配置单元查询中的串联

问题描述

我有一个蜂巢表

col1   col2
1     ["apple","orange"]
1     ["orange","banana"]
1     ["mango"]
2     ["apple"]
2     ["apple","orange"]

有数据类型

col1 int
col2 array<string>

我想查询类似的内容：

select col1,concat(col2) from table group by col1;

输出应为：

1    ["apple","orange","banana","mango"]
2    ["apple","orange"]

蜂巢中有执行此操作的功能吗？

我也将此数据写入csv，当我将其作为数据帧读取时，我得到的col2 dtype为object。有没有办法将其输出为array。

解决方法

尝试展开数组，然后通过按collect_set分组使用 col1 函数。

Example:

Input:

select * from table;
OK
dd.col1 dd.col2
1       ["apple","orange"]
1       ["mango"]
1       ["orange","banana"]

---

select col1,collect_set(tt1)col2 from (
   select * from table lateral view explode(col2) tt as tt1
)cc 
group by col1;

Output:

col1    col2
1       ["apple","orange","mango","banana"]