sp_set_session_context (Transact-SQL)

Article
05/23/2023

Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics SQL analytics endpoint in Microsoft Fabric Warehouse in Microsoft Fabric

Sets a key-value pair in the session context.

Transact-SQL syntax conventions

Syntax

sp_set_session_context [ @key= ] N'key', [ @value= ] 'value'  
    [ , [ @read_only = ] { 0 | 1 } ]  
[ ; ]

Arguments

[ @key= ] N'key'
The key being set, of type sysname. The maximum key size is 128 bytes.

[ @value= ] 'value'
The value for the specified key, of type sql_variant. Setting a value of NULL frees the memory. The maximum size is 8,000 bytes.

[ @read_only= ] { 0 | 1 }
A flag of type bit. If 1, then the value for the specified key cannot be changed again on this logical connection. If 0 (default), then the value can be changed.

Permissions

Any user can set a session context for their session.

Remarks

Like other stored procedures, only literals and variables (not expressions or function calls) can be passed as parameters.

The total size of the session context is limited to 1 MB. If you set a value that causes this limit to be exceeded, the statement fails. You can monitor overall memory usage in sys.dm_os_memory_objects (Transact-SQL).

You can monitor overall memory usage by querying sys.dm_os_memory_cache_counters (Transact-SQL) as follows: SELECT * FROM sys.dm_os_memory_cache_counters WHERE type = 'CACHESTORE_SESSION_CONTEXT';

Examples

A. The following example shows how to set and then return a sessions context key named language with a value of English.

EXEC sys.sp_set_session_context @key = N'language', @value = 'English';  
SELECT SESSION_CONTEXT(N'language');

The following example demonstrates the use of the optional read-only flag.

EXEC sys.sp_set_session_context @key = N'user_id', @value = 4, @read_only = 1;

B. The following example shows how to set and retrieve a session context key named the client_correlation_id with a value of 12323ad.

-- set value
EXEC sp_set_session_context 'client_correlation_id', '12323ad'; 

--check value
SELECT SESSION_CONTEXT(N'client_correlation_id');