問題文
A session updates two hundred rows and has not issued a COMMIT yet. A second session queries the same table at that moment. What does the second session see and what happens if the first session then issues a ROLLBACK?
選択肢
- The second session reads a mixture of old and new values and the rollback leaves the newer rows in the table as they are.
- The second session reads the values from after the update and the rollback leaves the rows in the state the query already showed.
- The second session reads the values from before the update and the rollback returns the rows to the state the query already showed.
- The second session waits until the first one finishes and the rollback releases the reader with the older values in place.