I support the idea of using CONTEXT_INFO for this.

But I'd suggest limiting the use of it to a single, predefined byte location. And also not destroying any unused in CONTEXT_INFO when you set it: you never know, you might be wiping out something used by another process or trigger.

Since it's a pain to "implant"/stuff binary values to certain byte(s), I use a function to generate the new CONTEXT_INFO value with the byte(s) provided "stuffed" into the byte location specified:

USE Utility_Db

GO

CREATE FUNCTION [dbo].[SetContextInfo] (

@start int,

@value varbinary(128)

)

RETURNS varbinary(128)

AS

--SELECT dbo.SetContextInfo ( 10, 0xA1B2C3D4 ) --sample call that sets 4 bytes, starting at

--byte 10, other bytes are left unchanged; can set anywhere from 1 to 128 bytes

BEGIN

RETURN (

SELECT

COALESCE(SUBSTRING(CONTEXT_INFO(), 1, @start - 1), CAST(REPLICATE(0x00, @start - 1) AS varbinary(128))) +

@value +

COALESCE(SUBSTRING(CONTEXT_INFO(), @start + DATALENGTH(@value), 128 - @start - DATALENGTH(@value) + 1), 0x)

)

END --FUNCTION

GO

--Then in the set up code:

USE data_db

DECLARE @context_info varbinary(128)

SET @context_info = Utility_Db.dbo.SetContextInfo ( 10, 0xEE ) --starting byte, new value

SET CONTEXT_INFO @context_info

GO

--Finally, in the query that checks CONTEXT_INFO,

-- you can use a variable, as shown in the other code posted above;

-- or, if you prefer, you can just test CONTEXT_INFO directly:

...

and ISNULL(SUBSTRING(CONTEXT_INFO(), 10, 1), 0x00) <> 0xEE