Optimistic Concurrency Control Algorithm with Dynamic Serialization Adjustment for Firm Deadline Real-Time Database Systems
A new optimistic concurrency control algorithm for firm deadline real-time database systems is presented. The algorithm dynamically adjusts a serialization order among conflicting transactions and, thus, tries to reduce the number of unnecessary restarts of transactions. Instead of aborting a lower priority transaction being in conflict with already committed higher priority transaction the algorithm is looking for a new serialization order, i.e. it tries to serialize the transaction before the conflicting one. Through simulation experiments, we evaluate the performance of the algorithm, and compare the algorithm with two well-known optimistic concurrency control algorithms: OCC and OPT-BC. Experimental results have shown that the performance of the algorithm depends on a system workload. The probability of successful reordering of conflicting transactions decreases with the increasing number of conflicts between the transactions.
KeywordsSerialization Order Concurrency Control Execution Order Read Phase Concurrency Control Mechanism
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