Performability management in distributed database systems: an adaptive concurrency control protocol

An adaptive concurrency control protocol is proposed for distributed database systems where data and resource contention have adverse effects on performability. The protocol dynamically switches between two existing concurrency control mechanisms, namely, an optimistic one called the “exclusive writer with locking option” and a pessimistic one referred to as “primary site locking.” Adaptation is based on partial knowledge about the system that is available locally at any database site such that no overhead (no additional inter-database site message exchange for collecting information) is incurred. The evaluation results indicate a potential for significant gains in performability from the use of adaptive concurrency control techniques