关于hive开窗函数的问题

如果over() 则开窗的聚合函数统计的所有行

如果over(partition by xx order by xx) 时，开窗的聚合函数统计的是相同partition by 后的字段按照order by 后的字段排序后区内行首到当前行，及相当于默认over(partition by xx order by xx rows between UNBOUNDED PRECEDING and current row)