An Improved Distributed Real-time Transaction Scheduling Protocol
LIU Bo-1, FAN Shi-ming1, CONG Hong-yan2
1(Beijing Institute of Satellite Information Engineering, Beijing 100086, China) ,2(China Key Systems & Integrated Circuit Corporation, Wuxi 214072, China)
Abstract：Distributed real-time transaction scheduling protocol which used to isolate the interference of concurrent transactions, is needed to achieve consistency and isolability requirements of transaction. On the base of optimistic concurrency control protocol which employ timestamp interval to dynamically adjust serialization order between transactions, an improved distributed real-time transaction scheduling protocol which is divided into reading phase, waiting phase, preparing phase and commit phase is proposed. In reading phase and waiting phase, the serialization order of transactions is dynamically adjusted based on their priorities. High priority transaction is allowed to enter validation phase earlier and the unnecessary restart of transactions is avoided by blocking low-priority transactions. Prepared data would be inaccessible for a long time in distributed environment which would block transaction, so transaction in preparing phase is allowed to lend data to low-priority transaction. In order to avoid blocking because of single failure, paxos commit protocol is employed for distributed real-time transaction commit. The proposed method has shown an excellent result in one simulated environment.
