Consider concurrent execution of two transactions π1 and π2 in a DBMS, bothβ¦
Consider concurrent execution of two transactions π1 and π2 in a DBMS, both of which access a data object π΄. For these two transactions to not conflict on π΄, which one of the following statements must be true?
Answer: A. (A) Both π1 and π2 only read π΄ β Two operations conflict if: They belong to different transactions. They access the same data item. At least one of them is a write operation. Therefore, theβ¦
- A.
(A) Both π1 and π2 only read π΄
- B.
(B) π1 reads π΄ and π2 writes π΄
- C.
(C) π1 writes π΄ and π2 reads π΄
- D.
(D) Both π1 and π2 write π΄
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Correct answer: A
Two operations conflict if:
They belong to different transactions.
They access the same data item.
At least one of them is a write operation.
Therefore, the only case where there is no conflict is when both operations are reads.