Tadamitsu Ryu

Database system having a plurality of nodes communicating with each other via communication network

A database system includes a communication network, and a plurality of nodes. Each node includes a data storage device, a management part managing a status of the data stored in the data storage device, and a data storage request part for generating an alternative data storage device assignment request for requesting at least one of other nodes among the plurality of nodes to store data in the data storage device of the other node via the communication network when a predetermined condition is satisfied. A determining part receives the alternative data storage device assignment request from a request node which generates the alternative data storage device assignment request and assigns a storage area in the data storage device for storing data related to the alternative data storage device assignment request by referring to the status of the data managed by the management part when the data storage device of the other node has an enough storage capacity to store the data related to the alternative data storage device assignment request.