DAX Editor Adds Support for Tabular Default Members

In my previous blog, I announced a few new features for DAX Editor for Tabular. Today, I checked in another change that adds support for default members. Currently, Tabular doesn’t have UI for defining default members. However, you can define default members in the MdxScript section of the BIM file using MDX syntax just like you can do so in Multidimensional.

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The only issue is that if you make a change to any Tabular calculated measure in the designer, SSDT will regenerate the script and your manual changes will be lost. That is unless you use DAX Editor as its support for default members keeps them in the script. As a disclaimer, I took the backdoor approach for defining the default member syntax. The right approach would be to build upon the wonderful work of Nickolai Medveditskov and check the default member syntax so DAX Editor catches syntax errors as you type and when you attempt to save the measures. But that would have required a lot of work with Managed Babel. Moreover, the next version of SQL Server might support default members natively so all this work could be wasted.

So, I’ve decided to implement default members by allowing you to define a custom MDX script section in the *.dax file that is carried verbatim to the Tabular model without any syntax checking or changes. Of course, if you make an error, e.g. reference a column that doesn’t exist or use wrong syntax, you’ll find this pretty quickly when you attempt to open the *.bim file. To fix this, check your syntax in DAX Editor and save the changes to the *.bim file again. Or, open the *.bim file source and remove the custom MDX script which you’ll find inside the <MdxScript> element.

The syntax for default members is simple:

  1. In the DAX file, add the following section at the top of the file. It actually can appear anywhere but I’d typically put it on top when working with cube scripts.

    — MDX SCRIPT —

    ALTER Cube CurrentCube Update Dimension [Product].[Is Finished Goods], Default_Member = [Product].[Is Finished Goods].&[TRUE];

    ALTER Cube CurrentCube Update Dimension [Currency].[Currency Code], Default_Member = [Currency].[Currency Code].&[USD];

    — MDX SCRIPT —

IMPORTANT Notice that the script block has to be enclosed with “— MDX SCRIPT –” comments exactly as they appear in the example. DAX Editor looks for this pair of comments to identify the custom script block.

  1. Inside the comments, enter ALTER CUBE statements to set the default members using MDX syntax as you would do it in Multidimensional cube scripts. Notice the MDX UniqueMember syntax for the Default_Member property. In this case, I set two default members. Specifically, the Is Finished Goods column in the Product table is set to the TRUE member () and the Currency Code column in the Currency table is set to USD.
  2. Click the “Save Measures to BIM File” button in the DAX Editor Toolbar to apply the DAX Editor changes to the *.bim file as usual.

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I haven’t tested it yet but you should be able to add other MDX script commands to the DAX Editor script, such as KPI definitions, which DAX Editor doesn’t currently support.

Enjoy!

DAX Editor New Features

As it stands, Tabular (versions 2012 and 2014) doesn’t have the equivalent of a cube script. Instead, the developer has to use the Measures grid to maintain DAX calculated measures. This is OK with a few measures but as the number of measures grows, the development experience suffers because it’s getting harder to locate these measures. Besides, every time you make a change, you need to wait for the Tabular environment to refresh which gets annoying quickly. However, you can use the DAX Editor community sample to simulate a Tabular script. DAX Editor allows you to extract all measures from a Tabular model and maintain them outside the model in a DAX file. DAX Editor was initially developed by Microsoft (kudos to Nickolai Medveditskov).

Marco Russo and I teamed up to add some new features to DAX Editor as follows:

  1. Support of Visible and Description properties. Although only Power View supports field descriptions (Excel doesn’t), entering user-friendly descriptions allows you to implement self-documented models. For example, you can get a list of all measures and descriptions from the $SYSTEM.MDSCHEMA_MEASURES DMVs. The following example shows you how to use Visible and Description properties:

    CREATE MEASURE ‘Internet Sales'[Internet Distinct Count Sales Order]=DISTINCTCOUNT([Sales Order Number]) CALCULATION PROPERTY NumberWhole Visible=False ThousandSeparator=True Format=’#,0′ Description=’Returns unique number of sales orders’;

 Notice that even if don’t want to overwrite the measure format, you still have to specify the default General format so that DAX Editor can parse the syntax:

CREATE MEASURE ‘Internet Sales'[Internet Distinct Count Sales Order]=DISTINCTCOUNT([Sales Order Number]) CALCULATION PROPERTY General Visible=False Description=’Returns unique number of sales orders’;  

