Which statement best contrasts relational databases with NoSQL databases in an MIPC context, and when would you choose relational?

• A. Relational databases enforce fixed schemas and ACID transactions; NoSQL databases offer flexible schemas and varying consistency; choose relational when data is highly structured and you need strong transactional integrity.
• B. NoSQL databases enforce fixed schemas and SQL; choose NoSQL when you need strong transactional integrity.
• C. Relational databases support flexible schemas and eventual consistency; NoSQL is best for large-scale, complex joins.
• D. NoSQL databases always provide stronger cross-table joins and should replace relational databases for all workloads.

Answer: (A)

Relational databases rely on a fixed schema and provide ACID transactions, which guarantees reliable, consistency-focused operations even across multiple steps. NoSQL systems, by contrast, prioritize flexible schemas and a range of consistency models (often eventual consistency) to scale horizontally. Because of that, relational databases are the better choice when the data is highly structured and you need strong transactional integrity across operations.

The other statements mischaracterize NoSQL or relational features: NoSQL doesn’t typically enforce fixed schemas or rely on SQL in the way the option suggests; relational systems do more than just offer strong consistency, including robust joins and structured data integrity; and NoSQL generally does not excel at cross-table joins and is not intended to replace relational databases for all workloads.