使用配置单元功能对数据进行排序

Question

我有一个蜂巢表

create table abc ( id int, channel string, time int ); 

insert into table abc values
(1,'a', 12),
(1,'c', 10),
(1,'b', 15),
(2,'a', 15),
(2,'c', 12),
(2,'c', 7);

我希望结果表看起来像这样-

id , journey
1, c->a->b
2, c->c->a

journey列按id

按时间升序排列

我尝试过

select id , concat_ws(">", collect_list(channel)) as journey
from abc 
group by id

但它不保留顺序。

Answer 1

使用子查询和按时间排序（以保留顺序），然​​后在外部查询中使用带有group by子句的collect_list。

hive> select id , concat_ws("->", collect_list(channel)) as journey from 
      ( 
        select * from abc order by time
       )t 
        group by id;
    +-----+----------------+--+
    | id  |    journey     |
    +-----+----------------+--+
    | 1   | 'c'->'a'->'b'  |
    | 2   | 'c'->'c'->'a'  |
    +-----+----------------+--+