Compressing SQL Server Backup Files

Hello Database Professionals,

Starting with SQL Server 2008 Enterprise Edition we have the option of compressing backup files (this includes both BACKUP DATABASE and BACKUP LOG statements which mean not only database backups but log file backups will be compressed) to save disk space and also decrease the duration of the backup and restore operations. The backup compression was an enterprise edition only feature with SQL Server 2008 but with SQL Server 2008 R2 this feature is supported by standard and higher editions. So that was welcome news for me since I support number of SQL Server 2008 R2 Standard Edition.

I have been using T-SQL script to backup databases. The script checks the edition of the SQL Server and then builds the backup command to compress the backup file if it’s enterprise edition or just backups the database if it was a standard edition.

Before the end of 2011 I have completed deploying/upgrading to SQL Server 2008 R2. That meant that my script no longer needed to check the edition of SQL Server 2008 R2 since the compression is already supported in standard and higher editions. So I turned to global configurations and enable the backup compressions. I would like to remind the readers that enabling the backup compression creates additional CPU overhead which depends on you workload might impact your server performance. I suggest that you test your backup process and if necessary using Resource Governor (this is Enterprise Edition only feature) create a low priority compressed backup in a session whose CPU usage is limited by Resource Governor when CPU contention occurs.

Let’s start with checking the backup compression setting for the server by using the script below.

USE master

SELECT *

FROM sys.configurations

WHERE name = 'backup compression default'

ORDER BY name

Let’s check the returned result for the value_in_use column. This shows us the running value curently in effect for this option and is_dynamic column tells us the changes take effect after the RECONFIGURE statement executed. Now it’s time to execute the below script to enable the backup compression since the value_in_use is 0 for the server I am currently working.

USE master

EXEC SP_CONFIGURE 'backup compression default',1

RECONFIGURE

Let’s check the value_in_use by executing the first select statement.

USE master

SELECT *

FROM sys.configurations

WHERE name = 'backup compression default'

Now we should see that the value_in_use is 1 and we don’t need to use the optional keyword COMPRESSION in the backup database command.

By default when backup is compressed checksums are performed to detect media corruptions but if for any reason you need, you can explicitly disable the compression by using NO_COMPRESSION keyword in your backup statement.

I have seen anywhere from 35% to 80% compression ration and backup duration decrease from several hours to 30-45 minutes for the databases I administor. Your mileage will vary and you should TEST, TEST, TEST and deploy your changes for your environments. Here is the link to find out more about backup database command in MSDN.

HTH,

Bulent

Dropping Multiple SQL Server Objects in Single Line

As humans we try to find a way to work faster and efficient. As data professionals, typing less probably is another thing we want. My SQL Server tip today is about dropping multiple objects (tables, views, stored procedures, and even databases) in single drop statement. This is powerful but can be dangerous in production so please use caution. Here is a script that creates couple of tables and then drops both tables in single drop statement.

Sincerely,

Bulent

-- CREATE TABLES

USE tempdb

GO

CREATE TABLE dbo.TableT1 (t1c1 TINYINT)

CREATE TABLE dbo.TableT2 (t2c1 TINYINT)

GO

INSERT INTO dbo.TableT1 VALUES(1)

INSERT INTO dbo.TableT2 VALUES(2)

GO

-- CHECK THE TABLES CREATED

SELECT *

FROM sys.tables

WHERE name LIKE 'TableT_'

GO

-- DROP BOTH TABLES IN SINGLE DROP STATEMENT

DROP TABLE dbo.TableT1, dbo.TableT2

GO

-- CHECK THE TABLES DROPPED

SELECT *

FROM sys.tables

WHERE name LIKE 'TableT_'

GO