Intermediate
Database Management Systems
Q71 / 100
What is a phantom read?
Correct! Well done.
Incorrect.
The correct answer is A) When a transaction re-runs a range query and finds new rows that another committed transaction inserted, which weren't present the first time
A
Correct Answer
When a transaction re-runs a range query and finds new rows that another committed transaction inserted, which weren't present the first time
Explanation
Phantom reads happen when a range query (e.g., WHERE age > 30) returns a different set of rows on re-execution because rows matching the predicate were inserted or deleted by other committed transactions. SERIALIZABLE isolation prevents this.
Progress
71/100