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

Chapter 2. The Improved Query DSL

In the previous chapter, we looked at the overview of Lucene, how it works, how analysis processing is done, and how to use the Apache Lucene query language. In addition to that, we discussed the basic concepts of Elasticsearch. We also introduced Elasticsearch 5.x and covered the latest features introduced in version 2.x as well as 5.x. We also talked about the most important changes/removals of features Elasticsearch has gone through during the transition from 1.x to 5.x. In this chapter, we will dive deep into Elasticsearch, focusing on the Query DSL. We will first go through Lucene similarity algorithm formulas before turning to advanced queries. By the end of this chapter, we will have covered the following topics:

  • The changed default text scoring in Lucene: BM25

  • Understanding precision and recall

  • How BM25 differs from TF-IDF

  • Elasticsearch Query DSL

  • Understanding bool query syntax

  • Which query you should use for your particular use case

  • Important changes in...