Following is the schedule A for transactions T1, T2, and T3: Note: We assume a t
ID: 3721084 • Letter: F
Question
Following is the schedule A for transactions T1, T2, and T3:
Note: We assume a transaction will be committed immediately after all the read/write operations of it are done.
Schedule A Time ransaction T2 T3 write read(X) read(Z) write 4 read(z) read(Z) read wrt read(X) 10 read(Y) u) Assume that the sstem crashes at time 8, what should be done to recover the system? (3 marks) 2) Assume a checkpoint is made at time 7, what should be done to the three transactions when the crash happens at time 8? (3 marks)Explanation / Answer
1) we need to use check points so that all the previous logs are removed from the system and stored permanently in a storage disk The recovery system reads the logs backward from the end to last checkpoint.
2)since there are no commited transactions till time 7 and when a check point is placed at time 7 all the transactions are made in undo list so that even when the crash happens at time 8 all the transactions in the undo list are stored and once after recovery the transaction continues to run after recovery