N+1 Problem — Detection and Solutions

N+1 is the most common performance problem with ORMs. Instead of 1 query you send 101 queries — and the database suffers.

The Problem¶

N+1 Problem — Detection and Solutions¶

users = User.query.all() # 1 query for user in users: print(user.orders) # N queries (1 per user!)

Solution — Eager Loading¶

SQLAlchemy — joinedload¶

users = session.query(User).options(joinedload(User.orders)).all()

Django — select_related / prefetch_related¶

users = User.objects.prefetch_related(‘orders’).all()

Prisma — include¶

const users = await prisma.user.findMany({ include: { orders: true } });

Detection¶

Django — django-debug-toolbar¶

SQLAlchemy — echo=True or sqlalchemy.engine logging¶

nplusone library (Python)¶

pip install nplusone

Key Takeaway¶

Eager loading (joinedload, prefetch_related, include). Detection: debug toolbar, query logging.