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SAP, MDX and the right language for BI

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Via Amyn Rajan’s blog I’ve learnt about a forthcoming MDX book, “MDX Reporting and Analytics with SAP”, and also seen some encouraging news on the SAP Business Objects Roadmap where MDX will be a core element. As an MDX guy – and more specifically as someone who make his living from MDX – I’m pleased to see this level of support for MDX from someone other than Microsoft and Mondrian. Even if I never do any consultancy work on SAP MDX (although I’d be interested since I hear rates are much higher than for Microsoft work!) I have a vested interest in the popularity of the MDX language in general. Yes, it’s difficult to learn and sometimes inconsistent, but I am 100% convinced it’s the best language for multidimensional queries and calculations and much better than SQL.

To a certain extent we’re all guilty of promoting the technology we know and love as the way of solving all problems; and whenever we come across a problem our technology can’t solve easily, the temptation is to extend it and improve it so that it can solve the problem. However in the case of SQL and BI there comes a point where no amount of extensions and improvements can make it do what you want it to do efficiently and easily. To paraphrase Dr Johnson, a complex BI-type calculation done in SQL is like a dog walking on its hind legs. It is not done well, but you are surprised to find it done at all. There are plenty of vendors and bloggers who would disagree with me on this though, I know.

One good example of where MDX scores over SQL is that it inherently knows about order on hierarchies: for example it knows (because you told it when you built your dimension) that Monday comes after Sunday, that 2009 comes after 2008, that June comes after May. This makes doing time-based calculations very easy, and time based calculations are part of just about every BI solution. The ability to order a set and then work with it is also important for other types of problem, such as the grouped string concatenation puzzle that Adam Machanic blogged about recently. In MDX, to solve this problem and get an ordered list of product names, you just need to order a set and then use the Generate function, for example:

Generate(
Order(
  NonEmpty(
   [Product].[Product].[Product].MEMBERS
  ,[Measures].[Internet Sales Amount])
,[Product].[Product].CurrentMember.Name,BASC)
,[Product].[Product].CurrentMember.Name,",")

But I’m getting carried away again. Arguing the merits of a language is all very well, but it’s commercial support that is what actually matters of course. And to get back to my original point that’s why I’m pleased to see that SAP seems to agree with me that MDX is a good thing.

Written by Chris Webb

June 26, 2009 at 11:46 am

Posted in MDX

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