Client server databases：練習問題

Which of the following describes the function of record locking in a client-server database system?

In the context of database management, what is serialisation used to ensure?

A database uses record locking to manage concurrency. If Transaction A holds a lock on Record 1 and requests a lock on Record 2, while Transaction B holds a lock on Record 2 and requests a lock on Record 1, what situation has occurred?

In a client-server database, what is the primary risk associated with concurrent access where two different users attempt to modify the same record at the same time?

How does timestamp ordering manage concurrent access in a client-server database?

In a client-server database system, what is the specific role of record locking when multiple clients attempt to modify the same data item simultaneously?

Define the term serialisation in the context of concurrent access in a client-server database.

Describe the commitment ordering method for managing concurrent database access.

A client-server database system allows multiple users to access and update records simultaneously. This environment poses risks to data integrity if not managed correctly.

a. Define the "lost update" problem in the context of concurrent database access. (2 points)

b. Explain how record locking is used to prevent the lost update problem, and describe one potential drawback of using this method. (3 points)

A bank uses a client-server database to manage accounts. When a customer withdraws money, the system must ensure the transaction is Atomic.

a. Define what is meant by 'Atomicity' in the context of database transactions. (2 points)

b. Describe a scenario in this banking system where a lack of atomicity could lead to data inconsistency. (2 points)

c. Explain how Commitment Ordering can be used to manage concurrent transactions. (2 points)