Category: Filtered Statistics

Indexed Views In SQL Server: No Filtered Indexes Or Filtered Statistics

Posted on by Erik Darling

Half Baked

In my quest to love indexed views more, I’m always trying new things with them to solve problems.

Occasionally, I am pleasantly surprised by what can be accomplished with them. Occasionally.

Today was not an occasion. Let’s take an unfortunate look.

CREATE TABLE
    dbo.IndexedViewMe
(
    id int PRIMARY KEY CLUSTERED
);
GO 

CREATE VIEW 
    dbo.TheIndexedView
WITH SCHEMABINDING
AS
SELECT
    ivm.id
FROM dbo.IndexedViewMe AS ivm;
GO 

CREATE UNIQUE CLUSTERED INDEX
    uqi
ON dbo.TheIndexedView
    (id);

INSERT 
    dbo.IndexedViewMe
(
    id
)
SELECT
    x.c
FROM 
(
    SELECT 1 
      UNION ALL 
    SELECT 2
) AS x(c);

This gives us a tiny little table and indexed view. If we try to do either of these things, it doesn’t go well:

CREATE INDEX 
    i
ON dbo.TheIndexedView
    (id)
WHERE 
    id = 2;

Msg 10610, Level 16, State 1, Line 40

Filtered index ‘i’ cannot be created on object ‘dbo.TheIndexedView’ because it is not a user table. Filtered indexes are only supported on tables.

If you are trying to create a filtered index on a view, consider creating an indexed view with the filter expression incorporated in the view definition.

CREATE STATISTICS 
    s
ON dbo.TheIndexedView
    (id)
WHERE 
    id = 2;

Msg 10623, Level 16, State 1, Line 47

Filtered statistics ‘s’ cannot be created on object ‘dbo.TheIndexedView’ because it is not a user table. Filtered statistics are only supported on user tables.

Sort of a bummer, that. And it strikes me that it’s an odd limitation — especially for the statistics — but what can you do?

Indexed views haven’t changed aside from bug fixes in forever and a day. I doubt there’ll be any real investment in enhancing them anytime soon.

Thanks for reading!

Going Further

If this is the kind of SQL Server stuff you love learning about, you’ll love my training. I’m offering a 75% discount to my blog readers if you click from here. I’m also available for consulting if you just don’t have time for that and need to solve performance problems quickly.