Creating Customized MDX Named-Sets - ssas

Question

I have two dimensions called [Session Length] and [Date], and a measure called [Count - Logins] in my Cube. The [Session Length] dimension contains an attribute called [Session Length] whose members are integers from 0 to 240.
I like to write an MDX query which would aggregate [Count - Logins] over customized subsets of the [Session Length] dimension (i.e. I want to create a customized set based on the [Session Length] dimension and aggregate the count over individual members of this custom set). Here is the query I have come up with so far but unfortunately I have no clue how to move forward:
WITH SET [Description] AS {
[SessionLength].[Session Length].&[0], //Glimpse
[SessionLength].[Session Length].&[1]:[SessionLength].[Session Length].&[5], //Short
[SessionLength].[Session Length].&[6]:[SessionLength].[Session Length].&[30], //Medium
[SessionLength].[Session Length].&[31]:[SessionLength].[Session Length].&[90], //Long
[SessionLength].[Session Length].&[90]:[SessionLength].[Session Length].&[240]} //Extended
MEMBER [SessionLength].[Session Length].SessionDescription AS
Aggregate([Description])
SELECT
{ [Measures].[Count - Logins] }
ON COLUMNS,
NONEMPTY({[SessionLength].[Session Length].SessionDescription} * {[Date].[Date].[Date]}) ON ROWS
FROM MyCube
With the following sample result set:
Session Length | Date | Count - Logins
-------------------------------------------------
SessionDescription | 2014-02-01 | 22
SessionDescription | 2014-02-01 | 17
As you can see the count is being aggregated over the whole set and not each member individually. Here is the result I'm hoping to produce:
Session Length | Date | Count - Logins
-------------------------------------------------
Glimpse | 2014-02-01 | 3
Short | 2014-02-01 | 4
Medium | 2014-02-01 | 9
Long | 2014-02-01 | 5
Extended | 2014-02-01 | 1
Glimpse | 2014-02-02 | 2
Short | 2014-02-02 | 5
Medium | 2014-02-02 | 7
Long | 2014-02-02 | 2
Extended | 2014-02-02 | 1
Any help would be appreciated. I know this can be achieved by modifying the DSV but I don't want to alter the Cube's structure.

Answer 1

You must create separate SessionDescription members if you want to see separate entries on the rows e. g. like this:
WITH
MEMBER [SessionLength].[Session Length].Glimpse AS
Aggregate([SessionLength].[Session Length].&[0])
MEMBER [SessionLength].[Session Length].Short AS
Aggregate([SessionLength].[Session Length].&[1]:[SessionLength].[Session Length].&[5])
MEMBER [SessionLength].[Session Length].Medium AS
Aggregate([SessionLength].[Session Length].&[6]:[SessionLength].[Session Length].&[30])
MEMBER [SessionLength].[Session Length].Long AS
Aggregate([SessionLength].[Session Length].&[31]:[SessionLength].[Session Length].&[90])
MEMBER [SessionLength].[Session Length].Extended AS
Aggregate([SessionLength].[Session Length].&[90]:[SessionLength].[Session Length].&[240])
SELECT
{ [Measures].[Count - Logins] }
ON COLUMNS,
NONEMPTY({
[SessionLength].[Session Length].Glimpse,
[SessionLength].[Session Length].Short,
[SessionLength].[Session Length].Medium,
[SessionLength].[Session Length].Long,
[SessionLength].[Session Length].Extended
}
* {[Date].[Date].[Date]})
ON ROWS
FROM MyCube
By the way, I left the 90 member in both, Long and Extended as it was in your original query. If you do not want to double-count these, you should remove them from one.