How to shrink tempdb

There may come a time when you might want to shrink tempdb because it has become too large.

There are a few ways you can do this and I have listed them below but please read to the end of the post before making a decision on which way you want to approach this. There is an important note at the end of the post.

So first, we’ll look at the configuration on my server.

[sourcecode language=’sql’]SELECT name, size
FROM sys.master_files
WHERE database_id = DB_ID(N’tempdb’);[/sourcecode]

name                 size
-------------------- -----------
tempdev              1280
templog              640

(2 row(s) affected)

Note that the size column is listing the size of the file in 8Kb pages. In this instance my “tempdev” file is 10Mb (( 1280 * 8 ) = 10240 kb)

How to shrink tempdb using DBCC SHRINKFILE

The syntax is as follows and the operation does not require a restart of the sql server service.

DBCC SHRINKFILE(logical_filename, size_in_MB)

So I will shrink the file to 5Mb

Here is the T-SQL:

[sourcecode language=’sql’]DBCC SHRINKFILE(tempdev, 5);[/sourcecode]
Which produces the following output and I can see that CurrentSize is now smaller than previously

DbId   FileId      CurrentSize MinimumSize UsedPages   EstimatedPages
------ ----------- ----------- ----------- ----------- --------------
2      1           640         288         176         176

(1 row(s) affected)

DBCC execution completed. If DBCC printed error messages, contact your system administrator.

name                 size
-------------------- -----------
tempdev              640
templog              640

(2 row(s) affected)

Don’t try and increase filesizes in tempdb using this command because you will see an error. In this example, the attempt was to increase to 50Mb.

Cannot shrink file ‘1’ in database ‘tempdb’ to 6400 pages as it only contains 640 pages.

How to shrink tempdb using DBCC SHRINKDATABASE

The syntax is as follows and does not require a restart of the SQL Server service:

DBCC SHRINKDATABASE(tempdb, ‘target_percentage_of_free_space’);

So if the data files in tempdb had enough free space, you could shrink tempdb by running this command to leave 10Mb of free space at the end of the files:
[sourcecode language=’sql’]DBCC SHRINKDATABASE(tempdb, 10);[/sourcecode]

How to shrink tempdb using ALTER DATABASE

As in my post about moving tempdb, you can use the ALTER DATABASE command to perform a tempdb resize.

The following script will resize both the log and data file to be 100Mb.
[sourcecode language=’sql’]USE master;
GO
ALTER DATABASE tempdb
MODIFY FILE (NAME = tempdev, SIZE=100Mb);
GO
ALTER DATABASE tempdb
MODIFY FILE (NAME = templog, SIZE=100Mb);
GO[/sourcecode]

This operation requires a SQL Server service restart once the tempdb configuration has been set by ALTER DATABASE.

How to shrink tempdb using Management Studio

You can also use Management Studio to resize Tempdb and perform shrink operations by right mouse clicking the tempdb database and choosing Tasks->Shrink.

To resize tempdb, you can set the file sizes by right mouse clicking the tempdb and choosing Properties->Files and setting the sizes there.

Note that with both the ALTER DATABASE and management studio methods, you cannot resize a tempdb file to a particular size if the data contained in the file exceed the size that you are trying to size to.

Should you shrink TempDB?

It is documented in this Microsoft article that it can cause consistency errors in the TempDB database if you perform a shrink operation while the database is in use so please read this carefully and consider whether you can shrink the database by other means, i.e restarting the SQL Server instance which will create a brand new copy of TempDB releasing the disk space.

Tempdb won’t shrink?

I sometimes get asked about why tempdb won’t shrink when using one of the methods which does not involve a SQL Server service restart. Microsoft recommends that if possible, shrinking of tempdb should be done either in single user mode or when there is no current tempdb activity. I have extracted the quote below from the article that is linked to in the previous section.

It is safe to run shrink in tempdb while tempdb activity is ongoing. However, you may encounter other errors such as blocking, deadlocks, and so on that can prevent shrink from completing. Therefore, in order to make sure that a shrink of tempdb will succeed, we recommend that you do this while the server is in single-user mode or when you have stopped all tempdb activity.