An audit of a banking transactions system has found that on an earlier…
2025
An audit of a banking transactions system has found that on an earlier occasion, two joint holders of account 𝐴 attempted simultaneous transfers of Rs. 10000 each from account 𝐴 to account 𝐵. Both transactions read the same value, Rs. 11000, as the initial balance in 𝐴 and were allowed to go through. 𝐵 was credited Rs. 10000 twice. 𝐴 was debited only once and ended up with a balance of Rs. 1000.
Which of the following properties is/are certain to have been violated by the system?
- A.
Atomicity
- B.
Consistency
- C.
Isolation
- D.
Durability
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Correct answer: B, C
The system has certainly violated Isolation and Consistency.
Isolation: Both transactions read the same initial balance (₹11000) and executed concurrently, causing a lost update.
Consistency: The account invariant was violated (₹20000 credited to B, but A debited only once).
Durability is not involved here.
Atomicity is not certain to be violated because each transaction may still have completed fully on its own.
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