What behavior does each level of transaction isolation provide?
sobes.tech AI
Answer from AI
Transaction isolation levels determine how and when the changes made by one transaction become visible to other transactions, and prevent various anomalies:
-
READ UNCOMMITTED — the lowest isolation level. Transactions can see uncommitted changes of other transactions (dirty read). All anomalies are possible.
-
READ COMMITTED — a transaction sees only committed changes. It prevents dirty reads but allows non-repeatable reads and phantom reads.
-
REPEATABLE READ — guarantees that data read in a transaction will not change until it completes. It prevents dirty and non-repeatable reads, but phantom reads can occur.
-
SERIALIZABLE — the strictest level. Transactions are executed sequentially, fully preventing all anomalies, but reducing concurrency and performance.
The choice of level depends on the data integrity requirements and application performance.