Key–Value Databases and Riak

 

Key–Value and Graph Databases

Key–Value Databases and Riak

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1. Key–Value Databases

Meaning

A key–value database stores data as a pair of key and value.

• Key → Unique identifier

• Value → Actual data (string, JSON, object, etc.)

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Characteristics

• Simple data model

• Very fast data access

• Highly scalable

• No complex queries

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Examples

• Riak

• Redis

• Amazon DynamoDB

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Advantages

• High performance

• Easy to scale

• Suitable for distributed systems

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Limitations

• No joins

• Limited querying

• Not suitable for complex relationships

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2. Riak – Key–Value Database

Introduction

Riak is a distributed, highly available key–value NoSQL database designed for fault tolerance and scalability.

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Key Features of Riak

1. Simple Key–Value Storage

• Data stored as key–value pairs

• Easy read/write operations

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2. High Availability

• No single point of failure

• Uses replication across nodes

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3. Eventual Consistency

• Data may be temporarily inconsistent

• Eventually becomes consistent

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4. Horizontal Scalability

• Add or remove nodes easily

• No downtime during scaling

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5. Fault Tolerance

• Automatically handles node failures

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Riak Architecture (Brief)

• Peer-to-peer architecture

• Uses consistent hashing

• All nodes are equal

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3. Use Cases of Riak

• Session storage

• User profiles

• Shopping cart data

• Cache data

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4. Graph Databases (Brief Overview)

Meaning

Graph databases store data as:

• Nodes (entities)

• Edges (relationships)

• Properties (data)

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Example

• Neo4j

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Best Used For

• Social networks

• Recommendation systems

• Fraud detection

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5. Comparison: Key–Value vs Graph Databases

Aspect	Key–Value DB	Graph DB
Data model	Key–value	Nodes & edges
Query type	Simple	Relationship-based
Use case	Fast access	Complex relations