ABSTRACT
A database is a collection of data objects organized especially for rapid search and retrieval. Distributed data management issues of special interest include: synchronization of access to shared data while supporting a high degree of concurrency and making data resilient to failures in the system. In a database system a data model provides a way in which the stored data is organized for quick retrieval or other purposes. A database management system is a software system that permits the management of the database. A database system is distributed if its data is dispersed among different physical locations. One goal in distributed data management is to provide a systematic way to execute concurrent transactions in such a manner that their schedule is serializable. One of the most popular concurrency control mechanisms is the lock-based, scheme, which inserts a set of lock and unlock statements in each transaction without providing explicit scheduling.
