Filtered indexes - throws

[JaBistDuNarrisch]

If you call this it throws. If not all providers accepts it we could distinguish and throw for the used provider. SQL Server supports adding filters for columns that are not part of the keycolumns array.

    Database.AddIndex("Blaaaa", new Index
    {
        Name = "UX_ddddd",
        Unique = true,
        Clustered = false,
        KeyColumns = ["IpaUserIdentifier"],
        FilterItems =
        [
            new FilterItem
            {
                ColumnName = "IpaUserIdentifier",
                Filter = FilterType.NotEqualTo,
                Value = null
            },
            new FilterItem
            {
                ColumnName = "Archive",
                Filter = FilterType.EqualTo,
                Value = 0
            }
        ]
    });