Category: SQL Server Analysis Services – SSAS

BISM Tabular, Business Intelligence - BI, Power BI, Power BI Desktop, Power Query, SQL Server Analysis Services - SSAS

DAX Measure Dependencies in SSAS Tabular and Power BI

DAX measures are the heart of every SSAS Tabular model, Power BI and Power Pivot solution. You write lots of DAX measures and you potentially reference some of them in other measures. So the number of DAX measures you write and reference them via other measures grow very quickly. Especially in complex solutions you may have hundreds of DAX measures. While your solution works perfectly, to make a minor change or adding a new measure to the solution or fixing a problem in your existing measures can be such a pain in the neck. In this post I’m going to take a step further and show you a simple way to get the whole data model dependencies then visualise the dependencies in Power BI. You can find the download link at the end of this post.

A simple search in Google brings you a bunch of useful articles talking about the subject. Some of the bests, in my mind, are as below:

In this post I use a DMV that gives us everything we want. ( Chris Webb already discussed the DMV here: Document Dependencies Between DAX Calculations). Running the DMV we can see what measures are references by other measures, what columns are referenced in the calculated columns and much more.

This is a very useful DMV that helps us getting a better understanding of the model we’re working on. We can also use this method for documentation.

How It Works

This method is fairly simple, you just need to run the following DMV on top of your SSAS Tabular model or your Power BI Desktop file and Import the results in Power BI.

SELECT * FROM $System.DISCOVER_CALC_DEPENDENCY

For Power BI you’ll need to find the local port number then you’re good to go. The only part that might not look very straightforward at first, would be finding the database in Power BI Desktop model.

An easy way, after you find the local port number of an opened Power BI Desktop file, is to find the database name from SQL Server Management Studio (SSMS) when connecting to the Power BI Desktop model:

  • Open SSMS
  • Select “Analysis Services” as “Server Type”
  • Type in “localhost:PORT_NUMBER” as “Server Name” then click “Connect”

Connect to Power BI Desktop Model from SSMS

Continue reading “DAX Measure Dependencies in SSAS Tabular and Power BI” →

BISM Tabular, Business Intelligence - BI, Power BI, Power BI Desktop

Demystifying “DirectQuery” and “Connect Live”

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.

DirectQuery/Data Import Mode in Power BI Desktop

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.

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Azure, Azure Analysis Services, BISM Tabular, On-premises Data Gateway Enterprise Mode

On-premises Data Gateway for Azure Analysis Services

On-prem Data Gateway for Azure AS, How it works DemoFrom April 2017 onward we can use On-premises Data Gateway for Azure Analysis Services. This means  you can connect your Tabular Models hosted in Azure Analysis Services to your on-premises data sources through On-premises Data Gateway. In this post you learn how to setup and configure the On-premises Data Gateway as well as how to configure Azure Analysis Services to connect to the on-premises database(s) via the gateway.

Requirements/Assumptions

  • You have an Azure subscription
  • You already have an up and running instance of Azure Analysis Services (AAS)
  • You already installed and configured the latest version of On-premises Data Gateway
  • Your instance of Azure Analysis Services, your instance of Power BI Service and your On-premises Data Gateway are all in the same “Region” (Check Prerequisites section below for more details)
  • This post covers the most common scenario which doesn’t involve Kerberos, Proxy Server, OKTA etc…

Reading: If you are not that familiar with On-premises Data Gateway then I encourage you to read this and for more in-depth read this article. You may also watch this video from Adam Saxton discussing On-premises Data Gateway.

Prerequisites

As stated in the “Requirements” section, it is important to check if your instances of Azure Analysis Services, Power BI Service and On-premises Data Gateway located in the same “Region”.

The reasons behind that are:

  • Your On-premises Data Gateway MUST be installed in the same Region as your Power BI Service sits in. Otherwise your Power BI cannot see the gateway, therefore, you’re unable to schedule automatic data refresh in Power BI Service
  • To get the best performance and more reliability, you have to create On-premises Data Gateway Resource in Azure side in the same region as your Azure Analysis Services lives in

But, in some cases people created their Power BI account a long time ago and perhaps they didn’t set the right region for their Power BI Service to sit in. Now, they need to create an instance of Azure Analysis Services, but, due to their organisation privacy and security, they don’t want to (or perhaps not allowed to) create the instance of Azure Analysis Services in the region that their Power BI tenant sits in. So they would prefer to create the Azure Analysis Services in another region. In that case, it is recommended to install a new instance of On-premises Data Gateway in a separate server and change the “Gateway Region” during the installation.

To check the “Region” of your instances follow the steps below:

Power BI Service Region:

  • Login to your Power BI Service
  • Click the question mark on top right side of the page
  • Click “About Power BI”

Continue reading “On-premises Data Gateway for Azure Analysis Services” →

BISM Tabular, DAX, Power BI, Power BI Desktop, Power Query, SQL Server Analysis Services - SSAS, SQLite

SSAS Tabular Model Documenter with Power BI without DMVs

SSAS Tabular Documenter with Power BITechnology 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:

select * from $SYSTEM.TMSCHEMA_TABLES

Running DMVs in SSMSRead more about DMVs here.

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.

Continue reading “SSAS Tabular Model Documenter with Power BI without DMVs” →