The terms “DirectQuery” and “Connect Live” are somehow confusing. I saw lots of people are using both terminologies as alternatives. But, the context of “DirectQuery” and “Connect Live” are very different indeed. Therefore, if use a a terminology when we’re talking about a different context then the whole situation might get quite confusing. in this post I try to explain the differences and make it more clear to prevent using a wrong terminology and make sure everyone is on the same page when we’re referring to “DirectQuery” or “Connect Live”.
When we use the “DirectQuery” terminology we are actually talking about connecting from Power BI Desktop instance to an RDBMS type of data source like SQL Server DB or Oracle DB.
There are two types of data connections when we’re connecting to RDBMS like SQL Server or Oracle DB from Power BI Desktop:
Import Data: which literally loads data into the underlying model to make it available in memory
DirectQuery: which doesn’t load data into model. Instead, it runs multiple concurrent queries on the RDBMS side (data source side) and gets the results. This is good to support real-time data processing.
Note: The same principal applies to SSAS Tabular.
On the other hand, when talk about “Connect Live”, we are referring to the data connection type from a reporting tool like Power BI Desktop OR Excel to an instance of SSAS, either SSAS Multidimensional or SSAS Tabular.
Technology is growing fast and we are enjoying it. We reshape our daily created data in a form that satisfies our needs. One of the technologies which is used more commonly these days is SQL Server Tabular Models, SSAS Tabular in short. Lots of industries decide to go with SSAS Tabular in their new projects and some defined new projects to slowly switch their existing SSAS Multidimensional to SSAS Tabular. I know, there is a big debate around SSAS Multidimensional vs. SSAS Tabular. But my aim is to prevent going through that sort of discussion. As the title implies, this post is about documentation that I believe is one of the most important parts of every project which is also sacrificed the most. In this post I explain how to document your SSAS Tabular model in Power BI Desktop and Excel. I know, there are some products you can find in the internet that can generate documentation in various formats like Word, PDF, HTML and so on. But, If you’re looking for a free and somehow more intuitive way of documenting your SSAS Tabular Models with Power BI then this article is for you. Through this article, we create a documentation tool with Power BI. I call it SSAS Tabular Model Documenter. In this method we don’t use DMVs at all. For those who are not familiar with DMVs I shortly explain what DMVs are, if you’re already familiar with DMVs you can jump this section.
You can download a copy of SSAS Tabular Model Documenter in Power BI template format (pbit) at the end of this post. It is a Christmas present for you.
What are DMVs?
Dynamic Management Views, DMVs in short, are queries that retrieve metadata information about an instance of SQL Server Analysis Services. DMVs work on both SSAS Multidimensional and SSAS Tabular server modes. DMVs can be used to monitor server operations and health. The DMV query structure is very similar to T-SQL, therefore you use “SELECT” statement followed by “$System” which is an XMLA schema rowset. The DMV queries look like below:
SELECT * FROM $System.<schemaRowset>
So you can open SQL Server Management Studio, connect to an instance of SSAS (Tabular model for the sake of this post) and run the following query to get lots of information about tables in your Tabular model:
Note:This method only works with SSAS Tabular 2016 and above.
Document SSAS Tabular without DMVs
In SSAS Tabular 2016 and above there is a tiny metadata database that can be loaded in Power BI Desktop or Excel to document the corresponding SSAS Tabular model. The database is a SQLite database. In the previous post I explained how to visualise SQLite data in Power BI. The requirements for this post are the same as the previous post, so I encourage you to check it out. Therefore, I just explain how to find the metadata file and how to build a model in Power BI Desktop. I also explain how to do the same in Excel for those of you who would like to add some annotations or comments to the outcomes.
NOTE: This method is no longer available (from 1st March 2019) as Microsoft discontinued supporting Web Designer in Azure portal. Microsoft is working on an alternative solution, but there is no timeframes or details to announce yet. Read more here. In the meantime, you still can import your Power BI Desktop Models to SSAS Tabular following the method described here.
A while ago I wrote a blog post on how to import you currently existing Power BI Desktop models to SSAS Tabular 2016. However, the method I explained is NOT supported by official Microsoft BI tools like SSDT, so you may consider it as a WORKAROUND only until Microsoft supports imploring Power BI models in SSDT. In this post, I show you how to import Power BI Desktop Model to SSAS Tabular 2017 using Azure Analysis Services. It is easy and hassle free.
Power BI Desktop: Make sure you have the latest version (Current Version: 2.52.4921.581 64-bit (November 2017))
Azure Subscription: You need to install an instance of Azure Analysis Services. Don’t worry about the costs, you can create an Azure free account with $200 credit for 30 days. Learn more here.
In this post I do NOT explain how to install Azure Analysis Services
This method works only for SQL Server Analysis Services 2017 Tabular
How it works
As mentioned earlier it is really easy in compare with other methods I explained in my previous post. Azure Analysis Services is capable of importing Power BI Desktop files creating a Tabular model version of your Power BI model in the cloud. Then you can simply download Visual Studio project file and redeploy it in your on-premises instance of SSAS Tabular 2017. Let’s go through the steps…
Open Power BI Desktop
Import data from WorldWideImportersDW from any desired combination of fact tables and dimensions. I imported
A while ago I was working on a Power BI project which the customer wanted to define a new table directly in the model. The easiest way to achieve this in Power BI Desktop is to “Enter Data” which creates a new table by typing or pasting in new contents. I was thinking of that project the other day and thought, hey, how we can do the same in SSAS Tabular when there is no Power Query (M) language available in SSAS Tabular 2016. The good news is that Power Query will be available in the next version of SSAS Tabular in SQL Server vNext. But, until then a workaround would be entering data to a CSV file then load it to the model. Another way is to implement custom tables in DAX in SQL Server 2016 Tabular models using Table and Row Constructors. In this post I show you a way of creating custom table in SSAS Tabular using table constructors in DAX. You can do the same in Power BI as the same principle applies. Therefore, in case you’d prefer not to use “Enter Data” feature which effectively uses Power Query to create a new table in Power BI Desktop, then you can use DAX to do the same.
If don’t already have SQL Server 2016 it’s probably time to download and install it. I use AdventureWorksDW as sample database in this article.
You are involved with an SSAS Tabular project and the customer asked for a report in Power BI with dynamic Card so that the values shown in the Card visual should dynamically change based on selected measure from a slicer. You have several different measures in the model and the customer wants to show some of them dynamically in only one Card visual. Consider you have the following measures to be shown in the Card:
Total Internet Sales
Internet Sales in 2014
Total Number of Internet Sales Transactions
You have to create a logic so that the users can selected any of the above measures to show in a single Card visual.
How it works
After you meet the requirements, you’re good to start implementing the above scenario in SQL Server Data Tool (SSDT). Creating a calculated table in SSAS Tabular 2016 is fairly easy. All we need to do is to create a custom table with two columns. One column stores friendly names for measures and the other one holds DAX expressions for the measures. As you might have noticed, I’m talking about creating a custom table in DAX and populating it with values. Continue reading to see how. What we are going to do is to create a calculated table using table constructors in DAX. Table and Row Constructors weren’t available in previous versions of DAX in SSAS Tabular. They are very similar to Lists or a list of Tuples just like what we have in MDX.
You’ve changed something in your Tabular model and you’re facing an ugly “Error: Object reference not set to an instance of an object.” message, don’t rush. Just go to the table you’ve made some changes and click on “Partitions” button.