Concurrency control is a method of managing multiple transactions or operations that are running simultaneously. It occurs in the multiuser system, where more than one user executes some transaction at the same time. Executing any transaction simultaneously will lead to inefficient system performance, very high waiting time and response time, and decrease resource utilization without concurrency control. The transaction processes are made in a very large database, and thousands of concurrent users are executing the database transaction at the same time.
Let us suppose 1000 users are trying to perform some online banking or ATM transaction. So without concurrency, all the transaction takes too much time to process, or it may also be possible that they won’t be able to perform the transaction, and the integrity is not maintained without concurrency. In this situation, the transactions are also conflicting and not maintaining any consistency will also lead to failure to processed transactions.
The concurrency control method ensures the transactions to, be concurrent, accurate, and give correct results without violating data integrity. It preserves database consistency and provides data isolation between conflicting transactions. It also ensures serializability. It also reduces the waiting time and response time of the system and enhances resource utilization which further enhances the efficiency and system performance.