NoSQL Data Models

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1. Introduction

NoSQL databases do not use the traditional table-based relational model.
Instead, they use flexible data models depending on the application and data type.

Main NoSQL data models:

1. Key–Value

2. Document-Oriented

3. Column-Family

4. Graph

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2. Key–Value Data Model

Definition

Stores data as a pair of key and value, similar to a dictionary.

Structure

Key → Value

Features

• Simple and fast

• Schema-less

• Supports distributed storage

Examples

• Redis, Riak, Amazon DynamoDB

Use Cases

• Session management

• Caching

• User profiles

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3. Document-Oriented Data Model

Definition

Stores data in the form of documents (usually JSON or BSON).

Structure

• Document = Object

• Documents are grouped into collections

Features

• Flexible schema

• Can store nested data

• Supports indexing and querying

Examples

• MongoDB, CouchDB

Use Cases

• Content management systems

• E-commerce platforms

• Real-time analytics

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4. Column-Family Data Model

Definition

Stores data in columns and column families, not rows.
Good for large datasets and distributed systems.

Structure

• Row key

• Column families

• Columns within families

Features

• High scalability

• Fast writes

• Supports distributed clusters

Examples

• Apache Cassandra, HBase

Use Cases

• Time-series data

• Event logging

• Analytics

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5. Graph Data Model

Definition

Stores data as nodes, relationships, and properties.

Structure

• Nodes = entities

• Relationships = connections

• Properties = additional info

Features

• Optimized for relationship-heavy data

• Supports fast graph traversals

Examples

• Neo4j, JanusGraph

Use Cases

• Social networks

• Recommendations

• Fraud detection

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6. Summary Table

Data Model	Structure	Best For
Key–Value	Key → Value	Caching, sessions
Document	JSON / BSON Documents	Flexible data storage
Column-Family	Columns & Families	Big data & analytics
Graph	Nodes & Relationships	Connected data