Book Image

Expert Data Modeling with Power BI - Second Edition

By : Soheil Bakhshi
4 (1)
Book Image

Expert Data Modeling with Power BI - Second Edition

4 (1)
By: Soheil Bakhshi

Overview of this book

This book is a comprehensive guide to understanding the ins and outs of data modeling and how to create full-fledged data models using Power BI confidently. In this new, fully updated edition, you'll learn how to connect data from multiple sources, understand data, define and manage relationships between data, and shape data models to gain deep and detailed insights about your organization. As you advance through the chapters, the book will demonstrate how to prepare efficient data models in the Power Query Editor and use simpler DAX code with new data modeling features. You'll explore how to use the various data modeling and navigation techniques and perform custom calculations using the modeling features with the help of real-world examples. Finally, you'll learn how to use some new and advanced modeling features to enhance your data models to carry out a wide variety of complex tasks. Additionally, you'll learn valuable best practices and explore common data modeling complications and the solutions to supercharge the process of creating a data model in Power BI and build better-performing data models. By the end of this Power BI book, you'll have gained the skills you need to structure data coming from multiple sources in different ways to create optimized data models that support high-performing reports and data analytics.
Table of Contents (22 chapters)
1
Section I: Data Modeling in Power BI
4
Section II: Data Preparation in Query Editor
10
Section III: Data Modeling
13
Section IV: Advanced Data Modeling
20
Other Books You May Enjoy
21
Index

Avoiding calculated columns when possible

Creating calculated columns is one of the most essential and powerful features of DAX. Calculated columns, as the name suggests, are computed based on a formula; therefore, the calculated column values are unavailable in the source systems or the Power Query layer. The values of the calculated columns are computed during the data refresh and then stored in memory. It is important to note that the calculated columns reside in memory unless we unload the whole data model from memory, which in Power BI means when we close the file in Power BI Desktop or switch to other content in the Power BI Service. Calculated columns, after creation, are just like any other columns, so we can use them in other calculated columns, measures, calculated tables, or for filtering the visualization layer.

A common approach of developers is to use calculated columns to divide complex equations into smaller chunks. That is why we suggest avoiding the excessive...