ELK Stack — Elasticsearch Fundamentals

Elasticsearch Fundamentals

Elasticsearch is the heart of the ELK Stack — a distributed search and analytics engine that stores, indexes, and searches your data. In this chapter, you’ll learn the core concepts that everything else builds on.

Think of Elasticsearch as a database specifically designed for searching. While PostgreSQL or MySQL are great for transactions, Elasticsearch is built for fast, full-text search across millions of documents.

What You’ll Learn

• How indices and documents work (Elasticsearch’s storage model)
• Mappings — the schema that defines your data structure
• Shards and replicas — how Elasticsearch distributes and protects data
• CRUD operations — creating, reading, updating, and deleting documents
• The REST API — how to interact with Elasticsearch via HTTP

Chapter Contents

#	Topic	Description
1	Indices & Documents	The fundamental building blocks of Elasticsearch
2	Mappings	Define field types and analyzers for your data
3	Shards & Replicas	How Elasticsearch distributes and replicates data
4	CRUD Operations	Create, read, update, and delete documents
5	REST API	Interact with Elasticsearch via HTTP
6	Practice Exercises	5 hands-on exercises

Prerequisites

• Elasticsearch 8.x running (Docker Compose or standalone)
• curl available in your terminal
• Basic JSON knowledge

Let’s start with the foundation — indices and documents.