MDX - calculated member with unrelated dimension - ssas

Question

I have two measures:
[Measure].[ChildCount] and [Measure].[Buyings]
and two dimensions:
[Buyers] and [Sellers].
[Measure].[ChildCount] uses [Buyers] dimension to count child organization for each of the buyer.
[Measure].[Buyings] uses [Buyers] and [Sellers] to count buying from [Seller] to [Buyer].
What I want to achieve is select all buyings for Buyers with ChildCount < 1 and Buyers with ChildCount > 0.
Currently these queries are working fine:
First one that count buying for each sender/buyer:
SELECT [Measure].[Buyings] on COLUMNS,
[Sellers].[Code].[Code] *
[Buyers].[Code].[Code] ON ROWS
FROM MyCube
And second that calculates buyings for buyers with and without childs:
WITH MEMBER [Measure].[BuyingsWithChilds]
as SUM
(
FILTER([Buyers].[Code].[Code],[Measure].[ChildCount]>0),
[Measure].[Buyings]
)
MEMBER [Measure].[BuyingsWithoutChilds]
as SUM
(
FILTER([Buyers].[Code].[Code],[Measure].[ChildCount]<1),
[Measure].[Buyings]
)
SELECT
{
[Measure].[BuyingsWithChilds],
[Measure].[BuyingsWithoutChilds]
} ON COLUMNS,
[Buyers].[Code].[Code] ON ROWS
FROM MyCube
But if I trying to combine these queries into desired one:
WITH MEMBER [Measure].[BuyingsWithChilds]
as SUM
(
FILTER([Buyers].[Code].[Code],[Measure].[ChildCount]>0),
[Measure].[Buyings]
)
MEMBER [Measure].[BuyingsWithoutChilds]
as SUM
(
FILTER([Buyers].[Code].[Code],[Measure].[ChildCount]<1),
[Measure].[Buyings]
)
SELECT
{
[Measure].[BuyingsWithChilds],
[Measure].[BuyingsWithoutChilds]
} ON COLUMNS,
[Sellers].[Code].[Code] ON ROWS
FROM MyCube
This query's execution takes forever.
Is it possible to fix or optimize this?

Answer 1

If you convert [Measure].[ChildCount]>0 and [Measure].[ChildCount]<1 to an attribute like "HasChildren", then you can avoid the Filter function which is normally slow, and which you use two times.
Then your WITH clause would be simplified to
WITH MEMBER [Measure].[BuyingsWithChilds]
as ([Buyers].[HasChildren].[Yes], [Measure].[Buyings])
MEMBER [Measure].[BuyingsWithoutChilds]
as ([Buyers].[HasChildren].[No], [Measure].[Buyings])
which should be much faster, as it uses the standard aggregation of [Measure].[Buyings].