[转]SQL小技巧－清除日志文件

Code

/* 本文由微软新闻组摘录下来的。一段非常有用的脚本。

如果碰到日志文件过大的问题，用SHIRNK DATABASE， TRUNCATE LOG FILE不是很有效时，可以考虑试下下面的脚本。把代码COPY到查询分析器里，然后修改其中的3个参数(数据库名，日志文件名，和目标日志文件的大小)，运行即可

*/

----------------------------------------------------------------------------------

SET NOCOUNT ON

DECLARE @LogicalFileName sysname, --日志文件名

@MaxMinutes INT, --允许此脚本执行的最长时间

@NewSize INT --目标日志文件的大小

USE CRM -- 要操作的数据库名

SELECT @LogicalFileName = 'CRM_LOG', -- 日志文件名

@MaxMinutes = 10, -- Limit on time allowed to wrap log.

@NewSize = 1 -- 想要收缩到的目标大小(单位M),此处标记收缩到1M

DECLARE @OriginalSize int

SELECT @OriginalSize = size

FROM sysfiles

WHERE name = @LogicalFileName

SELECT 'Original Size of ' + db_name() + ' LOG is ' +

CONVERT(VARCHAR(30),@OriginalSize) + ' 8K pages or ' +

CONVERT(VARCHAR(30),(@OriginalSize*8/1024)) + 'MB'

FROM sysfiles

WHERE name = @LogicalFileName

CREATE TABLE DummyTrans(DummyColumn char (8000) not null)

DECLARE @Counter INT,

@StartTime DATETIME,

@TruncLog VARCHAR(255)

SELECT @StartTime = GETDATE(),

@TruncLog = 'BACKUP LOG ' + db_name() + ' WITH TRUNCATE_ONLY'

DBCC SHRINKFILE (@LogicalFileName, @NewSize)

EXEC (@TruncLog)

-- Wrap the log if necessary.

WHILE @MaxMinutes > DATEDIFF (mi, @StartTime, GETDATE()) -- time has not expired

AND @OriginalSize = (SELECT size FROM sysfiles WHERE name =

@LogicalFileName)

AND (@OriginalSize * 8 /1024) > @NewSize

BEGIN -- Outer loop.

SELECT @Counter = 0

WHILE ((@Counter < @OriginalSize / 16) AND (@Counter < 50000))

BEGIN -- update

INSERT DummyTrans VALUES ('Fill Log')

DELETE DummyTrans

SELECT @Counter = @Counter + 1

END

EXEC (@TruncLog)

END

SELECT 'Final Size of ' + db_name() + ' LOG is ' +

CONVERT(VARCHAR(30),size) + ' 8K pages or ' +

CONVERT(VARCHAR(30),(size*8/1024)) + 'MB'

FROM sysfiles

WHERE name = @LogicalFileName

DROP TABLE DummyTrans

SET NOCOUNT OFF