A Multiversion Optimistic Concurrency Control Protocol in Mobile Broadcast Environments

Abstract

This paper presents MVOCC-MDA-2PV (multiversion optimistic concurrency control with multiversion dynamic adjustment using two-phase validation) protocol for processing mobile real-time transaction in mobile broadcast environments. Transaction validation is performed at two phases: pre-validation and final validation. At the mobile herts (MHs), all mobile transactions (MT) perform pre-validation of transactions by using backward validation mechanism. The pre-validation process is carried out against committed transactions at the server in the last broadcast cycle. Such an early data conflict detection feature can save processing and communication resources. Transactions that survive in pre-validation must be submitted to the server for final validation. The MHs do not need to synchronize with each other and servers for data conflict detection. The protocol can eliminate conflicts between mobile read-only and mobile update transactions, and resolve data conflicts flexibly using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. For a mobile ready-only transaction, it can be committed locally in the MH if it passes all the pre-validation in the course of it execution. Respond time of mobile read-only transactions (MROT) is greatly improved. The results of experiment show that the new protocol proposed offers better performance in terms of miss rate and commit rate.