Concurrency Control and Problems Due to concurrency
Channel: Tech Educators
Date: 2021-05-02

In this video you will learn, what is concurrency? and What are the problems occurred due to concurrency?

Concurrency Control is the management procedure that is required for controlling concurrent execution of the operations that take place on a database.

Concurrent Execution in DBMS
A. In a multi-user system, multiple users can access and use the same database at one time, which is known as the concurrent execution of the database. It means that the same database is executed simultaneously on a multi-user system by different users.
B. While working on the database transactions, there occurs the requirement of using the database by multiple users for performing different operations, and in that case, concurrent execution of the database is performed.
C. The thing is that the simultaneous execution that is performed should be done in an interleaved manner, and no operation should affect the other executing operations, thus maintaining the consistency of the database. Thus, on making the concurrent execution of the transaction operations, there occur several challenging problems that need to be solved.

Problems Due to Concurrency:
Problem 1: Lost Update Problems (W - W Conflict)
Problem 2: Dirty Read Problems (W-R Conflict)
Problem 3: Unrepeatable Read Problem (W-R Conflict)

Source: https://www.javatpoint.com/dbms-concurrency-control