3. Recovery: (6 marks) Use the sample schedule and system log shown in Figure 6.3 to answer Question 3.1. Consider a database with the data items (A, B, C, D) and the operations associated with five transactions. We consider the log shown on Figure 6.3a to recover from this system failure. Note that log record (write_item, T, X, old, new] indicates that transaction T, changes the value of X from old to new. (start_transaction, 72) (write_item, T2, A, 10, 11) (start_transaction, 71) (commit, T2) (checkpoint) (start_transaction, 73] (write_item, T3, B, 20, 21) (start_transaction, 74) (write_item, T4, C, 30, 31) (commit, 74) (write_item, 13, D, 40, 41] (write_item, TI, C, 31, 32] (start_transaction,75) (write_item, 75, D, 41, 42] [commit, T3) (commit, T5) System failure Figure 6.3a: Sample Schedule and System Log for Question 3.1 Question 3.1 (3 marks) Assume that the system uses the deferred update protocol with checkpointing (see Slide 7 on Lecture 20), describe the recovery process from the system crash. Specify which transactions are rolled back, which operations in the log are redone and which (if any) are undone