Write SECTION B: Question B3, your name and student ID on the top of the first page of your answer to this question. QUESTION B3. (8 marks) (a) (4 marks) You are given the concurrent schedule S below involving two transactions. Using read/write operations together with their time-stamps as examples, briefly explain why Dirty Read, Unrepeatable Read and Lost Update can be problematic in the context of transaction processing. 9 (b) (4 marks) Suppose that the log file below survived a crash under the log-based recovery scheme with checkpointing: (i) (2 marks) With immediate database modification strategy, which transactions should be redone and which transactions should be undone? What are the final values of X,Y and Z after recovery? (ii) (2 marks) Discuss what deferred database modification strategy is, and if it is consistent with the log record provided above. Assume that the original values of each item X, Y and Z were 100 before transaction T0 started. Modify the provided log file in light of this information in order to get the desired log file for deferred database modification strategy. Which transactions should be redone and which transactions should be undone now? What are the final values of X, Y and Z after recovery