What concurrent processing problem occurs when a transaction rereads data and finds new rows that were inserted by a different transaction since the prior read?
A) Nonrepeatable reads
B) Phantom reads
C) Dirty reads
D) Serialized reads
E) Unlocked reads

Question

Quizplus · Accepted Answer

This is a classic example of a phantom read, where a transaction rereads data and finds new rows that were inserted by a different transaction since the prior read. Phantom reads occur when a transaction reads the same rows twice but obtains different results because another transaction has inserted new rows in the interval. Nonrepeatable reads occur when a transaction rereads the same data and finds different data due to changes made by another transaction. Dirty reads occur when a transaction reads data that has been updated by a different transaction but not yet committed. Serialized reads and unlocked reads are not relevant to this scenario.

What Concurrent Processing Problem Occurs When a Transaction Rereads Data