MDX to count common members - EXISTS alternative - ssas

Question

Let me describe the issue giving example from [Adventure Works] cube.
Following MDX returns count of 17473
SELECT NON EMPTY { [Measures].[Internet Order Count] } ON COLUMNS,
[Internet Sales Order Details].[Sales Order Number] on ROWS
FROM [Adventure Works])
WHERE ( [Sales Reason].[Sales Reason].&[1] -- price
and following returns count of 3515
SELECT NON EMPTY { [Measures].[Internet Order Count] } ON COLUMNS ,
[Internet Sales Order Details].[Sales Order Number] on ROWS
FROM [Adventure Works]
WHERE ( [Sales Reason].[Sales Reason].&[2]) -- on promotion
I would like to count [Sales Order Number] which are common in [Sales Reason].&1 and [Sales Reason].&[2]
SQL equivalent would be:
select count(distinct f.SalesOrderNumber)
from FactInternetSales f
join FactInternetSalesReason fs
on f.SalesOrderNumber = fs.SalesOrderNumber and f.SalesOrderLineNumber = fs.SalesOrderLineNumber
where fs.SalesReasonKey = 1 and fs.SalesOrderNumber in
(select SalesOrderNumber from FactInternetSalesReason fs1 where fs1.SalesReasonKey = 2)
-- sales reason 1 = 17473
-- sales reason 2 = 3515
-- common 1689
I got common count using following mdx:
WITH MEMBER [Measures].[common] AS count
( exists ( exists ([Internet Sales Order Details].[Sales Order Number].[Sales Order Number].Members,
[Sales Reason].[Sales Reason].&[1],"Internet Orders"
),
[Sales Reason].[Sales Reason].&[2],"Internet Orders"
)
)
SELECT NON EMPTY [Measures].[common] ON COLUMNS
FROM [Adventure Works]
-- 1689
But use of EXISTS is rather slow for my requirement. Please suggest an alternative.
Also please see related thread here
Thank you

Answer 1

Please try adding both reasons to the WHERE clause as a single set:
SELECT
NON EMPTY
{[Measures].[Internet Order Count]} ON COLUMNS
,[Internet Sales Order Details].[Sales Order Number] ON ROWS
FROM [Adventure Works]
WHERE
{
[Sales Reason].[Sales Reason].&[2]
,[Sales Reason].[Sales Reason].&[1]
};
Here is an alternative that runs faster, only looks at the common orders, and does not use the EXISTS function:
WITH
SET [AllOrders] AS
[Internet Sales Order Details].[Sales Order Number].[Sales Order Number].MEMBERS
SET [OrdersIntersection] AS
Intersect
(
NonEmpty
(
[AllOrders]
,{
(
[Sales Reason].[Sales Reason].&[1]
,[Measures].[Internet Order Count]
)
}
)
,NonEmpty
(
[AllOrders]
,{
(
[Sales Reason].[Sales Reason].&[2]
,[Measures].[Internet Order Count]
)
}
)
)
MEMBER [Measures].[commonCount] AS
[OrdersIntersection].Count
SELECT
//NON EMPTY //<<not needed
[Measures].[commonCount] ON COLUMNS
FROM [Adventure Works];