A NEW TYPE-SPECIFIC CONCURRENCY CONTROL ALGORITHM

Abstract

The work of this thesis has been mainly motivated by the advantages of using the serial dependency as a conflict relation which is weaker than the commutativity relation.. We propose a new type­ specific concurrency control algorithm which uses serial dependency as a conflict relation. Unlike the pessimistic concurrency control algorithms in literature,which use a symmetric serial dependency relation, the proposed algorithm uses an asymmetric serial dependency relation. It distinguishes symmetric and asymmetric conflicts and uses this information to improve the level of concurrency .

Performance analysis of algorithms that use the serial dependency relation are not presented in the literature. Consequently , one of the objectives of this study ,was to propose an approximate analytical model to obtain bounds for the performance of the proposed algorithm relative to the related algorithms proposed in literature.

An analytical model was formulated to obtain bounds for the performance of the studied algorithms. The proposed analytical model is based on the mean value approach.

A simulation model was constructedJ verified and validated. Then,the approximations of the proposed analytical model were validated by comparing the results obtained from the analytical solution to those obtained from the corresponding simulation runs .

Finally,several parametric studies were conducted using the validated analytical model to compare the performance of the proposed algorithm to the related type-specific algorithms