Consider the following snapshot of the transaction log in Table 1 while three transactions T1, T2...

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Consider the following snapshot of the transaction log in Table 1 while three transactions T1, T2 and T3 are executing: T1: Changing the employee who manages a profile. T2: Updating the password of member Penny@hotmail.com. T3: Updating the rating of App 345. Table 1: Transaction Log Snapshot LogId TransId Operation Table T1 Start 101 T2 Start 102 103 T2 104 T1 105 T2 106 107 T3 108 T3 109 T3 Update Member Profile Update Commit CHKPT T1 WH Start Update Commit RowId Penny@hotmail.com Password 28000 ColumnName Before After Application 345 myPWD Employeeld E55 E89 4#6B Rating 3 4 (a) Using the log information, write SQL statements corresponding to the three transactions. [9 marks] (b) Suppose that after logId 109, a system failure occurred. Explain in detail how the system will recover from this system failure. Your explanation should include the actions which will be performed for transactions T1, T2 and T3 when the system restarts and state why these actions are necessary. [15 marks] Consider the following snapshot of the transaction log in Table 1 while three transactions T1, T2 and T3 are executing: T1: Changing the employee who manages a profile. T2: Updating the password of member Penny@hotmail.com. T3: Updating the rating of App 345. Table 1: Transaction Log Snapshot LogId TransId Operation Table T1 Start 101 T2 Start 102 103 T2 104 T1 105 T2 106 107 T3 108 T3 109 T3 Update Member Profile Update Commit CHKPT T1 WH Start Update Commit RowId Penny@hotmail.com Password 28000 ColumnName Before After Application 345 myPWD Employeeld E55 E89 4#6B Rating 3 4 (a) Using the log information, write SQL statements corresponding to the three transactions. [9 marks] (b) Suppose that after logId 109, a system failure occurred. Explain in detail how the system will recover from this system failure. Your explanation should include the actions which will be performed for transactions T1, T2 and T3 when the system restarts and state why these actions are necessary. [15 marks]

Answer rating: 100% (QA)

a answer SQL statement for T1 UPDATE Profile SET EmployeeId E89 WHERE ... View the full answer