What types of anomalies that occur during transaction processing are impossible to encounter in a system that uses an isolation mechanism?

Transaction management systems have various types of anomalies that can occur during concurrent transaction execution:

• Dirty Read — reading data that has been modified but not yet committed by another transaction.
• Non-repeatable Read — reading the same data multiple times within a transaction yields different results due to modifications by other transactions.
• Phantom Read — new rows appear when re-executing a query, added by other transactions.

The transaction isolation mechanism aims to prevent these anomalies. Depending on the isolation level (e.g., Serializable, Repeatable Read), some or all of these anomalies can be completely eliminated.

For example, at the Serializable isolation level, dirty reads, non-repeatable reads, and phantom reads are impossible because transactions are executed as if they were sequential.

Thus, in a system with a properly configured transaction isolation mechanism, anomalies related to inconsistent data reading, such as dirty reads, non-repeatable reads, and phantom reads, cannot occur.