Understanding select_related and prefetch_related in Django by akshaythekkath ( https://hashnode.com/@akshaythekkath )

• https://blog.akshaythekkath.com/understanding-selectrelated-and-prefetchrelated-in-django

Introduction

When I started learning Django, the one thing that fascinated me a lot was the Django ORM.

Maybe I was happy that I will not have to write SQL queries and can skip all the pain of writing crazy joins to fetch the data.

I was throwing in objects.all() and objects.filter(…) with joy all around my application. Until I reached a point where I had a lot of data in the system and it started to lag .

Sometimes as ORM users, we don’t bother to see the underlying SQL query that is being built, or how many queries are fired ? which becomes expensive over time.

My perspective started to change . I started thinking in SQL first and then how to query the Django ORM so that it builds the desired SQL query. With this approach, I started optimizing the queries and the latency of my APIs began to drop.