What is a common trade-off observed in NoSQL systems relative to relational databases?

• A. Strong cross-table joins
• B. Global strong consistency
• C. Varied consistency models, often eventual or tunable
• D. Inability to scale horizontally

Answer: (C)

NoSQL systems commonly trade strict, global consistency for scalability by offering varied consistency models, often eventual or tunable. In distributed environments, achieving high availability and fault tolerance across many nodes means relaxing some of the ACID guarantees that relational databases emphasize. As a result, reads may see stale data for a moment unless you opt for stronger consistency on a per-operation basis. This design enables horizontal scaling and flexible schemas, which is why you see options like eventual consistency or tunable consistency levels in practice. The other ideas—relying on strong cross-table joins, guaranteeing global strong consistency everywhere, or lacking horizontal scaling—don’t reflect the typical priorities of NoSQL systems.