Concurrency Control and Recovery
Concurrent execution of user programs is essential for good DBMS performance.
- Because disk accesses are frequent, and relatively slow, it is important to keep the cpu humming by working on several user programs concurrently.
Interleaving actions of different user programs can lead to inconsistency: e.g., check is cleared while account balance is being computed.
DBMS ensures such problems don’t arise: users can pretend they are using a single-user system.