Is the Tuple in MDX an implicit crossjoin?

Question

Are the two statements equivalent?

Tuple:

  SELECT  {[Measures].[Volume]}  ON COLUMNS, 
  ([Product].[Product Id].[Product Id].AllMembers
  ,[Time].[Time].[Year].AllMembers)  ON ROWS 
   FROM [My Cube]

Versus explicit crossjoin:

SELECT  {[Measures].[Volume]}  ON COLUMNS, 
  [Product].[Product Id].[Product Id].AllMembers
       * [Time].[Time].[Year].AllMembers  ON ROWS 
       FROM [My Cube]

They seem to return the same result, but it seemed from the reading I have done that they shouldn't (at least not always).

Answer 1

What you have in your first query is not a tuple. Tuples are made up of a collection of one or more members

eg. (member1, member2, ...)

Where as what you have is (set1, set2 ...). which I think of as a subcube as this is what is use when defining subcubes for scope statements. And a subcube is essentially an implied crossjoin, so your two queries should return the same result.