A New Commit Protocol for Distributed Real-Time Database Systems

U. Shanker, M. Misra, and A.K. Sarje (India)


Dependencies, conflict, commit dependency, coordinator, cohort, abort dependency


Although there are several factors contributing to the difficulty in meeting distributed real time transaction deadlines, data conflicts among transactions, especially in commitment phase, are prime factor resulting in system performance degradation. Therefore, design of an efficient commit protocol is of great significance for real time database system (DRTDBS). This paper first analyzes all kind of dependencies that may arise due to data access conflicts in executing-committing transaction and, then proposes a new commit protocol. Most of the existing commit protocols try to improve the system performance by allowing a committing transaction to lend its data to an executing transaction, thus reducing data inaccessibility. These protocols block the borrower when it tries to send WORKDONE/ PREPARED message ([1], [5], [7]). The proposed protocol allows the borrower to send WORKDONE message when it completes execution. This reduces the time needed for commit processing. Moreover the borrower can not be aborted by a higher priority transaction once the borrower gets the request for the vote message from its coordinator. Simulation results show that the proposed protocol improves the system performance.

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