Tech Comparisons
SQL vs NoSQL
Choosing between SQL and NoSQL databases impacts your application's scalability, data integrity, and development speed. Both have distinct advantages.
| Feature | SQL | NoSQL |
|---|---|---|
| Data Model | Structured tables with predefined schema. Rows and columns. | Flexible documents, key-value, graph, or column-family. Schema-less or dynamic schema. |
| Scalability | Vertical scaling (bigger servers). Horizontal scaling is complex. | Horizontal scaling (add more servers). Built for distributed systems. |
| ACID Compliance | Strong ACID guarantees. Transactions are reliable. | Eventual consistency. Some support ACID, but often sacrifice it for performance. |
| Query Language | SQL - standardized, powerful query language. | Varies by database (MongoDB Query Language, Cassandra CQL, etc.). |
| Relationships | Built-in JOINs. Excellent for complex relationships. | Joins are difficult or unsupported. Denormalization common. |
SQL Pros & Cons
Pros
- ACID compliance for data integrity
- Powerful JOIN operations
- Mature ecosystem and tooling
- Standardized SQL language
Cons
- Difficult horizontal scaling
- Rigid schema changes
- Not ideal for unstructured data
- Sharding complexity
NoSQL Pros & Cons
Pros
- Easy horizontal scaling
- Flexible, dynamic schemas
- High performance for specific use cases
- Better for unstructured data
Cons
- Eventual consistency challenges
- Weaker transactional support
- No standardized query language
- Data duplication common
Verdict
Use SQL for applications requiring strong consistency, complex relationships, and ACID transactions (banking, e-commerce, ERP). Use NoSQL for high-scale applications, flexible schemas, and when horizontal scaling is critical (social media, IoT, real-time analytics). Many modern apps use both (polyglot persistence) for different data needs.