How to Select UNCOMMITTED rows only in SQL Server?

Question

I am working on DW project where I need to query live CRM system. The standard isolation level negatively influences performance. I am tempted to use no lock/transaction isolation level read uncommitted. I want to know how many of selected rows are identified by dirty read.

Answer 1

Maybe you can do this:

SELECT * FROM T WITH (SNAPSHOT)
EXCEPT
SELECT * FROM T WITH (READCOMMITTED, READPAST)

But this is inherently racy.