Book Image

Elasticsearch Server - Third Edition

By : Rafal Kuc
Book Image

Elasticsearch Server - Third Edition

By: Rafal Kuc

Overview of this book

ElasticSearch is a very fast and scalable open source search engine, designed with distribution and cloud in mind, complete with all the goodies that Apache Lucene has to offer. ElasticSearch’s schema-free architecture allows developers to index and search unstructured content, making it perfectly suited for both small projects and large big data warehouses, even those with petabytes of unstructured data. This book will guide you through the world of the most commonly used ElasticSearch server functionalities. You’ll start off by getting an understanding of the basics of ElasticSearch and its data indexing functionality. Next, you will see the querying capabilities of ElasticSearch, followed by a through explanation of scoring and search relevance. After this, you will explore the aggregation and data analysis capabilities of ElasticSearch and will learn how cluster administration and scaling can be used to boost your application performance. You’ll find out how to use the friendly REST APIs and how to tune ElasticSearch to make the most of it. By the end of this book, you will have be able to create amazing search solutions as per your project’s specifications.
Table of Contents (18 chapters)
Elasticsearch Server Third Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Scripting capabilities of Elasticsearch


Elasticsearch has a few functionalities where scripts can be used. You've already seen examples such as updating documents and searching. We will also use the scripting capabilities of Elasticsearch when we discuss aggregations. Even though scripts seem to be a rather advanced topic, we will look at the possibilities offered by Elasticsearch. That's because scripts are priceless in certain situations.

Elasticsearch can use several languages for scripting. When not explicitly declared, it assumes that Groovy (www.groovy-lang.org/) is used. Other languages available out of the box are Lucene expression language and Mustache (https://mustache.github.io/). Of course we can use plugins, which will make Elasticsearch understand additional scripting languages, such as JavaScript, MVEL, and Python. The thing worth mentioning is that independent from the scripting language that we choose, Elasticsearch exposes objects that we can use in our scripts. Let's start...