Abstract: The concurrency in database system is a common phenomenon in multiuser environment where more than one transactions concurrently accessing the common data. Concurrency can lead to an adverse effect on database if it is not efficiently controlled. In the past many people have addressed the problem of concurrency and also suggested and proposed various concurrency control methods. The scope of this study involves study and comparative analysis of basic concurrency control methods that can be classified as either pessimistic or optimistic. Different protocols exhibit good performance on different situations, some methods prefers locking approach while others are based on time stamp. In this work we have studied basic concurrency control methods of both pessimistic and optimistic approaches, highlighting their pros and cons. At last study shows the comparative analysis of basic concurrency control methods.
Keywords: CC, PCC, OCC, 2PL, S2PL, TIMESTAMP, TO, BOCC.