Which statement best describes NoSQL databases relative to relational databases?

• A. They strictly require fixed schemas and SQL.
• B. They support flexible schemas and non-relational models.
• C. They cannot scale horizontally.
• D. They always enforce ACID across all operations.

Answer: (B)

NoSQL databases are built to handle varied and evolving data without forcing a rigid, predefined structure. They embrace non-relational data models—such as document, key-value, graph, or wide-column stores—so each record can have a different set of fields or nested data. This flexibility is a core feature, especially when data schemas can change over time or when you need to store complex, nested information. Along with this, NoSQL systems are designed to scale out easily across many machines, which supports large-scale applications and big data needs. In practice, many NoSQL solutions relax strict ACID guarantees in favor of performance and availability, offering eventual consistency rather than every operation being strictly ACID-compliant. So the statement that best describes NoSQL databases relative to relational databases is that they support flexible schemas and non-relational models. The other descriptions don’t fit because fixed schemas and SQL, lack of horizontal scaling, or universal ACID enforcement don’t align with how NoSQL systems are typically designed.