我需要用几分钟来划分一些日期间隔。 (例如2012-01-01 10:00 - 2012-01-01 10:00间隔应分为2012-01-01 10:01,2012-01-01 10:02,... 2012-01 -01 10:10)。 例如,有一个表在Sql Server中加速划分日期间隔数分钟
CREATE TABLE [dbo].[Events](
[ID] [int] IDENTITY(1,1) NOT NULL,
[EventStart] [datetime] NOT NULL,
[EventEnd] [datetime] NOT NULL,
[Amount] [float] NOT NULL,
CONSTRAINT [PK_Events] PRIMARY KEY CLUSTERED
(
[ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
这台充满像
DECLARE @i integer = 0;
DECLARE @initial_date datetime = '2012-01-01';
WHILE @i < 50000
BEGIN
INSERT INTO [Events] (EventStart, EventEnd, Amount) VALUES (DATEADD(MINUTE, 10*@i, @initial_date), DATEADD(MINUTE, 10*(@i + 1), @initial_date), @i);
SET @i = @i + 1;
END
因此,我们有10周多分钟的间隔。
要通过我用下面的递归CTE分钟将其划分:
DECLARE @start_date datetime = '2012-01-01';
DECLARE @end_date datetime = '2013-01-02';
WITH Date_Ranges (StatDate, Amount, IntervalStart, CurrentMinute) AS (
SELECT
DATEADD(MINUTE, 0, ev.EventStart) AS StatDate, ev.Amount, ev.EventStart AS IntervalStart, 1 AS CurrentMinute
FROM [Events] ev
WHERE ev.EventStart BETWEEN @start_date AND @end_date
UNION ALL
SELECT
DATEADD(MINUTE, CurrentMinute, ev.EventStart), ev.Amount, ev.EventStart AS IntervalStart, CurrentMinute + 1
FROM [Events] ev
INNER JOIN Date_Ranges ranges ON (ranges.IntervalStart = ev.EventStart AND
ranges.StatDate >= ev.EventStart AND
ranges.StatDate < ev.EventEnd)
WHERE DATEADD(MINUTE, CurrentMinute, ev.EventStart) BETWEEN @start_date AND @end_date AND
ev.EventStart BETWEEN @start_date AND @end_date
)
SELECT *
FROM Date_Ranges --ORDER BY StatDate
的主要问题是在大数据量这个递归CTE的太慢执行。
那么,我该如何加速呢?
谢谢。那是我需要的。在我的真实数据中,它多次比递归CTE更快。 – eternity