Multi-scheduler Concurrency Control for Parallel Database Systems

Increase in amount of data stored and requirement of fast response time has motivated the research in Parallel Database Systems (PDS). Requirement for correctness of data still remains one of the major issues. Concurrency control algorithms used by PDS uses single scheduler approach. Single scheduler approach has some inherent weaknesses such as – very big lock tables, overloaded centralized scheduler and more number of messages in the system. In this paper we investigate the possibility of multiple schedulers and conclude that single scheduler algorithms cannot be migrated in the present form to multi-scheduler environment. Next, we propose a Multi-Scheduler Concurrency Control algorithm for PDS that distributes the scheduling responsibilities to the respective Processing Elements. Correctness of the proposed algorithm is then discussed using a different serializability criterion – Parallel Database Quasi-Serializability.