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Thursday, May 21, 2009 | 
Well, shrinking log file manually and frequently is not at all good idea but we have to do it once in a while when it reaches at very big size, however if it is growing unacceptably and frequently, you have to investigate the reason before shrinking it.
Anyway, our main focus today is how to shrink log file. Well, there is a simple command “DBCC SHRINKFILE” in T-SQL but what, if we want to shrink log file of all database in SQL Server? Well in this situation SP_MsForEachDB (undocumented SP) will come to your help.
Let us see small yet handy script to do so:
use master
DECLARE @SQL varchar (2000)
SELECT @SQL = ''
SELECT @SQL = @SQL + 'if ''?'' <> ''master'' and ''?'' <> ''msdb'' and ''?''<>''tempdb'' and ''?'' <> ''model'' '
SELECT @SQL = @SQL + 'BEGIN '
SELECT @SQL = @SQL + 'USE ?; '
SELECT @SQL = @SQL + 'SELECT ''?''; '
SELECT @SQL = @SQL + 'DECLARE @LogFile varchar (30); '
SELECT @SQL = @SQL + 'SELECT @LogFile = name FROM dbo.sysfiles WHERE (status & 0x40) <> 0; '
SELECT @SQL = @SQL + 'dbcc shrinkfile (@LogFile, 1,truncateonly); '
SELECT @SQL = @SQL + 'SELECT fileid, name, filename, size, growth, status, maxsize FROM dbo.sysfiles WHERE (status & 0x40) <> 0; '
SELECT @SQL = @SQL + 'END'
SELECT @SQL
EXEC sp_MSforeachdb @command1=@SQL
GO
To know more about SP_MsForEachDB stored procedure, have a look at one of my previous article at:
http://www.sqlhub.com/2009/03/spmsforeachdb-undocumented-stored.html
http://www.sqlhub.com/2009/04/find-user-in-all-database-with.html
Reference: Ritesh Shah
http://www.sqlhub.com
Note: Microsoft Books online is a default reference of all articles but examples and explanations prepared by Ritesh Shah, founder of http://www.SQLHub.com
4 comments:
You have given a ticking timebomb in the hands of people willing to believe they really should perform this massive log truncation... IMO, you should definitely mention that log truncation causes log to be fragmented and growing again (the first effect is implied by the second one). Moreover, why not to clearly state that the key to keep your log fairly small is to backup it on a regular basis?
Hi brejk,
First of all, welcome to my blog. Yes you are absolutely right. I have mentioned that it is not good to shrink the log file manually and frequently but sometime when we want to reclaim the space, we do need it as backing up log won't reclaim the physical space. I have read so many question in many forum that people need to reclaim the space and that lead me write this script in my blog.
I prefer the approach to give people not just a direct slutions to their questions but also if applicable to let them know they are heading for a disaster :-)
Yes, that is true in some cases but not for all cases as some people need it but shouldn't be apply in all case. thanks for your comments, after seeing these discussion, people will come to know that, this should be last weapon not first.
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