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chubbsondubs (2) [Avatar] Offline
"Learning MDX
Multi-Dimensional Expressions are a large topic. We cover some of the basics of MDX and the expressions you will likely find useful, but covering all of MDX is beyond the scope of this book. See appendix E for more on MDX."

I was disappointed to read that this book wouldn't cover MDX at any real depth. Creating schemas isn't particularly hard, but working with MDX, beyond the simplistic roll ups and simple calculations, is darn near impossible to find any help on. I've spent months trying to solve problems using MDX, and I can't make it work. Now I could be just dense, but given I've been doing software development for over 15 years on a variety of platforms I gotta think I've got the basic raw intelligence to understand it. But I find MDX more impenetrable than anything I've ever done before.

MDX is supposed to be an open standard, but I find Mondrian doesn't completely match the same spec as Microsoft implements. Using the Microsoft Community to try and learn MDX is frustrating because it doesn't take long to find differences in Mondrian and MS. And when there are differences we don't have any documentation on how to translate it into Mondrian MDX. So I'd like to see a full treatment of MDX for Mondrian and some recipes of commonly solved problems with MDX. The MDX API reference is poorly documented for Mondrian. Is Appendix E only going to be a regurgitation of the same API docs already out there?
julian.hyde (7) [Avatar] Offline
Re: Mondrian and MDX
MDX is such a rich language that it's hard to do it justice in anything shorter than a (fairly long) book. MDX does crop up throughout Mondrian, so there will be fair amount of it in the book.

We will be sure to document the differences between Mondrian's MDX dialect and "standard" Microsoft MDX, as you suggest. (As the designer of Mondrian, it has always been my goal to minimize those differences, but they definitely exist. I think you will find that Mondrian version 4 closes the gap and makes Mondrian more compatible with recent versions of SQL Server.) Since we can't be a comprehensive guide to MDX programming, once we have set out those differences, it should be somewhat easier to use other MDX resources out there.

We appreciate your feedback. Although we won't be able to cover MDX in the depth you'd like, I am sure that you will find that this is a useful book that ties together all of the aspects of Mondrian's functionality much better than any other documentation currently out there.

chubbsondubs (2) [Avatar] Offline
Re: Mondrian and MDX

Thanks for your feedback, and thanks for such a great software product. Well after I reread my "question" I realized I didn't really specify what I was intending to ask. Given the fact that MDX won't be the focus of this book, and as you say it's a deep topic is there any interest in doing a book focused on MDX in Mondian?

julian.hyde (7) [Avatar] Offline
Re: Mondrian and MDX
Depends how well this one sells. smilie
fallingdown (1) [Avatar] Offline
Re: Mondrian and MDX
I'm really interested in learning more about MDX. I noticed that the examples in the book seem to show an interactive console (similar to sqlplus). Can you tell me what you are using? Is it CmdRunner? Do you have a preferred tool/utility you use to experiment with MDX queries (other than pentaho)?

Thanks! Really looking forward to the release of the book.
julian.hyde (7) [Avatar] Offline
Re: Mondrian and MDX
The examples are generated by a tool I wrote that is similar to CmdRunner. (Not currently released -- sorry!) I used it because the output format is a bit more legible and concise than CmdRunner's output.

If you are connecting via XMLA, you could use Roland Bouman's xmla4js tool, It has a nice web interface for running MDX queries, and works against any XMLA data source, not just Mondrian.

fabiodesalles (1) [Avatar] Offline
Re: Mondrian and MDX
Julian, are able to recomend an MDX forum? I have read books on it and now I am on that trial-and-error process, strugling to get a hold on MDX. I feel this forum here is not the place - but I won't mind asking MDX questions here if there is no problem with it...