Book Image

Expert Data Modeling with Power BI

By : Soheil Bakhshi
Book Image

Expert Data Modeling with Power BI

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 data models using Power BI confidently. 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. In this book, you'll explore how to use data modeling and navigation techniques to define relationships and create a data model before defining new metrics and performing custom calculations using modeling features. As you advance through the chapters, the book will demonstrate how to create full-fledged data models, enabling you to create efficient data models and simpler DAX code with new data modeling features. With the help of examples, you'll discover how you can solve business challenges by building optimal data models and changing your existing data models to meet evolving business requirements. 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. 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 reporting and data analytics.
Table of Contents (18 chapters)
Section 1: Data Modeling in Power BI
Section 2: Data Preparation in Query Editor
Section 3: Data Modeling
Section 4: Advanced Data Modeling

Avoiding calculated columns when possible

The ability to create calculated columns is one of the most essential and powerful features in DAX. Calculated columns, as the name suggests, are computed based on a formula; therefore, the calculated column values are not available either in the source systems or in 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 contents 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, calculate tables, or for filtering the visualization layer. A common approach between developers is to use calculated columns to divide complex equations into smaller chunks. That is precisely the...