✅ What is NoSQL?
NoSQL stands for “Not Only SQL“. It refers to non-relational databases that store data in formats other than traditional tabular relations used in RDBMS.
Unlike relational databases, which store data in rows and tables, NoSQL databases are non-relational and non-tabular in structure. They are typically schema-less, meaning that they do not require a predefined data structure. This allows for much greater flexibility in storing various types of data.
In NoSQL systems, data is often stored in the form of JSON (JavaScript Object Notation) documents, which makes it easy to represent complex, nested structures—ideal for modern web and mobile applications.
🔶 Key Features of NoSQL Databases
- Schema-less: Flexible schema design (no need to predefine a schema).
- Horizontal scalability: Easy to scale out across multiple servers.
- High availability and fault tolerance.
- Designed for Big Data and real-time applications.
- Support for different data models.
⚡ Use Cases of NoSQL
-
- Real-time analytics
- IoT applications
- Social media platforms
- Content management systems
- Big Data applications
- E-commerce product catalogs
- Mobile app backends
🔄 Types of NoSQL Databases (with Examples)
|
Type |
Description |
Examples |
Use Cases |
|
Document-based |
Stores data in JSON/BSON/XML format documents |
MongoDB, CouchDB |
Content management, blogging platforms |
|
Key-Value |
Data stored as key-value pairs |
Redis, DynamoDB, Riak |
Caching, session storage |
|
Column-family |
Stores data in column families, suitable for wide rows |
Cassandra, HBase |
Time-series data, analytics |
|
Graph-based |
Stores entities as nodes and relationships as edges |
Neo4j, ArangoDB |
Social networks, recommendation engines |
Click here to watch complete playlist on NoSQL
📌 Examples
1. Document-Based (MongoDB)
Flexible: Can add new fields without altering the schema.
{
“name”: “Alice”,
“age”: 25,
“email”: “alice@example.com”,
“skills”: [“Node.js”, “MongoDB”]
}
2. Key-Value (Redis)
Fast: Ideal for caching and real-time applications.
SET username “john_doe”
GET username
3. Columnar (Cassandra)
Rows have variable number of columns.
CREATE TABLE users (
id UUID PRIMARY KEY,
name text,
email text
);
4. Graph-Based (Neo4j)
CREATE (a:Person {name: ‘Alice’})-[:FRIENDS_WITH]->(b:Person {name: ‘Bob’})