Book Image

Mastering Elasticsearch 5.x - Third Edition

By : Bharvi Dixit
Book Image

Mastering Elasticsearch 5.x - Third Edition

By: Bharvi Dixit

Overview of this book

Elasticsearch is a modern, fast, distributed, scalable, fault tolerant, and open source search and analytics engine. Elasticsearch leverages the capabilities of Apache Lucene, and provides a new level of control over how you can index and search even huge sets of data. This book will give you a brief recap of the basics and also introduce you to the new features of Elasticsearch 5. We will guide you through the intermediate and advanced functionalities of Elasticsearch, such as querying, indexing, searching, and modifying data. We’ll also explore advanced concepts, including aggregation, index control, sharding, replication, and clustering. We’ll show you the modules of monitoring and administration available in Elasticsearch, and will also cover backup and recovery. You will get an understanding of how you can scale your Elasticsearch cluster to contextualize it and improve its performance. We’ll also show you how you can create your own analysis plugin in Elasticsearch. By the end of the book, you will have all the knowledge necessary to master Elasticsearch and put it to efficient use.
Table of Contents (20 chapters)
Mastering Elasticsearch 5.x - Third Edition
About the Author
About the Reviewer
Customer Feedback

Routing explained

In the Choosing the right amount of shards and replicas section in this chapter, we mentioned routing as a solution for the shards on which queries will be executed on a single one. Now it's time to look closer at this functionality.

Shards and data

Usually, it is not important how Elasticsearch divides data into shards and which shard holds the particular document. During query time, the query will be sent to all the shards of a particular index, so the only crucial thing is to use the algorithm that spreads our data evenly so that each shard contains similar amounts of data. We don't want one shard to hold 99 percent of the data while the other shard holds the rest--it is not efficient.

The situation complicates slightly when we want to remove or add a newer version of the document. Elasticsearch must be able to determine which shard should be updated. Although it may seem troublesome, in practice, it is not a huge problem. It is enough to use the sharding algorithm, which...