Week 5/33: Data Modelling for Data Engineering Interviews (Part #2)

Week 5 of 33-Week Data Engineering Interview Guide

In this post, we explore common data modelling interview topics by solving interview questions, including:

• Normalised Forms

• Types of Slowly Changing Dimensions (SCDs)

• Differences between the Kimball and Inmon approaches

• The concept of "One Big Table"

Additionally,

• We solve a case study on converting data tables into 3NF form.

• We solve a case study on SCDs and Star Schema.

• We share resources for a mock Airbnb data modelling interview to help you practise.

In the first post of this series, we covered key concepts such as:

• Definitions of data modelling

• Types of data models

• ER diagrams

• Distinctions between OLTP and OLAP systems

If you haven’t already, check out the post below for a strong foundation:

Week 4/33: Data Modelling for Data Engineering Interviews (Part #1)

Importance of Data Modelling Interviews

Data modelling interviews assess a data engineer’s ability to turn business needs into effective data solutions. Success requires both technical expertise and strong communication skills. During these interviews, asking clarifying questions can provide additional context, as interviewers often reveal more details during discussions.

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Question 1

Case Study: Normalising Data to 3NF

Identify the current form of the given data and normalise it to 3NF.

We are provided with the above tables. We start by identifying their current form (e.g., 1NF, 2NF, 3NF). If the tables are not in 3NF, we explain the steps to normalise them.