此查询每月失败一次，如何重构？答案

【问题标题】：This query fails once per month, how can it be refactored?此查询每月失败一次，如何重构？
【发布时间】：2018-02-16 07:54:25
【问题描述】：

此查询每月失败一次，因为 BETWEEN 部分无效。 value BETWEEN min AND max，在 3 月 1 日，我的查询将再次失败，因为它将计算为 partition_2 BETWEEN 28 AND 1。如何使这个查询更可靠但仍然只使用所需的分区？

WITH recent_tasks AS
(SELECT task_id, state, timestamp, partition_0, partition_1, partition_2,
  row_number() OVER (PARTITION BY task_id
               ORDER BY timestamp DESC) AS rn
FROM firehose
WHERE
 "partition_0" BETWEEN to_char(current_date - interval '1' day, 'yyyy') AND to_char(current_date, 'yyyy')
 and "partition_1" BETWEEN to_char(current_date - interval '1' day, 'mm') AND to_char(current_date, 'mm')
 and "partition_2" BETWEEN to_char(current_date - interval '1' day, 'dd') AND to_char(current_date, 'dd')
ORDER BY rn)
SELECT * FROM recent_tasks
WHERE rn=1

几个注意事项：

分区是字符值而不是整数
partition_2 是月份分区
查询的目的是查找每个 task_id 的最新状态
使用 AWS Athena
数据以 S3 /yyyy/mm/dd 格式存储，每天都是一个新分区

理想情况下，我的查询将正确处理每月转换：

BETWEEN FEB 10 AND FEB 11 (works with above)
BETWEEN FEB 28 AND MAR 1  (fails with above)
BETWEEN MAR 1 AND MAR 2   (works with above)

【问题讨论】：

WITH recent_tasks AS (SELECT task_id, state, timestamp, partition_0, partition_1, partition_2, row_number() OVER (PARTITION BY task_id 仅受 MySQL 8.0 支持。而且 MySQL 8.0 还没有准备好生产。你确定你在使用 MySQL？

标签： presto amazon-athena

【解决方案1】：

如果您希望实现零而不是 28：

cast(to_char(current_date, 'dd') as signed)-1

所以，在 03/01，这将返回一个 1 - to_char(current_date, 'dd')，然后减去它会给你一个零：

and "partition_2" BETWEEN to_char(cast(to_char(current_date, 'dd') as signed)-1) AND to_char(current_date, 'dd')

【讨论】：