SQL vs NoSQL trade-offs

Problem Compare a relational database (PostgreSQL) with NoSQL stores (Cassandra/MongoDB) and explain when you would choose each.

Be ready to discuss

• Data model fit: relational/normalized vs document vs wide-column.
• Indexing, and read vs write scaling (single-primary + replicas vs partitioned/leaderless).
• Consistency models: ACID transactions vs BASE / tunable consistency.
• Concrete selection criteria: query patterns, scale, consistency needs, and operational cost.