select /*+index(table_a columna)*/ distinct tx_oper_id
from table_a
where not exists(
select *
from
table_b
where b.id=a.id
)

参考Oracle官方说明

https://docs.oracle.com/cd/B19306_01/server.102/b14200/conditions012.htm

EXISTS Condition

An EXISTS condition tests for existence of rows in a subquery.

Table 7-11 shows the EXISTS condition.

Table 7-11 EXISTS Condition

EXISTS

SELECT department_id
  FROM departments d
  WHERE EXISTS
  (SELECT * FROM employees e
    WHERE d.department_id 
    = e.department_id);