Big Data

Big Data Chapter 6 – NoSQL Databases | MongoDB and Cassandra Explained

NoSQL Databases in Big Data (MongoDB and Cassandra)

Traditional relational databases struggle with scalability, flexibility, and
performance when handling massive volumes of unstructured and semi-structured data.
NoSQL databases were designed to overcome these limitations.

In Big Data systems, NoSQL databases provide high availability, horizontal scalability,
and fast read-write performance. This chapter introduces NoSQL concepts with a focus
on MongoDB and Cassandra.

⭐ What is NoSQL?

NoSQL (Not Only SQL) databases are non-relational databases designed to store and
process large-scale data efficiently. They support flexible schemas and distributed
architectures.

📌 Why NoSQL Databases are Needed

  • Handles massive data volumes
  • Supports unstructured and semi-structured data
  • Horizontal scalability
  • High availability and fault tolerance
  • Low-latency read and write operations

📌 Types of NoSQL Databases

  • Key-Value Stores: Redis, DynamoDB
  • Document Databases: MongoDB
  • Column-Family Stores: Cassandra, HBase
  • Graph Databases: Neo4j

⭐ MongoDB (Document-Based NoSQL Database)

MongoDB is a document-oriented NoSQL database that stores data in JSON-like
documents called BSON. It is widely used for applications that require flexibility
and rapid development.

📌 Features of MongoDB

  • Schema-less document structure
  • High performance and scalability
  • Easy integration with applications
  • Rich querying capabilities

📌 MongoDB Example


// Insert document
db.users.insertOne({
  name: "John",
  age: 30,
  skills: ["Python", "Big Data"]
})

// Find documents
db.users.find({ age: { $gt: 25 } })

📌 MongoDB Use Cases

  • Content management systems
  • Real-time analytics
  • Mobile and web applications

⭐ Apache Cassandra (Column-Family NoSQL Database)

Apache Cassandra is a highly scalable and distributed NoSQL database designed
for handling large amounts of data across multiple nodes with no single point
of failure.

📌 Features of Cassandra

  • Peer-to-peer architecture
  • Linear scalability
  • High availability
  • Optimized for write-heavy workloads

📌 Cassandra Data Model

  • Keyspace
  • Tables
  • Rows and columns
  • Partition keys and clustering keys

📌 Cassandra Example


CREATE TABLE users (
  user_id UUID PRIMARY KEY,
  name text,
  age int
);

INSERT INTO users (user_id, name, age)
VALUES (uuid(), 'Alice', 28);

📌 Cassandra Use Cases

  • Time-series data storage
  • IoT applications
  • Messaging platforms
  • High-volume transactional systems

📌 MongoDB vs Cassandra

  • MongoDB: Flexible schema, rich queries
  • Cassandra: High write throughput, massive scalability

📌 Real-Life Applications

  • Netflix streaming data
  • Social media platforms
  • Online gaming systems
  • E-commerce personalization

📌 Project Title

Scalable Big Data Storage Using MongoDB and Cassandra

📌 Project Description

In this project, you will design a Big Data storage solution using MongoDB
for flexible document storage and Cassandra for high-speed, distributed
data access. This project demonstrates how NoSQL databases are used in
modern Big Data architectures.

📌 Summary

NoSQL databases play a critical role in Big Data systems by enabling scalable,
flexible, and high-performance data storage. MongoDB and Cassandra address
different Big Data needs and are widely adopted in enterprise applications.
This chapter completes your Big Data Technologies course.

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