Django QuerySet Optimization: How to Efficiently Retrieve Related Objects Using Prefetch Related?
I've hit a wall trying to I'm dealing with I'm working on a project and hit a roadblock... I'm currently facing performance issues with my Django application where I'm trying to retrieve related objects. My models are structured with a ForeignKey relationship, and I'm attempting to fetch a list of `Book` objects along with their associated `Author` objects. Here’s what I’ve tried: ```python # models.py class Author(models.Model): name = models.CharField(max_length=100) class Book(models.Model): title = models.CharField(max_length=200) author = models.ForeignKey(Author, on_delete=models.CASCADE) ``` In my view, I'm currently using: ```python # views.py from .models import Book books = Book.objects.all() # This is causing N+1 queries ``` I read about using `prefetch_related()` to minimize the number of queries. However, when I try to implement it like this: ```python books = Book.objects.prefetch_related('author').all() ``` it returns the correct data, but I'm still worried about performance. The query seems to take quite a while with a large dataset, and I want to ensure I'm using Django's ORM effectively. Specifically, I’ve noticed that the SQL generated looks a bit excessive. Here’s the SQL query that gets executed: ```sql SELECT "app_book".*, "app_author".* FROM "app_book" LEFT OUTER JOIN "app_author" ON ("app_book"."author_id" = "app_author"."id"); ``` My main concern is how to properly use `prefetch_related` or if there are other optimizations I should consider. I'm using Django version 3.2.8. Is there a better approach or best practice that I should be following to optimize this query further? Any insights or recommendations would be greatly appreciated! I'm working on a API that needs to handle this. Is there a better approach? This issue appeared after updating to Python stable. Thanks, I really appreciate it!