(Ienjed) au the Initial 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. Show the complete log just before the crash. T1 T2 T3 T4 T5 1. R(A) 2. R(D) 3. R(B) 4. R(E) 5. B = B -A 6. W(B) 7. R(C) 8. commit 9. R(B) 10. R(A) 11. B = B+E 12. R(A) 13. W(B) 14. D = D+A 15. commit 16. W(D) 17. R(B) 18. R(E) 19. B = B+A 20. W(B) 21. C= C+20 22. E = E-20 W(C) 23. 24. commit 25. W(E)

Computer Networking: A Top-Down Approach (7th Edition)
7th Edition
ISBN:9780133594140
Author:James Kurose, Keith Ross
Publisher:James Kurose, Keith Ross
Chapter1: Computer Networks And The Internet
Section: Chapter Questions
Problem R1RQ: What is the difference between a host and an end system? List several different types of end...
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Question
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. Show the complete log just before the crash.
T1
T2
T3
T4
T5
1.
R(A)
2.
R(D)
3.
R(B)
4.
R(E)
5.
B = B - A
6.
W(B)
7.
R(C)
8.
commit
9.
R(B)
10.
R(A)
11.
B = B+E
12.
R(A)
13.
W(B)
14.
D = D+A
15.
commit
16.
W(D)
17.
R(B)
18.
R(E)
19.
B = B+A
20.
W(B)
C= C+20
E = E-20
W(C)
21.
22.
23.
24.
commit
25.
W(E)
Transcribed Image Text: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. Show the complete log just before the crash. T1 T2 T3 T4 T5 1. R(A) 2. R(D) 3. R(B) 4. R(E) 5. B = B - A 6. W(B) 7. R(C) 8. commit 9. R(B) 10. R(A) 11. B = B+E 12. R(A) 13. W(B) 14. D = D+A 15. commit 16. W(D) 17. R(B) 18. R(E) 19. B = B+A 20. W(B) C= C+20 E = E-20 W(C) 21. 22. 23. 24. commit 25. W(E)
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