sql - Hive collect_set() 但要删除连续的重复项

Question

我想在使用 hive 时删除数组中的连续重复项。
collect_list()保留所有重复项，而 collect_set()只保留不同的条目。我有点需要一些中间立场。

例如，从下表:

id  |  number
==============
fk        4
fk        4
fk        2
4f        1
4f        8
4f        8
h9        7
h9        4
h9        7

我想得到这样的东西:

id | aggregate
===========================
fk   Array<int>(4,2)
4f   Array<int>(1,8)
h9   Array<int>(7,4,7)

Answer 1

使用 lag()解析函数获取前一个数字并与当前数字进行比较以检查连续数字。

演示:

with your_table as (--replace this subquery with your table
select stack(11, --the number of tuples
'fk',4,'2019-01-01 10:10:10.123',
'fk',4,'2019-01-01 10:10:10.124',
'fk',2,'2019-01-01 10:10:10.125',
'4f',1,'2019-01-01 10:10:10.126',
'4f',8,'2019-01-01 10:10:10.127',
'4f',8,'2019-01-01 10:10:10.128',
'h9',7,'2019-01-01 10:10:10.129',
'h9',4,'2019-01-01 10:10:10.130',
'h9',7,'2019-01-01 10:10:10.131',
'h9',7,'2019-01-01 10:10:10.132',
'h9',7,'2019-01-01 10:10:10.133'
) as (id, number, order_ts)
) --replace this subquery with your table

select id, collect_list(case when number = lag_number then null else number end) as aggregate
  from 
      (select id, number, order_ts,
              lag(number) over (partition by id order by order_ts) lag_number
         from your_table 
       distribute by id sort by order_ts
      )s         
  group by id;

结果:

id  aggregate   
4f  [1,8]   
fk  [4,2]   
h9  [7,4,7]