Django ORM is dangerous because it's too convenient. You write "task.owner.name" inside a loop, and it just works. Python is happy. You are happy. Database is crying. I recently checked an endpoint that felt a bit sluggish. I opened Django Debug Toolbar and... oh. 150 SQL queries for one page load. I was accidentally asking the database for the "owner" inside every single iteration of the loop. The classic N+1 problem. The fix was embarrassingly simple: Task.objects.select_related('owner') That’s it. One line change. 150 queries turned into 1. The moral of the story: ORM is great, but never trust "magic" blindly. Always look under the hood. #python #django #performance #backend #sql
Nice insight. When something seems too easy with an ORM, it's often a sign there's complexity hiding underneath. Your post is a great reminder that convenience shouldn’t replace awareness tools like select_related and Django Debug Toolbar are essential for writing efficient, scalable code. Thanks for sharing this practical lesson brother
That’s why interviewers love to ask about the N+1 problem and the difference between select_related and prefetch_related. Also, Django ORM is great for simple queries, but the more complex your queries become, the more painful it gets - often to the point where you want to switch to raw SQL.
Great example! Depending on the logic, we can add .only() for fetching the required column, or if we don't need model instances, we can just use owner__name in values method.
Exactly classic N+1 issue. Django ORM makes relations feel too easy, so most of the time you don’t even realize what’s going on under the hood until things get slow. related_name is just for cleaner reverse access, it doesn’t help with performance at all. For N+1 you still have to be deliberate with select_related (FK / OneToOne) and prefetch_related (M2M / reverse FK). ORM is great, but you still need to know what SQL it’s actually generating. Debug Toolbar honestly saves you from embarrassing stuff like this 😅
ORM is not great. It was created by college persons to college persons and buisness loves that worker has to know only python and not sql. And it will dissappear as persons who sit days to create html css buttons and studied it years. SQL will stay. You cannot create really complicated queries and tuning them with ORM. Buisness just add more and more machine resource instead of optimise queries. And its gooood! Stupid people should pay more and more and more.
Django uses specific methods to solve the N+1 query problem, making your application significantly faster select_related(*fields) used for to get data from table related with ForeignKey and OneToOne relationships. And prefetch_related(*lookups) use for ManyToMany and reverse ForeignKey (Multi-valued). The use of defer() and only() with these queries make the data fetching more fast.
Lots of pages execute 80-120 queries per single page
Use Silk and optimize your query
The N+1 problem is such a classic trap because the ORM makes everything look so clean on the surface. It is wild how a single line like select_related can be the difference between a snappy app and a total database meltdown. I had a similar moment recently where a simple loop was killing our latency and the fix felt almost too easy. It is a good reminder that convenience always comes with a price and you really have to keep that django debug toolbar open.