6. What is a scheduler, what does it do, and why is its activity important to concurrency control?
The scheduler is the DBMS component that establishes the order in which concurrent database operations are executed. The scheduler interleaves the execution of the database operations (belonging to several concurrent transactions) to ensure the serializability of transactions. In other words, the scheduler guarantees that the execution of concurrent transactions will yield the same result as though the transactions were executed one after another. The scheduler is important because it is the DBMS component that will ensure transaction serializability. In other words, the scheduler allows the concurrent execution of transactions, giving end users the impression that they are the DBMS's only users.