KRISHNA - An Efficient Concurrency Control Algorithm Based on Dynamic Attributes of Transactions and its Performance

Concurrent transactions during their execution life acquire a number of attributes. We call them dynamic attributes of transactions. We have used them to develop a concurrency control mechanism, called KRISHNA, using two-phase locking policy. To establish the usefulness of dynamic attributes in developing concurrency control mechanisms and to investigate the behavior of KRISHNA, we have studied their performance using a detailed simulation model. We show that KRISHNA outperforms a number of well-known concurency control mechanisms based on two-phase policy. We also show that the conflict resolution policy of KRISHNA is comparatively more accurate in resolving conflicts, i.e., it selects the "right" transaction for rolling-back or blocking. We argue that implementing KRISHNA is not expensive compared to commonly used concurrency control mechanisms.