Append logs in recovery. Justify the answer.

Start T1

Read T1, A

Read T1, D

Write T1, D, 20, 25

Commit T1

Checkpoint

Start T2

Read T2, B

Write T2, B, 12, 18

Start, T4

Read T4, D

Write T4, D, 25, 15

Start T3

Write T3, C, 30, 40

Read T4, A

Write T4, A, 30, 20

Commit T4

Read T2, D

Write T2, D, 15, 25

System crash -----

Databases Systems (Recovery System) 1. Consider the following sequence of 'logs' from transactions T1, T2, T3 and T4. Represent transactions on the timeline as follows: Checkpoint FAILURE D E Use the following table : Log Redo Phase Undo Phase