Wednesday, February 16, 2011

How to determine which version of SQL Server data access driver is used by an application

SQL Server Native Client was introduced with SQL Server 2005 and a newer version was introduced with SQL Server 2008. How do I determine which SQL Server Native Client version is being used by my SQL connections?


First of all, it is important to know what SQL Server Native Client (SNAC) is. Microsoft states that a SNAC “contains the SQL Server ODBC driver and the SQL Server OLE DB provider in one native dynamic link library (DLL) supporting applications using native-code APIs (ODBC, OLE DB and ADO) to Microsoft SQL Server.” You can read more here:

SNAC 9 was introduced with SQL Server 2005 and SNAC 10 came with SQL Server 2008. It’s important to be able to verify which version of SNAC is used by SQL connections, because there are additional features in SNAC 10 that are not supported in SNAC 9. Refer to the link in the next steps section about the differences.

It is fairly easy to identify which protocol a specific SQL session is using by looking at sys.dm_exec_connections view. The DMV sys.dm_exec_connections has a column named protocol_version, which according to BOL means “Version of the data access protocol associated with this connection”. Basically, it indicates what protocol is associated with the client connection.

You can run the following query to get a list of connections and their protocol version.

select protocol_type, protocol_version,CONVERT(binary(4),protocol_version)
from sys.dm_exec_connections

As we can see below the converted protocol is pretty cryptic.

According to the table below (source:, we are able to interpret the hexadecimal value of the protocol version. For example, values 0x730B003 indicate that this connection comes from a client using a SQL Server 2008 driver.

SQL Server Client to ServerServer to Client
7.0 0x000000700x07000000
2000 0x000000710x07010000
2000 SP1 0x010000710x71000001
2005 0x020009720x72090002
2008 0x03000B730x730B0003

To make these eaiser to read, we can rewrite our query as follows to show the driver version.

SELECT session_id, protocol_type, driver_version =
CASE SUBSTRING(CAST(protocol_version AS BINARY(4)), 1,1)
WHEN 0x70 THEN 'SQL Server 7.0'
WHEN 0x71 THEN 'SQL Server 2000'
WHEN 0x72 THEN 'SQL Server 2005'
WHEN 0x73 THEN 'SQL Server 2008'
ELSE 'Unknown driver'
END,client_net_address ,client_tcp_port,local_tcp_port ,T.text
FROM sys.dm_exec_connections
CROSS APPLY sys.dm_exec_sql_text(most_recent_sql_handle) AS T

The output below shows us that our client applications are using a SNAC 9 or SNAC 10 protocol as shown in line 1 and line 2.

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