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clr enabled Server Configuration Option

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Applies to: SQL Server

Use the clr enabled option to specify whether user assemblies can be run by SQL Server. The clr enabled option provides the following values:

Value Description
0 Assembly execution not allowed on SQL Server.
1 Assembly execution allowed on SQL Server.

For WOW64 only: restart WOW64 servers to apply these changes. No restart required for other server types.

When you run RECONFIGURE, and the run value of the clr enabled option is changed from 1 to 0, all application domains containing user assemblies are immediately unloaded.

Important

Common language runtime (CLR) execution is not supported under lightweight pooling Disable one of two options: "clr enabled" or "lightweight pooling". Features that rely upon CLR and that do not work properly in fiber mode include the hierarchyid data type, the FORMAT function, replication, and Policy-Based Management. For more information, see lightweight pooling Server Configuration Option

Warning

CLR uses Code Access Security (CAS) in the .NET Framework, which is no longer supported as a security boundary. A CLR assembly created with PERMISSION_SET = SAFE may be able to access external system resources, call unmanaged code, and acquire sysadmin privileges. Beginning with SQL Server 2017 (14.x), an sp_configure option called clr strict security is introduced to enhance the security of CLR assemblies. clr strict security is enabled by default, and treats SAFE and EXTERNAL_ACCESS assemblies as if they were marked UNSAFE. The clr strict security option can be disabled for backward compatibility, but this is not recommended. Microsoft recommends that all assemblies be signed by a certificate or asymmetric key with a corresponding login that has been granted UNSAFE ASSEMBLY permission in the master database. SQL Server administrators can also add assemblies to a list of assemblies, which the Database Engine should trust. For more information, see sys.sp_add_trusted_assembly.

Note

Though the clr enabled configuration option is enabled in Azure SQL Database, developing CLR user functions are not supported in Azure SQL Database.

Example

The following example first displays the current setting of the clr enabled option and then enables the option by setting the option value to 1. To disable the option, set the value to 0.

EXEC sp_configure 'clr enabled';  
EXEC sp_configure 'clr enabled' , '1';  
RECONFIGURE;

Next steps