hive取随机的数据,可以使用rand()函数,用rand()对数据排序,取topN
如果要用到分组取随机数,比如每个班级随机取10人,针对这种每个分组取topN的情况,可以使用
row_number() over(partition by fieldx order by rand()) as rn
select id,
class_id
from(
select id,
class_id,
row_number() over(partition by class_id order by rand()) as rn
from table ) tb
where tb.rn <= 10