A multi-version concurrency scheme with no rollbacks

Abstract

The multi-version data item concept is a method for increasing concurrency in a database system. All previously proposed schemes utilizing this concept relied on transaction rollback as a means for preserving consistency. These rollbacks require a considerable amount of overhead which degrades performance. In this paper we develop a new scheme that utilizes the multi-version data item concept. Our proposed scheme ensures consistency without the use of rollbacks. It is based upon the non-two phase tree locking protocol previously proposed by Silberschatz and Kedem.