In the previous 11 chapters, we learned about various aspects of data modeling to model many different scenarios. This chapter focuses on implementing more advanced data warehousing concepts in Power BI, which become handy in more complex real-world scenarios. This chapter covers the following areas:
The term slowly changing dimensions, or in short, SCD, is a data warehousing concept introduced by the amazing Ralph Kimball. You can learn more about Ralph Kimball here: https://www.kimballgroup.com/about-kimball-group/.
The SCD concept deals with moving a specific dataset from one state to another. Let us look at SCD in more detail with a scenario.
The Adventure Works organization has a human resources (HR) system in which its data is captured in the organization’s data warehouse. Stephen Jiang is a Sales Manager with 10 sales representatives on his team. The source for this scenario is the AdventureWorksDW2019 database, which you can download from here: https://learn.microsoft.com/en-us/sql/samples/adventureworks-install-configure?view=sql-server-ver16&WT.mc_id=DP-MVP-5003466.
The following image shows the sample data for our scenario:
Figure 12.1: Stephen Jiang is the sales manager of a team of 10 sales representatives
Brian...
The term “degenerate dimension” was coined by the amazing Ralph Kimball. Learn more about the Kimbal Group here: https://www.kimballgroup.com/.
The Kimball Group refers to Webster to define the meaning of the term “degenerate” as follows:
According to Webster, “degenerate” refers to something that’s 1) declined from the standard norm, or 2) is mathematically simpler.
Read the full article here: https://www.kimballgroup.com/2003/06/design-tip-46-another-look-at-degenerate-dimensions/.
From a Star Schema standpoint, degenerate dimensions are the dimension key attributes appearing in the fact tables without having their own dimension. In other words, we do not create a separate dimension table for them. But as we know, from a Star Schema perspective, it is not a good practice to put dimension attributes in the fact tables. So a degenerate dimension, according to Webster’...
In this chapter, we learned about the concept of SCD and how to implement some related scenarios. We also learned more about degenerate dimensions and how to deal with them in our data models in Power BI. The next chapter explains the purely cloud-based data transformation capability in Power BI called Dataflows.
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