A New Protocol to Optimize the Degree of Concurrency in Object-Oriented Databases

D. Saha and J. Morrissey (Canada)

Keywords

ObjectOriented systems, concurrency control, locking,performance of locking protocols

Abstract

Unlike relational databases, Object-Oriented Databases (OODBs) can provide persistence for object-oriented applications without using an object-relational mapping layer. Object databases are being used more because of the availability of open source object databases. They are widely affordable and easy to use, because they are written entirely in OOP languages. With the increased use of OODBs, there is a pressing need to find an appropriate concurrency control protocol for them. However, little or no research has been done on this issue recently. This paper proposes an Extended Adaptive Multi-granularity Locking protocol (XAMGL), for OODBs. It picks an appropriate locking granularity according to the requirements of the transaction. Furthermore, it has less overhead and provides better concurrency compared to some existing protocols. There is another adaptive multi granularity protocol, AMGL [2], which provides the same degree of concurrency as XAMGL. However, our protocol significantly reduces the number of locks used which is important because it frees up locked data more quickly for all transactions. Experimental and analytical results show that XAMGL performs best when the workload in the system is high and transactions are long lived, which happens frequently in object-oriented applications.

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