Question
Consider aserial schedule which involves 3 data items A, B, C with initial value 1000, 2000, 800, respectively. Assuming the sytem has crashed, for any
Consider aserial schedule <T 0 ,T 1 ,T 2 > which involves 3 data items A, B, C with initial value 1000, 2000, 800, respectively. Assuming the sytem has crashed, for any of the following log files, state the corresponding recovery plan (i.e list the transactions needed to be undone and redone in order and for each transacton T, state the values of the data items that are involved in the transaction T after the undone and redone operation)
a. <T 0 ,start>, <T 0 , A, 1000, 900>, <T 0 , B, 2000, 2100>
b. <T 0 , start>, < T 0 , A, 100, 900>, <T 0 , B, 2000, 2100>, <T 0, commit>, < T 1 , start>, <T 1 , C, 800, 900>
c. <T 0 , start>, <T 0 , A, 1000, 900>, < T 0, B, 2000, 2100>, <T 0 , commit>, <T 1 , start>, <T 1 , C, 800, 900>, <T 1, commit>, <T 2 , C, 900, 1000>
d. <T 0 , start>, <T 0 , A, 900>, <T 0 , B, 2100>
e. <T 0 , start>, < T 0 , A, 900>, <T 0 , B, 2100>, <T 0 , commit>, <T 1 , start>, <T 1 , C, 900>, <T 1 , commit>, <T 2 , C, 900,1000>
Step by Step Solution
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There are 3 Steps involved in it
Step: 1
a Since T0 has not committed yet and the system crashed So Undo T0 needs to be done since is present ...Get Instant Access to Expert-Tailored Solutions
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Step: 2
Step: 3
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