시나리오 시간 Transaction 1 Transaction 2 Transaction 3 비고 09:00 SELECT last_name, salary FROM employees WHERE employee_id=200; HARD PARSING (DISK IO) 09:01 UPDATE employees SET salary = 8000 WHERE employee_id=200; LOCK(TM/TX) 걸림 09:02 SELECT last_name, salary FROM employees WHERE employee_id=200; SOFT PARSING (MEM IO) UNDO 데이터에서 가져옴 09:03 UPDATE employees SET salary = 8000 WHERE employee_id=200; LOCK..
