Data Modeling Explained in 3 Minutes

[00:00:00]Hi everyone. In this module, we are going to be learning about data modeling and some of the related concepts. Now, if you're planning for a data engineering role, then data modeling becomes extremely important. In most cases, you will at least have one round related to data modeling. And beyond interviews, data modeling is a fundamental skill that will help you design better systems when you're working on a real-world data project.

[00:00:24]And that is exactly why I have included data modeling as one of the modules in this course. Now, let's start this module by first understanding what exactly is data modeling. Now, imagine that you're building a house. The first thing that you will need to do is to kind of first create a blueprint of the house that you want to build, right?

[00:00:46]Now, blueprint is not something where you're going to live, but it's going to tell you exactly what you need to build, right? Where the walls will stand, where the doors will open, how the plumbing will run, etc. etc. Now, imagine if your blueprint had mistakes. Maybe the wall was in the wrong place, or the plumbing wasn't planned properly. Now, fixing these issues after construction starts would be very painful, time-consuming, and very expensive. But, when the blueprint is solid, everything that follows just falls into place. Now, data modeling works exactly in the same way, but for databases. Before you write a single line of SQL, you step back and think, "What data does my system actually need? What should I call these entities? And how do they connect with each other?"

[00:01:35]For example, you might ask, "Do I need a customer entity? Can a customer have multiple addresses?" Or let's say, "Can one order include multiple books?" Now, these are the kind of questions that you answer during the data modeling phase.

[00:01:50]Usually on a paper, or using a diagram.

[00:01:54]And this comes much before starting to write SQL scripts. Now, if you skip this step, then things can quickly get chaotic. Every time you have a new requirement, you might have to end up doing a quick patch, or you might have to create some new columns, or create some new tables, and very quickly your database will become messy and hard to manage. But, when you take your time to model your data properly up front, something interesting happens. The SQL you write later on doesn't feel complicated, it feels obvious. So, I hope you kind of understand this example. In short, data modeling is the process of kind of creating a blueprint of the database or the data warehouse that you want to work with, right? So, you need to decide what data you're going to get, how you're going to store that data, how the data is going to be connected to each other. So, the complete blueprint of your database or your data warehouse. Once this blueprint is ready, you start developing this database or kind of creating all the tables and every other objects, and uploading the data. It all comes later.

[00:02:59]First, you need to have the data model ready. Once you have the data model ready, only then you start actually doing the SQL work. Okay? So, I hope you get the gist of what data modeling is.