Book Image

Elasticsearch 5.x Cookbook - Third Edition

By : Alberto Paro
Book Image

Elasticsearch 5.x Cookbook - Third Edition

By: Alberto Paro

Overview of this book

Elasticsearch is a Lucene-based distributed search server that allows users to index and search unstructured content with petabytes of data. This book is your one-stop guide to master the complete Elasticsearch ecosystem. We’ll guide you through comprehensive recipes on what’s new in Elasticsearch 5.x, showing you how to create complex queries and analytics, and perform index mapping, aggregation, and scripting. Further on, you will explore the modules of Cluster and Node monitoring and see ways to back up and restore a snapshot of an index. You will understand how to install Kibana to monitor a cluster and also to extend Kibana for plugins. Finally, you will also see how you can integrate your Java, Scala, Python, and Big Data applications such as Apache Spark and Pig with Elasticsearch, and add enhanced functionalities with custom plugins. By the end of this book, you will have an in-depth knowledge of the implementation of the Elasticsearch architecture and will be able to manage data efficiently and effectively with Elasticsearch.
Table of Contents (25 chapters)
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface

Counting matched results


It is often required to return only the count of the matched results and not the results themselves.

There are a lot of scenarios involving counting, such as the following:

  • To return the number of something (how many posts for a blog, how many comments for a post)

  • Validating whether some items are available. Are there posts? Are there comments?

Getting ready

You will need an up-and-running Elasticsearch installation as used in the Downloading and installing Elasticsearch recipe in Chapter 2, Downloading and Setup.

To execute curl via a command line, you need to install curl for your operating system.

To correctly execute the following commands, you will need an index populated with the chapter_05/populate_query.sh script available in the online code.

How to do it...

In order to execute a counting query, we will perform the following steps:

  1. From the command line, we will execute a count query, as follows:

        curl -XGET 'http://127.0.0.1:9200/test-index/test-type/_count? 
    ...