Dividing tied RANKs using MDX

Question

Still getting the hang of interpreting the MDX documentation on MSDN. So for the RANK function it has the following:

If a numeric expression is specified, the Rank function determines the one-based rank for the specified tuple by evaluating the specified numeric expression against the tuple. If a numeric expression is specified, the Rank function assigns the same rank to tuples with duplicate values in the set. This assignment of the same rank to duplicate values affects the ranks of subsequent tuples in the set. For example, a set consists of the following tuples, {(a,b), (e,f), (c,d)}. The tuple (a,b) has the same value as the tuple (c,d). If the tuple (a,b) has a rank of 1, then both (a,b) and (c,d) would have a rank of 1. However, the tuple (e,f) would have a rank of 3. There could be no tuple in this set with a rank of 2. If a numeric expression is not specified, the Rank function returns the one-based ordinal position of the specified tuple. The Rank function does not order the set.

In the following script if two people are tied second for the highest salary I get the following salary ranks:

1
2
2
4

What I'd like to do is use the number of years in service to decide which of the tied people has the higher rank. Is this possible?

WITH 
    SET [OrderedPeople] AS 
        ORDER(
            NONEMPTY(
                [PeopleDimension].[PeopleHier].[NamesLevel].members,
                { //following means if one or the other is null 
                  //then the row is not excluded
                [Measures].[Salary],
                [Measures].[NumYearsService]
                }
            ),
            [Measures].[Salary]
            *
            [Measures].[NumYearsService]
            , 
            BDESC
            )
    MEMBER [Measures].[Salary_Rank] AS 
        RANK([PeopleDimension].[PeopleHier].CurrentMember,
            [OrderedPeople],
            [Measures].[Salary] //<<<how do I use numYearsService to decide ties?
            )
SELECT 
    NON EMPTY 
        { 
        [Measures].[NumYearsService],       
        [Measures].[Salary],
        [Measures].[Salary_Rank]             
        }
    ON COLUMNS,

    NON EMPTY 
        [OrderedPeople]
    ON ROWS  

FROM [ourCube]
WHERE   
    (
    {TAIL([Date].[Date - Calendar Month].[Calendar Day],7)(0):
    TAIL([Date].[Date - Calendar Month].[Calendar Day],7)(6)}
    )

Answer 1

If you have the set already ordered, you use Rank without the third argument, i. e.

RANK([PeopleDimension].[PeopleHier].CurrentMember,
     [OrderedPeople]
)

Rank returns the position that the first argument has in the set which is the second argument. The third argument is specifically used for the case when you want to have ties getting the same value. If you use the third argument, then for adjacent elements within the set, the third argument is checked, and the return value is the position of the first element within the set that has the same value for the third argument.

To order by several criteria in MDX, nest two orders within each other:

ORDER(
   ORDER(
        NONEMPTY(
            [PeopleDimension].[PeopleHier].[NamesLevel].members,
            { //following means if one or the other is null 
              //then the row is not excluded
            [Measures].[Salary],
            [Measures].[NumYearsService]
            }
        ),
        [Measures].[NumYearsService]
        , 
        BDESC
    ),
    [Measures].[Salary],
    BDESC
)

AS MDX Order is guaranteed to do a stable sort, when executing the outer sort, then the members that have the same salary do not change their relative order from the first sort, which means they keep being sorted by years in service.