Setting SQL Server CONTEXT_INFO In Power Query

In my quest to check out every last bit of obscure Power Query functionality, this week I looked into the ContextInfo option on the Sql.Database and Sql.Databases M functions. This option allows you to set CONTEXT_INFO in SQL Server (see here for a good article explaining what this is) and here’s an example of how to use it:

let
  Source = Sql.Database(
    "localhost", 
    "AdventureWorksDW2017", 
    [
      Query = "SELECT * FROM DIMDATE", 
      ContextInfo = Text.ToBinary(
        "Hello"
      )
    ]
  )
in
  Source

This Power Query query runs a simple SQL SELECT statement against the SQL Server Adventure Works DW 2017 database. Note that since you need to pass a binary value to the ContextInfo option, in this example I had to use the Text.ToBinary function to convert my text to binary.

Here’s what happens in SQL Server when this Power Query query is run:

Here’s a simple example of how to retrieve this data on the SQL Server side:

SELECT session_id, login_time, program_name, context_info 
FROM sys.dm_exec_sessions
WHERE session_id=57

I’ll leave it to the SQL Server experts to decide what this can be used for and no doubt to complain that it would be more useful to support SESSION_CONTEXT too – although I’ve heard that might already be used for something, so I need to do more research here…