Migrate Adventure Works Sales Cubes from SSAS MOLAP to Mondrian ROLAP

In the 2 previous blog entries about recreating the SSAS example cubes for Adventure Works sales BI on Pentaho, I focused on generating new departmental-sized ROLAP cubes through the thin client Auto Modeler tools here & here.

In this entry, I’m going to show you how you can move over to the Pentaho BA Suite quickly by getting started with your existing SSAS cubes, such as the Adventure Works sales cubes, by migrating them pretty much as-is to the Pentaho ROLAP engine called Mondrian. This way, you can use the modeling tools that you are already familiar with (i.e. BIDS) and just convert them to Mondrian. Once you are converted over to the Pentaho platform, then you can start playing around with Pentaho analytics and manage the new version of the cubes in Pentaho.

In case you didn’t already do so, make sure you go here to download the evaluation of the Pentaho Business Suite here. And here is the Codeplex link for the open source download of the Adventure Works SSAS 2012 MOLAP cubes that we’ll use for this demonstration.

Make sure you also download the SQL Server 2012 JDBC driver and the tool that I built to help you migrate your online SSAS cubes from the SQL Server Analysis Server to Mondrian XML schema output files using AMO here, called SSAS2MONDRIAN. The full source code and C# project is available on GitHub in case you want to add more to it, have a look around, etc. The tool needs more features and error catching, so please contribute your ideas back to the source project!

So basically, instead of recreating a new OLAP model in Pentaho’s Analyzer, we are going to just migrate as-is from SSAS. Instead of rewriting the details of some of the primary differences between the 2 engines that you need to be aware of, I’m going to just link you back to my last posting on this topic at KromerBigData. You’ll need to become familiar with the Mondrian schema and MDX differences because we don’t have a complete migration tool that can do it all for you. Instead, the ssas2mondrian utility will take your model outline of dimensions, measures, expressions, attributes, hierarchies and  measure groups and convert them to Mondrian descriptors and names, but leaving out decisions about conflicts and conversion gaps in the hands of the BI developer.

Ok, once you’ve loaded the AdventureWorks 2012 DW database and the MOLAP cubes from Codeplex into SQL Server, you should see them appear in your SSMS:

s0

 

Next, run the ssas2mondrian utility and redirect the output to an XML file so that we’ll be able to open the model in Pentaho Schema Workbench to make it ready for Mondrian:

mon0

You can see some of the output in that PowerShell screenshot above. I first ran the conversion utility without redirecting the output to a file, so some of the stdout is visible. I selected the server, cube, SSAS databsae and chose a new name for the resulting Mondrian schema, which is what will appear to report users when they build reports in Pentaho Analyzer.

Notice the conversion utility just using Console.WriteLine to output a Mondrian schema format. But, now I can open that schema file in Pentaho Schema Workbench (PSW) and work with it to clean things up and make it ready for Pentaho Analytics:

psw2

Make sure that you connect to the AdventureWorksDW2012 database from PSW as well under Database Connections. Remember that Mondrian is ROLAP only, so you will always send queries to the source database in Mondrian which will handle caching as well. Also take notice of the red check marks above. That means that you’ll want to open those nodes in the tree and look at the error in the bottom of the PSW screen. It is possible that some of the table names are actually named queries in the SSAS cube model, which means that those will need to become views in the source Adventure Works database to resolve the red check in PSW for Mondrian.

psw1

You can now use that ROLAP model to build Pentaho Analyzer reports and continue to maintain the models directly in Pentaho Mondrian, taking SSAS away from the solution. Or, if you like designing models in BIDS, build your cube there and then run ssas2mondrian to load the model into the Pentaho suite!

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SQL Saturday Philly: SSAS vs PowerPivot Cubes

Thank you to all of those who joined me for my Philly SQL Saturday session on building SQL Server cubes in SSAS, PowerPivot and Denali. We can use this thread for follow-up questions, discussions and links related to the topic.

First, you can download the slide deck that I used here. Second, if you want to try creating a simple baseline starting-point cube by hand using SSAS like I did in the session, I highly recommend this post here by one of my favorite, highly-recognized leaders in training Microsoft BI users, Stacia Misner. You can walk through her step-by-step instructions in a fairly short amount of time. And what I am certain that you will find is that once you’ve gone through the process of building a cube, focusing on the basics, that you will find it is not very difficult at all. After you’ve built your BI solution proof, then go back and partition the cube, adjust aggregation designs, add actions, etc. You do not need to use those cool SSAS features and most importantly, you really do not need to know MDX to get a cube started and published out to your business users.

Ok, that transitions nicely into the PowerPivot portion of the talk yesterday. To review, PowerPivot is new with SQL Server 2008 R2 and requires Excel 2010. If you wish to try out PowerPivot, all you need are the evaluation version of Excel 2010 and the PowerPivot add in, if you are not already using Excel 2010. In order to truely experience the collaboration nature of PowerPivot models, though, you will need SharePoint 2010 with SQL Server 2008 R2 to persist the in-memory cubes as they are hydrated by SharePoint.

The sample PowerPivot that I used which gives you the exact same results as the SSAS cube that I built is available as a download here. PowerPivot makes it even easier to build solutions than the cube method that I demo’d with SSAS because the cube is processed immediately in memory and is abstracted away from the model power-user. But it has many limitations in V1 that you need to make your decisions based on which Microsoft technology to use for your BI solution based on a knowledge and understanding of the impact of those limitations. For example, you cannot build explicit hierarchies in PowerPivot like you can in SSAS. The role-based security is not available in the Excel version like you have in SQL Server and the advanced capabilities outside of what I showed yesterday such as partitioning or many-to-many are not available to you.

Now, you may not need those for your solution. And as I stated several times on Saturday, I am a true believer in smaller departmental cubes as opposed to mondo big enterprise cubes. So PowerPivot will work nicely in those circumstances. Go to http://www.powerpivot.com for more examples and tutorials.

Lastly, we did not get a chance to talk about this too much, but the SQL Server Denali CTP 2, which will be made available publicly soon, will give you a first-glance chance to preview and try out the new BIDS environment which is a convergence of the PowerPivot and SSAS technologies. What this means is that if you are intimidated by MDX, you can build cubes in BIDS with DAX instead. DAX is the PowerPivot scripting language and uses Excel syntax and is much more familiar to users of Excel functions that you find in statistics, math and finance. This makes sense to me because the primary users of business intelligence are, after all, experts in math, stats & finance.

But if you are really good at making fast, efficient, complicated cubes in SSAS, you can still use the UDM model, use MDX and there will be new features add for those developers as well. But you won’t get the quick, immediate feedback on your cube through the Vertipaq technology that PowerPivot brings to the table. Instead, you have to process your cubes and worry about storage techniques as you do now. I think of this direction in SQL Server as bringing the power of the PowerPivot compression engine and in-memory analysis server to all BI developers. Very powerful stuff.

Probably the best source of information about this direction in SSAS future is directly from the SSAS product team on their blog, which you can read here.

I probably did not hit all areas in this blog post that everyone wanted as follow-up from the session. So please send in your comments and feedback and we’ll keep the thread going. My goal here is to see you all using Microsoft SQL Server in one fashion or another for your BI solutions. Let me know what I can do to help. And your feedback on the session, presentaiton, contents, etc. is also greatly appreciated.

Thanks & best! Mark