Which of the DBMS component ensures that concurrent execution of multiple…

Correct answer: Transaction processing system

Explanation:

• Role: The transaction processing system (transaction manager) enforces concurrency control and the ACID properties so that concurrently running transactions leave the database in a consistent state.

• ACID properties: atomicity, consistency, isolation, durability — these properties collectively ensure correctness of transactions and consistency of the database.

• Common concurrency-control mechanisms: locking (shared/exclusive locks), timestamp ordering, optimistic concurrency control, and multiversion concurrency control (MVCC). These mechanisms prevent conflicting interleavings and preserve isolation.

• Why other components are not correct:

  • Logs: Support recovery (undo/redo) and durability but do not coordinate concurrent transactions during normal execution.

  • Buffer manager: Manages in-memory caching of disk pages to improve I/O performance; it does not ensure transaction isolation or concurrency control.

  • File manager: Handles physical storage and disk structures; it is not responsible for enforcing ACID or concurrency control.