POSTGRESQL group by for interval

Question

我有一个查询，其中我有一个单位的电灯开关打开的时间，开关(开始)时间和开关(结束)时间。

我想知道有多少个电灯开关开着，有人知道我该怎么做吗？

查询示例：

Select Flat, ID_light, start, end, 1 as ON
from lights

I/O示例：

输入数据：

Flat    Id Light    Start   End On
1   1   01/01/2021 00:00:15 01/01/2021 00:59:00 1
1   2   01/01/2021 00:00:15 01/01/2021 01:59:00 1
2   1   01/01/2021 00:00:15 01/01/2021 00:01:15 1
2   1   01/01/2021 00:02:00 01/01/2021 01:00:00 1
2   2   01/01/2021 00:00:00 01/01/2021 08:00:00 1

文本输出：

Flat    Start   End Lights On
1   01/01/2021 00:00:15 01/01/2021 00:59:00 2
1   01/01/2021 00:59:00 01/01/2021 01:59:00 1
2   01/01/2021 00:00:00 01/01/2021 00:00:15 1
2   01/01/2021 00:00:15 01/01/2021 00:01:15 2
2   01/01/2021 00:01:15 01/01/2021 00:02:00 1
2   01/01/2021 00:02:00 01/01/2021 01:00:00 2
2   01/01/2021 01:00:00 01/01/2021 08:00:00 1

Answer 1

range数据类型简化了这一过程。

获取所有单位和时间：

with times as (
  select flat, start as ts from lights
  union
  select flat, end_ from lights
),

使用lead()为每个间隔构造行

 all_ivals as (
  select flat, ts as start, 
         lead(ts) over (partition by flat 
                            order by ts) as end_
    from times
)

使用范围重叠&&运算符连接回原始表并进行聚合：

select a.flat, a.start, a.end_, count(*) as lights_on
  from all_ivals a
       join lights l
         on tsrange(l.start, l.end_, '[)') && tsrange(a.start, a.end_, '[)')
        and l.flat = a.flat
 where a.end_ is not null
 group by a.flat, a.start, a.end_
 order by a.flat, a.start
 ;

结果：

flat start               end_                lights_on
1    2021-01-01 00:00:15 2021-01-01 00:59:00         2
1    2021-01-01 00:59:00 2021-01-01 01:59:00         1
2    2021-01-01 00:00:00 2021-01-01 00:00:15         1
2    2021-01-01 00:00:15 2021-01-01 00:01:15         2
2    2021-01-01 00:01:15 2021-01-01 00:02:00         1
2    2021-01-01 00:02:00 2021-01-01 01:00:00         2
2    2021-01-01 01:00:00 2021-01-01 08:00:00         1
7 rows

Working fiddle