| 摘要 |
PROBLEM TO BE SOLVED: To provide a distributed database system having a small operation constraint, high update performance, and high availability. SOLUTION: Using a database DB 1 having an update right of data as a root, a delivery tree obtained by coupling DBs 2-7 to a directed tree structure having the direction from the root to a leaf is created, the update result of the DB 1 is delivered toward the delivery tree by a bucket brigade method while keeping the update order in other database, and the contents of all DBs are kept identical. A first command for requiring the update right is delivered to the DB 1. After the DB 2 on the route connecting the DB 1 to the DB 3 for requiring the update right receives the first command, the direction (the direction of arrow) of the arc of the received delivery tree is inverted, the procedure of delivering the first command is repeated until it reaches the DB 3 having required the update right, thereby transferring the update right. Additionally, an operation of absorbing the difference of the update result is performed until the difference of the update result is eliminated. COPYRIGHT: (C)2008,JPO&INPIT
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