Execution order of crossjoined hierarchies

问题

If I create a set of tuples via the following crossjoin which hierarchy is joined to which first?

hierA * hierB * hierC

If I know that the count of non empty members in A and B are significantly less than the count of members in C then should this influence the order?

回答1:

It depends on the execution system used, i.e. how crossjoining on axis is optimized by compiler.

Anyway, you will get real boost only if you first reduce cube size with subselect - it will prevent crossjoining non-matching points:

select
 { [Measures].[X] } on 0,
 { [DimA].[A] * [DimB].[B] } on 1
From ( 
             select { [DimB].[B].members}   on 0 
             from CubeA
           )

来源：https://stackoverflow.com/questions/28098346/execution-order-of-crossjoined-hierarchies