A new multiversion concurrency control algorithm for partial update transactions and bulk retrieval transactions

With the advanced use of databases, on-line and batch transactions are executed concurrently. Then a demand arose for the concurrency control method which can realize the excellent on-line transaction processing independently of the batch transactions. The multiversion concurrency control is suitable for such a requirement. This paper proposes a new multiversion concurrency control algorithm which has a high concurrency between the partial update transactions, which is a typical on-line transaction, and the bulk retrieval transactions, which is a typical batch transaction. The algorithm is based on a mixture of an improved two-version, two-phase locking and the multiversion time stamp ordering. It is shown as simulation results that the proposed algorithm is better than the traditional ones in terms of the completion ratio of the partial update and the completion ratio of the bulk retrieval, independently of the number of partial updates executed concurrently. It is shown also that the algorithm is better than the traditional ones in such an environment since the data contention between partial update transactions is high.