List all index columns (including filtered ones) in SQL Server

Question

How to get all index columns including filtered columns?

if object_id('dbo.tTestIndex') is not null
    drop table dbo.tTestIndex;

create table dbo.tTestIndex (a int, b int, c int);

create index X_tTestIndex on dbo.tTestIndex (a) include (b) where c > 0;

select i.name, i.filter_definition, c.name, ic.is_included_column
from sys.indexes i
inner join sys.index_columns ic on i.object_id = ic.object_id and i.index_id = ic.index_id
left join sys.columns c on ic.object_id = c.object_id and ic.column_id = c.column_id
where i.object_id = object_id('dbo.tTestIndex');

if object_id('dbo.tTestIndex') is not null
    drop table dbo.tTestIndex;

This example gives two rows instead of three.

index_name   | filter_definition | column_name | is_included_column
-------------+-------------------+-------------+-------------------
X_tTestIndex | ([c]>(0))         | a           | 0
X_tTestIndex | ([c]>(0))         | b           | 1

Answer 1

You can use the catalog view sys.sql_expression_dependencies to find out the columns on which your filter relies:

SELECT  i.name, i.filter_definition, c.name, is_included_column = 0
FROM    sys.indexes AS i
        INNER JOIN sys.sql_expression_dependencies AS d
            ON d.referencing_id = i.[object_id]
            AND d.referencing_minor_id = i.index_id
            AND d.referencing_class_desc = 'INDEX'
        INNER JOIN sys.columns AS c
            ON c.[object_id] = d.referenced_id
            AND c.column_id = d.referenced_minor_id
WHERE   i.[object_id] = OBJECT_ID(N'dbo.tTestIndex');

You can then just UNION this to your original query to get all the columns.