如何解决通过滚动窗口分区计算不同的客户
我的问题类似于redshift: count distinct customers over window partition,但我有一个滚动窗口分区。
我的查询看起来像这样,但不支持Redshift中的COUNT个
select p_date,seconds_read,count(distinct customer_id) over (order by p_date rows between unbounded preceding and current row) as total_cumulative_customer
from table_x
我的目标是计算每个日期之前的唯一身份客户总数(因此滚动窗口)。
我尝试使用dense_rank() approach,但由于我无法使用这样的窗口函数,它只会失败
select p_date,max(total_cumulative_customer) over ()
(select p_date,dense_rank() over (order by customer_id rows between unbounded preceding and current row) as total_cumulative_customer -- WILL FAIL HERE
from table_x
任何解决方法或其他方法都将有所帮助!
编辑:
输入数据样本
+------+----------+--------------+
| Cust | p_date | seconds_read |
+------+----------+--------------+
| 1 | 1-Jan-20 | 10 |
| 2 | 1-Jan-20 | 20 |
| 4 | 1-Jan-20 | 30 |
| 5 | 1-Jan-20 | 40 |
| 6 | 5-Jan-20 | 50 |
| 3 | 5-Jan-20 | 60 |
| 2 | 5-Jan-20 | 70 |
| 1 | 5-Jan-20 | 80 |
| 1 | 5-Jan-20 | 90 |
| 1 | 7-Jan-20 | 100 |
| 3 | 7-Jan-20 | 110 |
| 4 | 7-Jan-20 | 120 |
| 7 | 7-Jan-20 | 130 |
+------+----------+--------------+
预期产量
+----------+--------------------------+------------------+--------------------------------------------+
| p_date | total_distinct_cum_cust | sum_seconds_read | Comment |
+----------+--------------------------+------------------+--------------------------------------------+
| 1-Jan-20 | 4 | 100 | total distinct cust = 4 i.e. 1,2,4,5 |
| 5-Jan-20 | 6 | 450 | total distinct cust = 6 i.e. 1,3,5,6 |
| 7-Jan-20 | 7 | 910 | total distinct cust = 6 i.e. 1,6,7 |
+----------+--------------------------+------------------+--------------------------------------------+
解决方法
此操作:
select p_date,seconds_read,count(distinct customer_id) over (order by p_date rows between unbounded preceding and current row) as total_cumulative_customer
from table_x;
您可以通过两个聚合级别来完成几乎所有您想做的事情:
select min_p_date,sum(count(*)) over (order by min_p_date rows between unbounded preceding and current row) as running_distinct_customers
from (select customer_id,min(p_date) as min_p_date
from table_x
group by customer_id
) c
group by min_p_date;
总结读取的秒数也有些棘手,但是您可以使用相同的想法:
select p_date,sum(sum(seconds_read)) over (order by p_date rows between unbounded preceding and current row) as seconds_read,sum(sum(case when seqnum = 1 then 1 else 0 end)) over (order by p_date rows between unbounded preceding and current row) as running_distinct_customers
from (select customer_id,p_date,row_number() over (partition by customer_id order by p_date) as seqnum
from table_x
) c
group by min_p_date;
,
一种解决方法是使用子查询:
select p_date,(
select count(distinct t1.customer_id)
from table_x t1
where t1.p_date <= t.p_date
) as total_cumulative_customer
from table_x t
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