Bitkernel · CS Fundamentals

Classify concurrency anomaly between two transactions

TrueInterview

October 7, 2026 · 1 min read

Transactions T1 and T2 run at the same time and both access the shared data item A. Their operations take place in the following time order:

T1 reads A = 100.
T2 reads A = 100.
T1 writes A = A + 10 (so the value it would store is 110).
T2 writes A = A - 10 (using the value 100 it read earlier, so it stores 90). Which option best describes the concurrency problem in this scenario? Options:

A. The operation cannot be read repeatably (non-repeatable read).
B. The operation has no problems.
C. The operation reads dirty data.
D. The operation loses modifications (lost update). Overview: This question tests knowledge of database concurrency control and transaction isolation within the Software Engineering Fundamentals domain, specifically the ability to identify concurrency anomalies that affect data integrity and update correctness.

Bitkernel · CS Fundamentals

TrueInterview

October 7, 2026 · 1 min read

Transactions T1 and T2 run at the same time and both access the shared data item A. Their operations take place in the following time order:

T1 reads A = 100.
T2 reads A = 100.
T1 writes A = A + 10 (so the value it would store is 110).
T2 writes A = A - 10 (using the value 100 it read earlier, so it stores 90). Which option best describes the concurrency problem in this scenario? Options:

A. The operation cannot be read repeatably (non-repeatable read).
B. The operation has no problems.
C. The operation reads dirty data.
D. The operation loses modifications (lost update). Overview: This question tests knowledge of database concurrency control and transaction isolation within the Software Engineering Fundamentals domain, specifically the ability to identify concurrency anomalies that affect data integrity and update correctness.