Book Image

Hands-On Business Intelligence with DAX

By : Ian Horne
Book Image

Hands-On Business Intelligence with DAX

By: Ian Horne

Overview of this book

Data Analysis Expressions (DAX) is known for its ability to increase efficiency by extracting new information from data that is already present in your model. With this book, you’ll learn to use DAX’s functionality and flexibility in the BI and data analytics domains. You’ll start by learning the basics of DAX, along with understanding the importance of good data models, and how to write efficient DAX formulas by using variables and formatting styles. You’ll then explore how DAX queries work with the help of examples. The book will guide you through optimizing the BI workflow by writing powerful DAX queries. Next, you’ll learn to manipulate and load data of varying complexity within Microsoft products such as Power BI, SQL Server, and Excel Power Pivot. You’ll then discover how to build and extend your data models to gain additional insights, before covering progressive DAX syntax and functions to understand complex relationships in DAX. Later, you’ll focus on important DAX functions, specifically those related to tables, date and time, filtering, and statistics. Finally, you’ll delve into advanced topics such as how the formula and storage engines work to optimize queries. By the end of this book, you’ll have gained hands-on experience in employing DAX to enhance your data models by extracting new information and gaining deeper insights.
Table of Contents (18 chapters)
Section 1: Introduction to DAX for the BI Pro
Section 2: Understanding DAX Functions and Syntax
Section 3: Taking DAX to the Next Level

Introduction to the DAX calculation engines

Before we start looking at using tools to help us to optimize our DAX queries, we need to understand a little bit about the tabular query engine architecture.

When you execute a DAX query using the in-memory mode, it uses two different engines to run the calculations and come back with a result. These two engines are known as the Formula Engine (FE) and the Storage Engine (SE), and they work together in different roles to calculate the result of DAX queries.

If you execute a DAX query using DirectQuery mode, then the query engine simply coverts the DAX into a SQL statement and sends it to be executed by the external SQL Server. The query engine does no further work other than return the query result that it receives back from SQL Server.

When a DAX query is executed, a combination of the function engine and the storage engine is used...