DB Design for a Startup: Keep It Simple

Start Simple: The Reality of Database Scale

Proof It Works

When to Actually Scale

Clear Signals (Not Hunches)

1. Your database vendor tells you: AWS RDS has a max instance size. When you hit it, time to consider options.

2. Costs become unreasonable: If database costs exceed $10K/month on a single instance

3. Global latency requirements: Users in Australia complaining about 500ms latency

4. Sustained load, not spikes: Consistent 10K+ requests/second (not Black Friday spikes)

The Progressive Enhancement Path

Level 1: Managed PostgreSQL (AWS RDS, Cloud SQL) → Product-market fit  
Level 2: Add Redis + read replicas OR AWS Aurora or Goog AlloyDB → Scale phase
Level 3: Custom sharding → Only if you're Uber

Three Rules for Startup Success

1. PostgreSQL + Managed Services

2. Design for 10x, Not 1000x

• Current: 1K users → Design for: 10K users

• Current: 10K users → Design for: 100K users

• Never design for 1B users on day one

3. Monitor These 3 Metrics

• Query latency > 100ms → Optimize queries

• CPU > 80% → Scale up instance

• Connections > 80% → Add connection pooler

Common Startup Mistakes to Avoid

❌ Mistake 1: Over-Engineering from Day One

# DON'T DO THIS for your MVP
architecture = {
    'microservices': 12,
    'databases': ['PostgreSQL', 'MongoDB', 'Redis', 'Elasticsearch'],
    'message_queues': ['Kafka', 'RabbitMQ'],
    'orchestration': 'Kubernetes',
    'team_size': 2  # 
}

# DO THIS instead
architecture = {
    'monolith': 'React + PostgreSQL',
    'deployment': 'Vercel' or 'GCP' or 'AWS',
    'team_size': 2  # 
}

❌ Mistake 2: Don't paint yourself into NoSQL corner for Wrong Reasons; use JSONB

// DocumentDBs OR NoSQL DBs: Great for MVPs AND real-time (e.g., Firebase, MongoDB)
// But Harder for transactions & joins
// PostgreSQL JSON: Best of both worlds

// Instead of MongoDB documents:
CREATE TABLE orders (
  id SERIAL PRIMARY KEY,
  user_id INTEGER REFERENCES users(id),
  items JSONB,  -- Flexible schema for prototyping where needed
  created_at TIMESTAMP
);
// Get consistency + flexibility

❌ Mistake 3: DIY Database Management

Every hour spent on database ops is an hour not spent on your product. Use AWS RDS, Cloud SQL, or Azure Database. Period.

The Only Takeaway You Need

PostgreSQL on AWS RDS/Cloud SQL/Azure will handle your first 10 million users.

Stop worrying about scale. Start worrying about product-market fit.