Postgres 发现转换

Question

我正在尝试查找系统处于特定状态的所有时间段。状态登录到table。数据示例如下：

Time - State  
12:00 - 1  
12:01 - 1  
12:02 - 1  
12:03 - 1  
12:04 - 0  
12:05 - 0  
12:06 - 0  
12:07 - 1  
12:08 - 1

我希望看到的结果是：

Start - End - State  
12:00 - 12:03 - 1  
12:04 - 12:06 - 0  
12:07 - 12:08 - 1

是否有任何预定义的函数来查找转换记录？

Answer 1

像这样的东西应该可以工作：

SELECT "State",
       MIN("Time") AS Start,
       MAX("Time") AS End     
FROM (
  SELECT "Time", "State",
         ROW_NUMBER() OVER (ORDER BY "Time") - 
         ROW_NUMBER() OVER (PARTITION BY "State" ORDER BY "Time") AS grp
  FROM mytable) AS t
GROUP BY "State", grp

内部查询使用标准技术来识别具有相同 State 值的岛连续记录。外部查询使用计算列 grp 到 GROUP BY 并获取每个 island.

的 Start、End 值

Postgres 发现转换

Postgres finding transitions

sql

postgresql

gaps-and-islands