Hive 分组取TOP N

id	num
1	50.31
3	26.31
3	71.11
4	26.07
1	11.08
1	72.58
4	48.63
1	46.63
2	67.54
2	94.24
2	5.28
1	80.11
4	14.32
4	78.11
4	52.50
4	86.34
1	97.27
1	97.59
1	59.92
1	40.91
2	66.10
2	25.36
3	26.87
1	50.76

表的结构如上表，查询每个id的前3num。

select id,num from

(select id,num,row_number() over(partition by id order by num desc) as row_num from {table}) a

where row_num <= 3;