Abstract:Database is the collection of files or table and Database Management System is used to manage the overall activities of the database. We have two approaches for storing and managing database namely Centralised Database management system and Distributed Database management system. Query Processing and its optimization is one of the major key areas of Distributed Database Systems. Query optimization is much more difficult in Distributed Database as compared to the Centralised Database System. This literature review paper is based in the query optimization in Distributed Database System. It mainly focused on to analyse the performance and behaviour of the use of semi-joins and joins. Various factors are considered like CPU cost, I/O cost, Total Cost, Response time and Total time etc. Minimizing the amount of data transmission is important to reduce the query processing cost. To minimize this communication cost, the exhaustive enumerative technique has used to bring dynamism in determining the sub operations (join or semi join) to various sites.