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

Lucene expressions

Lucene expressions are a very powerful tool for easy scoring adjustments, without writing custom Java code. The thing that makes Lucene expressions very handy is that using them is very fast-their execution is as fast as native scripts since each expression is compiled to Java bytecode, to achieve native code-like performance, yet they are like dynamic scripts with some limitations. This section will show you what you can do with Lucene expressions.

The basics

Lucene provides functionality to compile a JavaScript expression to a Java bytecode. This is how Lucene expressions work and why they are as fast as native Elasticsearch scripts. Lucene expressions can be used in the following Elasticsearch functionalities:

  • Scripts responsible for sorting

  • Aggregations that work on numeric fields

  • In the function_score query under the script_score query

  • In queries using script_fields

In addition to this, you have to remember that:

  • Lucene expressions can be only used on numeric fields

  • Stored...