Book Image

Learning Elasticsearch

By : Abhishek Andhavarapu
Book Image

Learning Elasticsearch

By: Abhishek Andhavarapu

Overview of this book

Elasticsearch is a modern, fast, distributed, scalable, fault tolerant, and open source search and analytics engine. You can use Elasticsearch for small or large applications with billions of documents. It is built to scale horizontally and can handle both structured and unstructured data. Packed with easy-to- follow examples, this book will ensure you will have a firm understanding of the basics of Elasticsearch and know how to utilize its capabilities efficiently. You will install and set up Elasticsearch and Kibana, and handle documents using the Distributed Document Store. You will see how to query, search, and index your data, and perform aggregation-based analytics with ease. You will see how to use Kibana to explore and visualize your data. Further on, you will learn to handle document relationships, work with geospatial data, and much more, with this easy-to-follow guide. Finally, you will see how you can set up and scale your Elasticsearch clusters in production environments.
Table of Contents (11 chapters)
10
Exploring Elastic Stack (Elastic Cloud, Security, Graph, and Alerting)

Primary and Replica shards

As you know the data in an index is split across one or more shards. By splitting your data across multiple shards, Elasticsearch can scale beyond what a single machine can do. Elasticsearch is a distributed system, and system failures are bound to happen. Since each shard is an independent Lucene index that can live on any node in the cluster, Elasticsearch provides a way to maintain a copy of the primary shard in a different node of the cluster. In case the node containing the primary shard fails, the replica shard (copy), which exists in a different node, is promoted to primary. For more information, please refer to the Failure Handling section in Chapter 1, Introduction to Elasticsearch.

In this section, we will talk about how the data between primary and replica is synchronized:

Let's say we have a cluster of two nodes as shown in the preceding...