database system has a decision making section for use in detecting whether a distributed deadlock has occurred if a contention is detected by a contention detector. If a distributed deadlock occurs, the decision making section posts or provides a concurrency controller with information regarding the detection of the distributed deadlock, whose occurrence has been detected by a global deadlock detector on a network to which the database processor is connected. The concurrency controller instructs a transaction controller to cancel the queuing of the transaction forming the distributed deadlock. The transaction controller can then take prescribed controlling actions to swiftly resolve the distributed deadlock.

Abstract: A database processing device executes concurrent processing in accessing a database through a plurality of independent terminal units. The database processing device, upon updating data stored in a record after reading out the data stored in the record in the database and correcting or altering the data through a specific terminal, confirms whether or not the data stored in the record has been updated by terminals, and executes updating only when the data has not been updated. The data stored in the record includes update control information for confirming whether or not the data has been updated by other terminals.