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(Solved) : Consider Following Four Transactions Transaction T1 Readitem Readitem D Writeitem D Transa Q27986249 . . .

Consider the following four transactions:

*Transaction T1: read_item(A); read_item(D); write_item(D);

*Transaction T2: read_item(B); write_item(B); read_item(D);write_item(D);

*Transaction T3: read_item(C); write_item(C);

*Transaction T4: read_item(D); write_item(D); read_item(A);write_item(A);

Following is a log corresponding to a particularschedule at the point of a system crash.

[start_transaction, T1]

[read_item, T1, A]

[read_item, T1, D]

[write_item, T1, D, 20, 25]

[commit, T1]

[checkpoint]

[start_transaction,T2]   

[read_item, T2, B]

[write_item, T2, B, 12, 18]

[start_transaction, T4]

[read_item, T4, D]

[write_item, T4, D, 15, 25]

[start_transaction, T3]

[write_item, T3, C, 30, 40]

[read_item, T4, A]

[write_item, T4, A, 30, 20]

[commit, T4]

[read_item, T2, D]

[write_item, T2, D, 15, 25]<-System Crash

Suppose that we use theimmediate update protocol with checkpointing. Specify thefollowing:

a. Which transaction will not be involved in the recoveryprocess and why?

b. Which transactions are rolled back?

c. Which operations in the log are redoneand why?

d. Which operations in the log are undone? List theoperations in the correct order that were undone.

Expert Answer

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Answer to Consider Following Four Transactions Transaction T1 Readitem Readitem D Writeitem D Transa Q27986249 . . .