| 摘要 |
PROBLEM TO BE SOLVED: To prevent redundancy from being lost.SOLUTION: An each database device includes: a flag storage part 11 which, when it is a master, stores a completion flag storing whether or not submission of a replication request to a slave database device is completed in exchanging masters; transmission means 14 which, when the master is changed to a slave, transmits data of the completion flag to a database device to become a master anew; and means which, when the slave is changed to the master, determines whether or not synchronization is completed by transmitting all data stored to its own device or without transmitting any with respect to a replication start request from the slave database device on the basis of data of the completion flag received from the former master database device. |
