Impala - 在多个日期上运行相同的查询

Posted 2023-03-22

【中文标题】Impala - 在多个日期上运行相同的查询

【英文标题】：Impala - Running Same Query Over Multiple Dates

【发布时间】：2020-03-20 22:27:45

【问题描述】：

我有下面的 Impala 查询，它设置为计算数据集中某一天而不是前一天的设备数量。我想在多个日期（过去一年中的每一天）运行此查询。

在 Impala 中有没有办法做到这一点？我知道没有循环功能，但不确定是否有某种方法可以将日期数组传递给变量，以便查询在连续日期上运行。谢谢！

SELECT COUNT(DISTINCT devices) 
FROM request
WHERE devices NOT IN (
    SELECT devices
    FROM request
    WHERE forwarded_dt =  CAST((CAST('2020-03-17' as timestamp)) as BIGINT)*1000
    )  
AND forwarded_dt =  CAST((CAST('2020-03-18' as timestamp)) as BIGINT)*1000;

【参考方案1】：

您可以使用lag()。我认为：

select day,
       count(*) as num_devices_on_day,
       sum(case when prev_day = day - interval '1' day then 0 else 1 end) as new_devices_on_day
from (select device, date_trunc('day', timestamp) as day,
             lag(date_trunc('day', timestamp)) over (order by min(timestamp)) as prev_day
      from requests
     ) r
group by day;