Which pair of operations from two different transactions T1 and T2 does NOT conflict?
Correct answer B. R1(X) and R2(X)
Explanation
Two operations conflict when they belong to different transactions, access the same data item, and at least one of them is a write. Two reads of X do not change it, so their order makes no difference and they can be swapped freely. Read-write, write-read and write-write pairs on the same item conflict, because swapping them can change what a transaction reads or the final value.
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