Towards a General Concurrency Control Algorithm for Database Systems

The concurrency control problem in database systems has been examined by many people and several concurrency control algorithms have been proposed. The most popular algorithms are two-phase locking and timestamp ordering. This paper shows that two-phase locking and timestamp ordering are special cases of a more general concurrency control algorithm. This general algorithm is described in detail and is proven to work correctly. We show that two-phase locking and timestamp ordering represent the two end points of a series of concurrency control algorithms. Each of them is a special case of the general algorithm proposed in this paper. Moreover, each of these special cases can be selected in advance, and can even be changed dynamically during execution.