Question

我有27张机器过程数据表，其中包含cols：id，timestamp，col1..col70 +和最多400万行。采样率从每10秒1次变为每30秒1次。如何删除每个表中的行（独立），其中任何行的时间戳在前一个时间戳的21秒内（有效地将所有行的采样率更改为1/30秒）？不要假设“id”或“timestamp”是任何顺序，没有外键，“id”是标识和主键列。这些是非关系的历史数据表。这些是来自一个表的一些行作为示例。在样本间隔的早期是10秒，现在是30秒。

id        Timestamp
949046  2015-03-02 02:54:49.740   --(arbitrarily starting here)
949047  2015-03-02 02:54:59.757   --delete - within 21 secs of 949046
949048  2015-03-02 02:55:09.757   --delete - within 21 secs of 949046
949049  2015-03-02 02:55:19.757   --keep - > 21 secs from 949046
949050  2015-03-02 02:55:29.727   --delete - within 21 secs of **949049**
949051  2015-03-02 02:55:39.727   --delete - within 21 secs of 949049
949052  2015-03-02 02:55:49.743   --keep - > 21 secs from 949049
949053  2015-03-02 02:55:59.727   --delete - within 21 secs of **949052**
.
.
3370919 2016-10-22 10:26:23.510   --keep assuming > 21 secs from previous row
3370920 2016-10-22 10:26:53.570   --keep - > 21 secs from 3370919
3370921 2016-10-22 10:27:23.617   --keep - > 21 secs from 3370920

Answer 1

您是否尝试过使用？

DECLARE @vdate VARCHAR(24);

SELECT @vdate=CONVERT(VARCHAR(10),TimeStamp,103)+' '+CONVERT(VARCHAR(5),TimeStamp,108)+':30';

DELETE FROM TABLE WHERE TimeStamp BETWEEN @TimeStampCurrent AND @vdate

Answer 2

为了不让这个开放，这就是我用TT作为测试表和SQL Server 2012的想法：

Drop table TT
Select *, row_number() over (order by timestamp) RN
into TT 
from MyTable

使col RN成为主键列（执行时间减少30 +）

循环解决方案：

declare @LowWindow datetime = (Select timestamp from TT where RN=1 ), 
    @HiWindow datetime = (dateadd(ss,21,(Select timestamp from TT where RN=1))), 
    @MaxLoop int = (select top (1) count(id) from TT),
    @LoopCount int = 1

Loop1:

if ((select timestamp from TT where RN = @LoopCount+1) > @LowWindow and (select timestamp from TT where RN = @LoopCount+1)< @HiWindow)
    Begin
        Delete from TT where rn = @LoopCount + 1
        Set @LoopCount = @LoopCount + 1
    End

Else 
    begin
        set @LoopCount = @LoopCount + 1
        set @LowWindow = (select timestamp from TT where RN = @LoopCount)
        set @HiWindow = (dateadd(ss,21, @LowWindow))
    end

if (@LoopCount > @Maxloop)
    goto EndQuery
Else 
    GOTO Loop1

EndQuery:

从TT删除PK约束并从TT中删除col RN，将MyTable替换为TT，在MyTable中恢复对col ID的PK约束。

在3,367,000行，980MB的表上执行1小时54分钟。随意评论。

我很想看到一套理论解决方案！

SQL - 如果在上一行的时间间隔内，则删除行

2 个答案: