HIVE over() 超全讲解

over()

over() 函数在Hive中运用广泛，通常搭配row_number() ,min(),max(),sum()来使用,总结下over函数划定窗口的范围

id	name	num
1	a	1
2	b	3
3	a	5
4	c	9
5	b	3

• over() 此时每一行的窗口都是所有的行

SELECT id,name,num,
sum(num) over() sum1 from aa

• over(order by id) id=1的窗口只有一行，id=2的窗口包括id=1,id=2

SELECT id,name,num,
sum(num) over(order by id) sum1 from aa

• over(partition by name) 每一行根据 name来区分窗口

SELECT id,name,num,
sum(num) over(partition by name) sum1 from aa

• over(partition by name order by id) 每一行根据 name来区分窗口,再根据order by 取具体的范围

SELECT id,name,num,
sum(num) over(partition by name order by id) sum1 from aa

• over( order by id range between 1 preceding and 1 following ) range 代表范围 preceding 向前 following 向后 窗口范围当前行前后一行

SELECT id,name,num,
sum(num) over( order by id range between 1 preceding and 1 following ) sum1 from aa

• over( order by id range between CURRENT ROW AND 1 following ) 窗口范围当前行和后面一行

SELECT id,name,num,
sum(num) over( order by id range between CURRENT ROW AND  1 following ) sum1 from aa