In case you're using MSSQL 2008 read this:

http://social.msdn.microsoft.com/Forums/en/sqldatabaseengine/thread/54e6e281-005a-4b07-8c85-3685441f4f3d

Take a look at the last reply which worked for me in 2008:

 

For shrinking log file in sql server 2008, first u have to change the recovery model of database to simple,shrink the log file and then change back to the previous recovery model. following is the code

 

USE dbname;

GO

-- Truncate the log by changing the database recovery model to SIMPLE.

ALTER DATABASE dbname

SET RECOVERY SIMPLE;

GO

-- Shrink the truncated log file to 1 MB.

DBCC SHRINKFILE (2, 1);  -- here 2 is the file ID for trasaction log file,you can also mention the log file name (dbname_log)

GO

-- Reset the database recovery model.

ALTER DATABASE dbname

SET RECOVERY FULL;

GO

 

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Yehuda Tiram
AtarimTR

972-2-5700114   |   972-54-4525492   |    http://www.atarimtr.co.il

Lou,
The issue with search tables size is that after you truncate the tables, the search engine will again repopulate the search tables.  So no real advantage in truncating them.   Also, once you truncate the tables, the search function will cease to work.   So, if you require search, then you will have to live with the tables sizes. 

If you do not want search, you should disable the search engine in the scheduled job then you can truncate the search tables.  Recheck the table sizes after a few hours to ensure the tables have not been repopulated.  If they are then you have not stopped all the Search engine jobs.

Hope this helps
Paul.