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Consider two transactions T1 and T2, and four schedules S1 , S2 , S3 , S4 of T1 and T2 as given below :
T1 : R1 [X] W1 [X] W1 [y]
T2 : R2 [x] R2 [y] W2 [y]
S1 : R1 [x] R2 [x] W1 [x] W1 [y] W2 [y]
S2 : R1 [x] R2 [x] R2 [y] W1 [x] W2 [y] W1 [y]
S3 : R1 [x] W1 [x] R2 [x] W1 [y] R2 [y] W2 [y]
S4 : R2 [x] R2 [y] R1 [x] W1 [x] W1 [y] W2 [y]
Which of the above schedules are conflict-serializable ?
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- S1 and S2
- S2 and S3
- S3 only
- S4 only
- S1 and S2
Correct Option: B
Let us construct the schedule and transition diagram to determine the conflict :
Schedule S2
Schedule S3
Here, we can see that S1 and S4 are not conflict serializable but S2 and S3 are conflict serializable.
