根据每 20 秒窗口的时间戳对记录进行分组

Question

我有下面的 PLSQL 查询，根据时间戳的输入范围返回一些时间戳列表。

select data_timestamp 
  from table1
 where data_timestamp > :input_start_ts
   and data_timestamp < :input_end_ts;

**输出：**

2024-07-10 10:21:10
2024-07-10 10:21:18
2024-07-10 10:21:21
2024-07-10 10:21:22
2024-07-10 10:21:23
2024-07-10 10:21:25
2024-07-10 10:21:26
2024-07-10 10:21:29
2024-07-10 10:21:30
2024-07-10 10:21:31
2024-07-10 10:21:32
2024-07-10 10:21:40
2024-07-10 10:21:49
2024-07-10 10:21:55
2024-07-10 10:21:56
2024-07-10 10:22:01
2024-07-10 10:22:40

我正在尝试将这些时间戳分组为 20 秒窗口，并为该组指示器添加新列：

• 预期输出：

    2024-07-10 10:21:10    1
    2024-07-10 10:21:18    1
    2024-07-10 10:21:21    1
    2024-07-10 10:21:22    1
    2024-07-10 10:21:23    1
    2024-07-10 10:21:25    1
    2024-07-10 10:21:26    1
    2024-07-10 10:21:29    1
    2024-07-10 10:21:30    2
    2024-07-10 10:21:31    2
    2024-07-10 10:21:32    2
    2024-07-10 10:21:40    2
    2024-07-10 10:21:49    2
    2024-07-10 10:21:55    3
    2024-07-10 10:21:56    3
    2024-07-10 10:22:01    3
    2024-07-10 10:22:40    4
  

你能引导我走向正确的方向吗

Answer 1

您的问题不完全清楚，“20秒窗口”是什么意思。这个窗口应该从哪里开始？总是在第一排？

起点是这样的：

WITH t AS ( 
    SELECT data_timestamp, 
        TRUNC(data_timestamp, 'mi') + TRUNC(EXTRACT(SECOND FROM data_timestamp) / 20) * INTERVAL '20' SECOND AS data_interval
    FROM table1)
SELECT data_timestamp, data_interval,
    DENSE_RANK() OVER (ORDER BY data_interval)
FROM t;
    

我想你需要添加一些偏移量，就是这个：

WITH t AS ( 
    SELECT data_timestamp, 
        TRUNC(data_timestamp, 'mi') + TRUNC(EXTRACT(SECOND FROM data_timestamp) / 20) * INTERVAL '20' SECOND
        + EXTRACT(SECOND FROM MIN(chng_date_implemented) OVER ())  * INTERVAL '1' SECOND AS data_interval
    FROM table1)
SELECT data_timestamp, data_interval,
    DENSE_RANK() OVER (ORDER BY data_interval)
FROM t;

注意，上述查询适用于数据类型

TIMESTAMP

。如果您的表使用数据类型

DATE

那么您必须使用

CAST(data_timestamp AS TIMESTAMP)