partition by 범위 default 전략

[white-gyu]

문제

• 왜 partition 범위 지정을 하지 않으면 이상한 값이 나올까?
• 아래 쿼리 결과 동작 원리 알아오기

query	결과
select DEPTNO, ename, SAL, last_value(ename) over ( partition by deptno order by sal desc ) from emp;
select DEPTNO, ename, SAL, last_value(ename) over ( partition by deptno order by sal desc rows between current row and unbounded following ) from emp;