System for scheduling database transactions distributed over a network

Abstract

A database management system has a plurality of nodes each having a computer, a database and a clock. The nodes are interconnected by a communication line. Each database stores a plurality of data for processing. When a transaction request is generated at a first node, a transaction management section of the first node computer determines which node database(s) includes necessary data for executing the transaction. A maximum delay decision section of the first node computer determines the maximum delay for sending an instruction to all of the nodes having necessary data. A locktime decision section of the first node computer determines a locktime according to the maximum delay determined and the current time of the clock. Then, a transaction management section of the first node computer sends the locktime through the communication line as a lock instruction to the node(s) having the necessary data. A scheduler section of the computer in the node(s) having the necessary data receives the lock instruction sent by the transaction management section of the first computer. An associated lock activation section activates the scheduler section when the locktime coincides with the current time of the clock. The scheduler section locks the necessary data in the database in response to activation by the lock activation section.