Question

CREATE TABLE test2 (
id INTEGER,
name VARCHAR(10),
family VARCHAR(10),
amount INTEGER)

CREATE VIEW dbo.test2_v WITH SCHEMABINDING 
AS
SELECT id, SUM(amount) as amount
-- , COUNT_BIG(*) as tmp
FROM dbo.test2 
GROUP BY id

CREATE UNIQUE CLUSTERED INDEX vIdx ON test2_v(id)

I have error with this code:

Cannot create index on view
‘test.dbo.test2_v’ because its select
list does not include a proper use of
COUNT_BIG. Consider adding
COUNT_BIG(*) to select list.

I can create view like this:

CREATE VIEW dbo.test2_v WITH SCHEMABINDING 
    AS
    SELECT id, SUM(amount) as amount, COUNT_BIG(*) as tmp
    FROM dbo.test2 
    GROUP BY id

But I’m just wondering what is purpose of this column in this case?

Answer 1

You need COUNT_BIG in this case because of the fact you are using GROUP BY.

This is one of many limitations of Indexed Views and because of these restrictions, Indexed Views can’t be used in many places or the usage of it is NOT as effective as it could have been. Unfortunately, it is how it works currently. Sucks, it narrows the scope of usage.

http://technet.microsoft.com/en-us/library/cc917715.aspx