sql技巧-滚动窗口分组

本文基于hive1.1.0-cdh5.12.1

将数据按N个一组进行分组

示例数据：

id
0
1
2
3
4
6
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要求：将id按一个长度为N的滚动窗口分组（N>1），并求出窗口区间(前闭后开)

参考结果：N=3

id	分组	窗口区间
0	1	[0-3)
1	1	[0-3)
2	1	[0-3)
3	2	[3-6)
4	2	[3-6)
5	2	[3-6)
6	3	[6-9)
7	3	[6-9)

参考实现：

set hivevar:win_size=3; --窗口大小
with t as  
(
select  i as id
from (select  7 as days ) t 
LATERAL VIEW 
posexplode(split(repeat(',',days),',')) pe as i, x 
) --构造一个测试表
------------------------SQL-------------------------------
select id
,floor(id/win_size)                 as group_id --除以窗口大小后向下取整，得到分组id
,floor(id/win_size)*win_size        as win_start--【分组id】*【窗口大小】=【窗口起始】
,(floor(id/win_size)+1)*win_size    as win_end  --【窗口起始】+【窗口大小】=(【分组id】+1)*【窗口大小】=【窗口终止(不含)】
,printf('[%d-%d)',floor(id/win_size)*win_size,(floor(id/win_size)+1)*win_size ) as window --使用printf格式窗口区间
from 
(select id,${hivevar:win_size} as win_size from t) t1;

+-----+-----------+------------+----------+----------+--+
| id  | group_id  | win_start  | win_end  | window   |
+-----+-----------+------------+----------+----------+--+
| 0   | 0         | 0          | 3        | [0-3)    |
| 1   | 0         | 0          | 3        | [0-3)    |
| 2   | 0         | 0          | 3        | [0-3)    |
| 3   | 1         | 3          | 6        | [3-6)    |
| 4   | 1         | 3          | 6        | [3-6)    |
| 5   | 1         | 3          | 6        | [3-6)    |
| 6   | 2         | 6          | 9        | [6-9)    |
| 7   | 2         | 6          | 9        | [6-9)    |
+-----+-----------+------------+----------+----------+--+