sql - Sql Server 2008 清除 Select 语句缓存？

Question

执行 select 语句后是否有可能清除缓存？

我尝试使用我的一个 sql，第一次执行它，它返回我 3.15 分钟，第二次（dint 改变任何东西）它返回我 2.55 分钟。

测试sql的实际性能对我来说有点乏味。

我在这篇文章中发现 Sql Server 2005 上有缓存。

我对 sql server 2008 上的缓存是否正确？

Answer 1

这就是我出于相同目的所做的事情：

DBCC FREEPROCCACHE
DBCC DROPCLEANBUFFERS
GO
DROP TABLE [WHATEVER I NEED TO DROP]
GO
TRUNCATE TABLE [WHATEVER I NEED TO EMPTY]
GO
UPDATE [WHATEVER HAS TO BE "RESET"]
GO
[DO REST OF "RESET ACTIONS" HERE]
USE [YOUR DATABASE NAME]
GO


DECLARE @start_time datetime, @end_time datetime, @miliseconds int

DECLARE @ALL_YOUR_VARS -- _YOU'LL_USE_WHILE_YOU_MEASURE
/* BECAUSE YOU DON'T WANT TO MEASURE THE TIME SPENT ON TEMP VARS YOU CREATE FOR MEASURING EXEC TIME ONLY */

-- TODO: SET VARS' VALUES HERE, SAME REASON AS ABOVE

SET @start_time = GETDATE()

-- [EXECUTE ALL YOUR STATEMENTS HERE]
-- [YOU WANT TO MEASURE]

SET @end_time = GETDATE() 
SET @miliseconds = DATEDIFF(ms, @start_time, @end_time)
SELECT @start_time, @end_time, CAST(@miliseconds AS VARCHAR(max)) + ' ms'
GO

编辑：差点忘了！您还可以在开始测量之前删除与数据库的所有活动连接（不要忘记在执行下面的代码作为实际即时窗口后创建一个新连接，从中运行查询也将断开连接！！！）

USE master
GO


SET NOCOUNT ON
DECLARE @DBName varchar(50)
DECLARE @spidstr varchar(8000)
DECLARE @ConnKilled smallint
SET @ConnKilled=0
SET @spidstr = ''

Set @DBName = 'YOURDBNAMEHERE'
IF db_id(@DBName) < 4
BEGIN
PRINT 'Connections to system databases cannot be killed'
RETURN
END
SELECT @spidstr=coalesce(@spidstr,',' )+'kill '+convert(varchar, spid)+ '; '
FROM master..sysprocesses WHERE dbid=db_id(@DBName)

IF LEN(@spidstr) > 0
BEGIN
EXEC(@spidstr)
SELECT @ConnKilled = COUNT(1)
FROM master..sysprocesses WHERE dbid=db_id(@DBName)
END