Context

Teams at companies like Notion often choose between PostgreSQL and a NoSQL store when designing a new product feature. Interviewers ask this to test whether you understand data modeling trade-offs, not just tool names.

Core question

Explain the trade-offs between using SQL and NoSQL databases. In your answer, discuss:

1. How their data models differ
2. When each is a better fit
3. Trade-offs around consistency, scalability, and query patterns
4. How schema design affects development speed and long-term maintenance

Scope guidance

Keep your answer practical and balanced. You do not need to argue that one is always better. A strong answer should compare common relational systems such as PostgreSQL with common NoSQL patterns such as document, key-value, or wide-column stores, and explain how workload requirements drive the choice.