System Design Basics: Building Scalable Applications

System design is crucial for building applications that can handle millions of users. Here are the fundamental concepts.

Core Principles

1. Scalability

Horizontal Scaling: Add more servers

Vertical Scaling: Increase server capacity

2. Load Balancing

Distribute traffic across multiple servers:

3. Caching

Store frequently accessed data in fast storage:

# Example: Redis caching
import redis

cache = redis.Redis()

def get_user(user_id):
    # Check cache first
    cached = cache.get(f"user:{user_id}")
    if cached:
        return json.loads(cached)
    
    # Fetch from database
    user = db.get_user(user_id)
    
    # Store in cache
    cache.setex(f"user:{user_id}", 3600, json.dumps(user))
    
    return user

Database Design

SQL vs NoSQL

SQL (Relational):

NoSQL:

Replication

Key Components

Design Process

Start with these fundamentals and build from there!