Table 5 shows the airlines transaction log file. Suppose that part of the airlines computer system fails
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Question:
- Table 5 shows the airline’s transaction log file. Suppose that part of the airline’s computer system fails at 15:06. Assume that the DBMS is using the Immediate Update protocol.
- Describe the actions that the recovery manager would take to recover from the failure. Explain why each action is taken.
- Describe how the recovery manager would use the recovery log during the recovery from the failure. State the order in which it would do things.
Transaction | Data items locked by transaction | Data items transaction is waiting to lock |
T1 | C | |
T2 | B, C | E |
T3 | A, E | |
T4 | D | A |
T5 | A, B, D |
Table 4: Information on locks.
Transaction ID | Time | Operation | Seat | Before Image | After Image |
T1 | 14:40 | Start | |||
T1 | 14:41 | Delete | S1 | Kahn | |
T2 | 14:43 | Start | |||
T2 | 14:44 | Delete | S16 | ||
T2 | 14:46 | Update | S3 | Smith | Patel |
T3 | 14:48 | Start | |||
T1 | 14:49 | Update | S5 | Jones | Wu |
T1 | 14:51 | Commit | |||
T2 | 14:52 | Insert | S9 | McKay | |
T3 | 14:55 | Delete | S18 | Dixon | |
T2 | 14:57 | Commit | |||
14:58 | Checkpoint | ||||
T4 | 14:59 | Start | |||
T3 | 15:01 | Commit | |||
T4 | 15:05 | Update | S9 | Green | Ali |
Table 5: Recovery Log File
Related Book For
Systems analysis and design
ISBN: 978-0136089162
8th Edition
Authors: kenneth e. kendall, julie e. kendall
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