Which of the following concurrency anomalies is also known as a read-write…

Correct answer: Unrepeatable read

• A read-write conflict occurs when one transaction reads a data item and another transaction later writes/updates the same item before the first transaction reads it again.

• This leads to an unrepeatable read: the same transaction may get different values for the same row in two reads.

• Conflicts are named by the order of the two operations on the same item: read then write (R-W) → unrepeatable read; write then read (W-R) → dirty read / uncommitted dependency; write then write (W-W) → lost update.

• Note: a dirty read does involve a read, but it is the second operation (it reads an earlier uncommitted write), so it is a write-read conflict, not a read-write conflict.