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For questions 1 to 5: For the given schedules, determine if each is: a) Conflict serializable b) Recoverable c) Avoid Cascading Aborts d) Strict Question-1: Sa: r1(x); r2(x); w2(x); w1(x); a2; c1. Question-2: Sb: r1(x); r2(x); w2(x); w1(x); c2; c1. Question-3: Sc: r1(x); w1(x); r2(x); w1(x); c2; c1. Question-4: Sd: r1(x); w1(x); r2(x); w1(x); a2; c1. Question-5: Se: r1(x); r2(x); w2(x); c2; w1(x); c1; r3(x); c3. Question-6: If there is any, identify any equivalence to concurrent schedule Sf ? Sf: r1(x); w1(x); r3(x); r3(z); r2(y); r3(y); w3(y); c3; c2; c1. Question-7: What serial schedule is the schedule equivalent to – or not? Note: there is only one schedule (Sg) – the notation spans two lines of text Sg: r1(x); w1(x); r1(y); w1(y); r2(x); r2(y); w2(y); r2(z); r1(z); w1(z); c1; r3(y); c2; r3(z); w3(z); r4(z); c3; a4. Question-8: To make the schedule strict, which operation should be moved, and where to? Sh: r1(X); r2(B); r2(X); r1(Z); r2(A); r3(Y); w1(X); c1; w2(A); w3(Y); w2(B); c3; c2; Comp207 2016-17 Assignment-1: Page 4 Question-9: Using recovery with UNDO/REDO immediate update, what will be the BFIM values of objects J, K and L immediately after recovery is completed after time t=10 but before reexecution of the schedule commences before time t=11? BFIM: item-J = 750; item-K = 550; item-L = 430 time = 9: Database fails time = 10: UNDO/REDO recovery algorithm initiated time = 11: Recovery complete – schedule is allowed to re-start time Operation Object BFIM AFIM 0 checkpoint checkpoint checkpoint checkpoint 1 start T1 2 write_item T1,J,1250 750 3 start T2 4 write_item T2,K,400 550 5 commit T2 6 start T3 7 write_item T3,L,250 430 8 abort T1 9 FAILURE Database 10 UNDO/REDO Schedule 11 Restart Schedule Question-10: For a concert venue, with two theatres in the venue, capacity of 305 seats each theatre. There are two bands (Band-A and Band-B) booked to play at the same time on the same night – one in each theatre in the venue. Band-A currently has 301 seats reserved for the night Band-B currently has 300 seats reserved for the night A customer changes their reservation for 4 seats from Band-A to Band-B Another customer wants to reserve 8 seats for Band-A The transactions execute as concurrent schedule Si Si: r1(A); r1(B); A=A-4; B = B+4; r2(A); A=A+8; w1(A); w1(B); w2(A); c2; c1. After execution, what are the values for A and B? What should they be?