sql-server - 根据每 n 个时间间隔选择行

Question

我有一个表，其中包含主键(bigint)、日期时间、值、外键到配置表，该表由 100,000 行组成。我希望能够获取可变时间间隔的行。例如。

    Select Timestamp, value from myTable where configID=3 
    AND{most recent for 15 min interval}

我有一个 CTE 查询，它返回间隔间隔内的多行

    WITH Time_Interval(timestamp, value, minutes)
    AS
    (
       Select   timestamp, value, DatePart(Minute, Timestamp) from  myTable 
       Where Timestamp >= '12/01/2012' and Timestamp <= 'Jan 10, 2013' and 
       ConfigID = 435 and (DatePart(Minute, Timestamp) % 15) = 0
    )
    Select Timestamp, value, minutes from Time_Interval
    group by minutes, value, timestamp
    order by Timestamp

如:

  2012-12-19 18:15:22.040   6.98    15
  2012-12-19 18:15:29.887   6.98    15
  2012-12-19 18:15:33.480   7.02    15
  2012-12-19 18:15:49.370   7.01    15
  2012-12-19 18:30:41.920   6.95    30
  2012-12-19 18:30:52.437   6.93    30
  2012-12-19 19:15:18.467   7.13    15
  2012-12-19 19:15:34.250   7.11    15
  2012-12-19 19:15:49.813   7.12    15

但可以看出，第一个 15 分钟间隔有 4 个，下一个间隔有 2 个，依此类推...更糟糕的是，如果在 15 分钟的精确时间戳处没有获取到数据，则没有任何值(value)。

我想要的是十五分钟间隔的最新值...如果该间隔的唯一数据发生在间隔开始后 1 秒。

我正在考虑 Lead/over，但是再次......行并不是这样组织的。主键是一个bigInt，并且是一个聚集索引。 Timstamp 列和 ConfigID 列均已建立索引。上述查询在一秒内返回 4583 行。

感谢您的帮助。

Answer 1

试穿一下尺寸。当给定间隔有多个时间戳时，它甚至可以处理返回一行。注意:这假设您的 Bigint PK 列名为:idx。如果不是，只需替换您看到“idx”的位置即可。

    ;WITH Interval_Helper([minute],minute_group)
    AS
    (
              SELECT  0, 1 UNION SELECT  1, 1 UNION SELECT  2, 1 UNION SELECT  3, 1 UNION SELECT  4, 1
        UNION SELECT  5, 1 UNION SELECT  6, 1 UNION SELECT  7, 1 UNION SELECT  8, 1 UNION SELECT  9, 1
        UNION SELECT 10, 1 UNION SELECT 11, 1 UNION SELECT 12, 1 UNION SELECT 13, 1 UNION SELECT 14, 1
        UNION SELECT 15, 2 UNION SELECT 16, 2 UNION SELECT 17, 2 UNION SELECT 18, 2 UNION SELECT 19, 2
        UNION SELECT 20, 2 UNION SELECT 21, 2 UNION SELECT 22, 2 UNION SELECT 23, 2 UNION SELECT 24, 2
        UNION SELECT 25, 2 UNION SELECT 26, 2 UNION SELECT 27, 2 UNION SELECT 28, 2 UNION SELECT 29, 2
        UNION SELECT 30, 3 UNION SELECT 31, 3 UNION SELECT 32, 3 UNION SELECT 33, 3 UNION SELECT 34, 3
        UNION SELECT 35, 3 UNION SELECT 36, 3 UNION SELECT 37, 3 UNION SELECT 38, 3 UNION SELECT 39, 3
        UNION SELECT 40, 3 UNION SELECT 41, 3 UNION SELECT 42, 3 UNION SELECT 43, 3 UNION SELECT 44, 3
        UNION SELECT 45, 4 UNION SELECT 46, 4 UNION SELECT 47, 4 UNION SELECT 48, 4 UNION SELECT 49, 4
        UNION SELECT 50, 4 UNION SELECT 51, 4 UNION SELECT 52, 4 UNION SELECT 53, 4 UNION SELECT 54, 4
        UNION SELECT 55, 4 UNION SELECT 56, 4 UNION SELECT 57, 4 UNION SELECT 58, 4 UNION SELECT 59, 4

    )
    ,Time_Interval([timestamp], value, [date], [hour], minute_group)
    AS
    (
       SELECT A.[Timestamp]
             ,A.value
             ,CONVERT(smalldatetime, CONVERT(char(10), A.[Timestamp], 101))
             ,DATEPART(HOUR, A.[Timestamp])
             ,B.minute_group
         FROM  myTable A
         JOIN Interval_Helper B
           ON (DATEPART(minute, A.[Timestamp])) = B.[minute]
          AND A.[Timestamp] >= '12/01/2012' 
          AND A.[Timestamp] <= '01/10/2013' 
          AND A.ConfigID = 435 
    )
    ,Time_Interval_TimeGroup([date], [hour], [minute], MaxTimestamp)
    AS
    (
        SELECT [date]
              ,[hour]
              ,minute_group
              ,MAX([Timestamp]) as MaxTimestamp
          FROM Time_Interval
         GROUP BY [date]
              ,[hour]
              ,minute_group
    )
    ,Time_Interval_TimeGroup_Latest(MaxTimestamp, MaxIdx)
    AS
    (
        SELECT MaxTimestamp
              ,MAX(idx) as MaxIdx
          FROM myTable A
          JOIN Time_Interval_TimeGroup B
            ON A.[Timestamp] = B.MaxTimestamp
         GROUP BY MaxTimestamp
    )


    SELECT A.*
      FROM myTable A
      JOIN Time_Interval_TimeGroup_Latest B
        ON A.idx = B.MaxIdx
     ORDER BY A.[timestamp]   

<小时/>

这是来自@MntManChris 的巧妙时间组函数的另一种表现:

CREATE FUNCTION dbo.fGetTimeGroup (@DatePart tinyint, @Date datetime)
RETURNS int
AS
BEGIN
RETURN CASE @DatePart
            WHEN 1 THEN DATEPART(mi, @Date)
            WHEN 2 THEN DATEPART(mi, @Date)/5 + 1   --  5 min
            WHEN 3 THEN DATEPART(mi, @Date)/15 + 1  -- 15 min
            WHEN 4 THEN DATEPART(mi, @Date)/30 + 1  -- 30 min
            WHEN 5 THEN DATEPART(hh, @Date)         -- hr
            WHEN 6 THEN DATEPART(hh, @Date)/6 + 1   -- 6 hours
            WHEN 7 THEN DATEPART(hh, @Date)/12 + 1  -- 12 hours
            WHEN 8 THEN DATEPART(d, @Date)          -- day
            ELSE -1
        END
END