Consider the following (partial) schedule in a centralized database system Assume the initial values of data items A, B, C, D, and E are 10, 20, 30, 40, and 50, respectively. Assume logging is used for recovery For simplicity, we assume each write is immediately written to the database (on disk) (and hence, the corresponding log record must be written to the stable storage before the database block on disk is written) Assume the system has crashed right after step 25 T2 R(A R(B) T1 T3 R D) R(E R(C) commit R(B) 10 RA 12 13.W (B) 14 D+A commit W (D) 16 17 18 19 20 R(E C=C+20 W(C) 23 24 commit W(E) (a) Show the complete log just before the crash. b) Which portion of the log is in stable storage when the system crashes? Why? Consider the following (partial) schedule in a centralized database system Assume the initial values of data items A, B, C, D, and E are 10, 20, 30, 40, and 50, respectively. Assume logging is used for recovery For simplicity, we assume each write is immediately written to the database (on disk) (and hence, the corresponding log record must be written to the stable storage before the database block on disk is written) Assume the system has crashed right after step 25 T2 R(A R(B) T1 T3 R D) R(E R(C) commit R(B) 10 RA 12 13.W (B) 14 D+A commit W (D) 16 17 18 19 20 R(E C=C+20 W(C) 23 24 commit W(E) (a) Show the complete log just before the crash. b) Which portion of the log is in stable storage when the system crashes? Why