Semantic multigranularity locking for transaction management in object-oriented database management systems : MGL/IS

Abstract

Concurrency control schemes for OODBMSs used in the area of performance-critical applications should increase the degree of concurrency and decrease locking overhead in order to offer maximum throughput and minimum response time. In OODBMSs, there is an opportunity for enhancing the degree of concurrency by way of exploiting semantics of methods defined on classes. Most commercially available OODBMSs, however, use conventional concurrency control schemes which never exploit the rich semantics of object-oriented data model, so that they miss the opportunity to offer better performance. In this thesis, we propose a concurrency control scheme for OODBMSs, called in-place semantic multigranularity locking, MGL/IS for short, and evaluate its performance. MGL/IS not only exploits semantics regarding methods to enhance the concurrency degree, but also utilizes multigranularity locking rules to decrease locking overhead. The novel aspect of MGL/IS is that it combines conventional multigranularity locking and nested transaction model with utilizing commutativity of methods. In addition, MGL/IS is applicable for realistic OODBMSs in the presence of complex objects with shared subobjects.