Patent ID: 8762354

Claim:
A database management method of a lower-level master node in a recordable database hierarchically including higher-level and lower-level master nodes, comprising: generating, by a database processing unit of any one of lower-level master nodes, for a higher-level master node, a write set expanded in a memory for the database processing unit, including a shadow copy of a database and a heap tuple map, when an instruction for updating the database is issued in the lower-level master node, sending the write set to the higher-level master node for causing the higher-level master node to compare the heap tuple map in the write set received from the lower-level master node and the database of the higher-level master node, to verify whether a corresponding row of the database registered as a target has been updated by a different write set, to abort the write set when the update has been performed, to update the database of the higher-level master node using the shadow copy when the update has not been performed, to generate a record of this update as a transaction log, and to distribute the transaction log to the lower-level master nodes including the lower-level master node which has sent the write set; and updating, by a transaction log processing unit of the lower-level master node, upon receiving the transaction log, the database of the lower-level master node based on the received transaction log.