PRECEDENCE-ASSIGNMENT MODEL FOR DISTRIBUTED DATABASE CONCURRENCY CONTROL ALGORITHMS.

We have developed a unified model, called the precedence-assignment model (PAM), of concurrency control algorithms in distributed database. It is shown that two-phase locking, timestamp-ordering and other existing concurrency control algorithms may be modeled by PAM. We have also developed a new concurrency control algorithm under the PAM modeling framework, which is free from deadlocks and transaction restarts. Finally, a unified concurrency control subsystem for precedence-assignment algorithms is developed. By using this subsystem, different transactions may be executed under different concurrency control algorithms simultaneously.link_to_subscribed_fulltex