     2.   Support of Visual Studio 2013 although it requires a workaround to fix the bindings for the Microsoft.VisualStudio.Package.LanguageService.* dlls. Specifically, you need to modify the VS 2013 devenv.config (C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe.config) as follows:

<dependentAssembly>

       <assemblyIdentity name=Microsoft.VisualStudio.Package.LanguageService.11.0 publicKeyToken=b03f5f7f11d50a3a culture=neutral/>

       <bindingRedirect oldVersion=2.0.0.0-11.0.0.0 newVersion=11.0.0.0/>

</dependentAssembly>

<dependentAssembly>

       <assemblyIdentity name=Microsoft.VisualStudio.Package.LanguageService.10.0 publicKeyToken=b03f5f7f11d50a3a culture=neutral/>

       <bindingRedirect oldVersion=2.0.0.0-11.0.0.0 newVersion=10.0.0.0/>

</dependentAssembly>

We still have some outstanding work to test and make the binaries available for download and on Visual Studio Extension Gallery. Meanwhile, you can get the latest source (build 42258 as of now) and build it as follows:

  1. Install Visual Studio 2010 (C#) and the Visual Studio 2010 SDK. You must use Visual Studio 2010 to open the DAX Editor source as Visual Studio 2012 and above will upgrade the project.
  2. Open the DAX Editor source in Visual Studio 2010 and build the project.
  3. If you use Visual Studio 2013, fix the bindings as I explained above.
  4. Double-click the DaxEditor.vsix in the bin/debug folder and associated with the desired versions of Visual Studio you have on your machine.

The next thing on my list is to add support for Tabular default members and KPIs. The usual disclaimer applies that the sample is not supported and its features might not work with future editions of SQL Server. Other than this, enjoy it and I hope you find it useful as I do with my current projects.

 

Power BI vNext SSAS Connector and Security Reloaded

To follow up on my previous post on the same subject, a customer was eager to jump on the Power BI->On Prem SSAS bandwagon and try the simplified security model. But “omne initium difficile est” (every beginning is difficult). Their SSAS server was installed on a domain acme.com while their e-mail addresses were using a different scheme, e.g. user@contoso.com, although both server and accounts were under the same acme domain. As we’ve quickly found out, Active Directory had an issue with this setup which manifested with the following error in the SQL Server Profiler connected to SSAS.

“The following system error occurred: The name provided is not a properly formed account name.”

If you see this error, follow these steps to confirm the issue:

  1. Remote in to your SSAS server.
  2. Open Command Prompt and enter:
    Whoami/upn
  3. If you see that your login domain name is different that the e-mail you use to sign up to Power BI, you’ll have the same issue. For example, your e-mail address might be user@contoso.com while whoami might show user@acme.com.

The workaround is to bridge the two identity schemes by adding an alternative UPN suffix in Active Directory Users and Trusts, as Greg Galloway explained here. This of course will require help from your AD administrator (one of the most important persons to befriend on your BI quest) so some coercing is to be expected.

Thanks to Jen Underwood, Will Thompson, Mini Nair and Giri Nair from Microsoft who helped us troubleshoot the issue.

Projecting a Scalar Value with DAX EVALUATE Queries

When you work on more complicated DAX measures, you should get out of the Power Pivot or BISM design environment and use the excellent DAXStudio (or SSMS) with the EVALUATE query syntax. But then eventually the measure would return a scalar value while EVALUATE requires a table. You can use the DAX ROW function to create a single-row, single-column table, and then show the result using EVALUATE.

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Power BI vNext SSAS Connector and Security

As you’ve probably heard, Power BI vNext will allow you to keep your data on premises in SSAS MD and Tabular data models while your reports in the cloud can connect to these data models on premises. Currently, the Analysis Services connector support only Tabular models while plans for MD have been announced as well. Currently, SSAS understand Windows security only and you might wonder what needs to be put in place for security to work.

Interestingly, if your users have used their work e-mail addresses to sign up for Power BI and your company is using Active Directory, you don’t need do synchronize your AD with Azure using DirSync. That’s because Power BI will pass the user identity on the connection string using the EffectiveUserName property. Consequently, connectivity and data security will work as usual. On the other hand, if users used an .onmicrosoft.com e-mail address, DirSync is required. Microsoft explains this in more details in the “Why you might need use DirSync to connect to an on-premises Analysis Services Server” document.

While this definitely simplifies the effort to get Windows security working, it doesn’t help if custom security, such as Forms Authentication, is required, such as to integrate Power BI with custom applications. Embedding Power BI reports on custom applications and supporting custom security are on the Power BI top wish list and I hope Microsoft will support this scenario soon as well.