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Category: Power BI

Delta Live Tables and Power BI Data Modeling

Published 2022-06-21 by Kevin Feasel

Tahir Fayyaz goes from Delta Lake to Power BI:

To get the optimal performance from Power BI it is recommended to use a star schema data model and to make use of user-defined aggregated tables. However, as you build out your facts, dimensions, and aggregation tables and views in Delta Lake, ready to be used by the Power BI data model, it can become complicated to manage all the pipelines, dependencies, and data quality as you need to consider the following:

– How to easily develop and manage the data model’s transformation code.

– How to run and scale data pipelines for the model as data volumes grow.

– How to keep all the Delta Lake tables updated as new data arrives.

– How to view the lineage for all tables as the model gets more complex.

– How to actively stop data quality issues that result in incorrect reports.

Read on for recommendations, a couple architectural diagrams, and some sample code.

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Power BI Field Parameters and Type 2 SCDs with Bonus Fields

Published 2022-06-20 by Kevin Feasel

Koen Verbeeck extends the type 2 slowly changing dimension:

Power BI field parameters are a new feature in Power BI Desktop, and it’s one of the best of the past months. In short, Power BI field parameters allow you to easily switch between dimensions attributes or measures in a filter. Previously, you had to do all sorts of DAX wizardry to make this happen, but now it’s just a couple of clicks.

The goal of this blog post is not to tell you exactly how they work, but rather showcase an interesting use case. You can find more info about Power BI field parameters in the official blog post, but also here, here and here. The use case I’m talking about is slowly changing dimensions of Type 2, you know, the one where we insert a record for every change. Often, I also include an extra column for each column of which we’re tracking history: the “current value column”. For example, if we keep history of the department for an employee, I have a column “CurrentDepartment”. If a type 2 change occurs, the values of this columns are updated to the last known value for this dimension member. This allows to answer different types of questions, because sometimes users are interested in the historical values, but sometimes they just want to know the current value.

Read on for the use case as well as how you might combine field parameters with the idea of current values on type-2 slowly changing dimensions.

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Creating Calculation Groups in Power BI Desktop via Powershell

Published 2022-06-20 by Kevin Feasel

Phil Seamark helps those who are stuck lacking tools:

I recently shared on Twitter a 7-module learning path on MS Learn that teaches all you need to know about calculation groups in Power BI. This learning path is an excellent course, and I highly recommend it. However, as part of this exchange, I received a reply from someone lamenting that calculation groups are unusable in organisations that will not allow non-Microsoft applications. Power BI Desktop does not currently have UX enabling you to create/manage calculation groups in a Power BI Model, so the most common method today is to use 3rd party tools such as Tabular Editor.

This exchange is not the first time I have heard this feedback, so I decided to share a technique showing how you can use Microsoft tools. The approach used in this article uses PowerShell but can quickly get translated to VS Code or other scripting environments.

Click through if you’re in that unfortunate situation.

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Building a Rank in Power Query

Published 2022-06-20 by Kevin Feasel

Reza Rad ranks things:

Although, calculating rank dynamically is often useful, It is not rare to need to do ranking on a pre-calculated basis. Let’s say, for example, you want to create an aggregated table by customers and year. and you want to rank customers based on their sales amount in that table. the period and other factors are remaining static. This pre-calculated aggregated table can speed up the performance of your report significantly in the future. In a case like this, the rank calculation can be done as a pre-calculation. And when you do this as a pre-calculation, Power Query is a useful option. Because then you can do that even in a Dataflow, and the result can be used in multiple Power BI datasets.

Click through to see how you can do it, as well as what Power Query calls its equivalents to ROW_NUMBER(), RANK(), and DENSE_RANK().

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Extracting Data from DAX Measures into CSV

Published 2022-06-17 by Kevin Feasel

Gilbert Quevauvilliers builds a process:

In this blog post I am going to demonstrate how to use the new Power Automate Flow to extract data from a DAX measure into a SharePoint CSV file.

I got this idea after reading the blog post from the Microsoft Power BI Team: Unlocking new self-service BI scenarios with ExecuteQueries support in Power Automate | Microsoft Power BI Blog | Microsoft Power BI

The great news is that this works on Power BI Pro, Premium Per User and Premium.

Read on to see how.

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Using SELECTEDVALUE with Field Parameters

Published 2022-06-13 by Kevin Feasel

Marco Russo diagnoses an error:

If you try to use SELECTEDVALUE on the visible column of the table generated by the Fields Parameters feature in Power BI, you get the following error:

Calculation error in measure ‘Sales'[Selection]: Column [Parameter] is part of composite key, but not all columns of the composite key are included in the expression or its dependent expression.

Read on to understand what causes this error and what you can do to resolve it.

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Implementing a Power BI Composite Model

Published 2022-06-09 by Kevin Feasel

Marc Lelijveld walks us through an implementation of the Power BI composite model:

Have you been working with Composite Models in Power BI? Did you run into challenges while you did? Then this blog is for you! In this blog I will further elaborate on what the composite models (including DirectQuery for Power BI datasets) are and everything that comes into play when you start implementing them.

During this blog I will introduce you to topics like source groups, storage modes and relationship evaluation. All different topics that come into play when you start building composite models.

If composite models sound interesting, be sure to check this out.

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Reviewing Power BI Field Parameters

Published 2022-06-08 by Kevin Feasel

Teo Lachev is pleased:

Coming back from a long vacation and I almost missed this new Power BI killer feature: Field Parameters! Not to be confused with Dynamic M Query Parameters that I ranted about here, field parameters solve a long-standing limitation of Power BI that prevents you to bind dynamically dimension members to a visual. Dynamic binding wasn’t issue with measures because they are dynamic and can evaluate runtime conditions, such as slicer selection. But dimensions were a different story. Once you have bound them to a category bucket in a visual, you couldn’t change them on the fly.

Read on for more information on a common scenario in which field parameters can be quite helpful.

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KEEPFILTERS in DAX

Published 2022-06-07 by Kevin Feasel

Marco Russo and Alberto Ferrari explain how the KEEPFILTERS function works:

KEEPFILTERS is a CALCULATE modifier used to change the way CALCULATE merges new filters with the outer filter context. Indeed, the default behavior of CALCULATE is to override existing filters. By using KEEPFILTERS you ask CALCULATE to add the new filter to the outer filter context, instead of overriding the outer filter.

Read on for the explanation and a demo.

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