Abstract: In a shared
database system when several transactions are executed simultaneously, the consistency
of database should be maintained. The techniques to ensure this consistency are
control techniques. All concurrency-control schemes are based on the serializability property. The serializability
properties requires that the data is accessed in a mutually exclusive manner;
that means, while one transaction is accessing a data item no other transaction
can modify that data item.
In this paper we
had discussed various concurrency techniques, their advantages and
disadvantages and making comparison of optimistic, pessimistic and multiversion techniques. We have simulated the current
environment and have analysis the performance of each of these methods.