Q1: What is the difference between SQL (Relational) and NoSQL (Non-Relational) databases?
SQL databases are relational, structured, and enforce a predefined schema. They store data in tables composed of rows and columns, leveraging ACID properties to guarantee transactional consistency.
NoSQL databases are non-relational, schema-flexible, and designed for horizontal scalability across distributed clusters. They utilize dynamic data models including Key-Value pairs, Document stores (JSON/BSON), Wide-Column stores, and Property Graphs.
SQL vs NoSQL Architectural Comparison
Data Model:
Relational Tables vs Key-Value / Document / GraphSQL uses strict normalized schema tables; NoSQL uses flexible dynamic documents.
Scaling:
Vertical (Scale-Up) vs Horizontal (Scale-Out)SQL scales via larger hardware resources; NoSQL scales by adding nodes to a cluster.
Guarantees:
ACID vs BASE (Eventually Consistent)SQL focuses on immediate consistency; NoSQL often prioritizes high availability.
Key Takeaways
- SQL databases excel at complex JOIN queries and strict transactional consistency (ACID).
- NoSQL databases excel at handling unstructured or rapidly changing data at massive distributed scale.