Which of the following concurrency control mechanisms is most effective in preventing 'dirty reads' by ensuring that a transaction reads only committed data?
Question 2
Consider a database system that uses a 'write-ahead logging' (WAL) protocol for recovery. If a transaction commits, but the database crashes before the actual data pages are written to disk, how does WAL ensure durability?
Question 3
Which of the following scenarios best exemplifies a 'cascading rollback' in a database system?
Question 4
In the context of database concurrency control, what is the primary challenge that 'optimistic concurrency control' (OCC) aims to address, compared to pessimistic approaches like Two-Phase Locking (2PL)?
Question 5
Which ACID property is most directly violated if a database system allows a transaction to read data that has been modified by another transaction but not yet committed, and the modifying transaction subsequently aborts?
