Book Image

ElasticSearch Cookbook

By : Alberto Paro
Book Image

ElasticSearch Cookbook

By: Alberto Paro

Overview of this book

ElasticSearch is one of the most promising NoSQL technologies available and is built to provide a scalable search solution with built-in support for near real-time search and multi-tenancy. This practical guide is a complete reference for using ElasticSearch and covers 360 degrees of the ElasticSearch ecosystem. We will get started by showing you how to choose the correct transport layer, communicate with the server, and create custom internal actions for boosting tailored needs. Starting with the basics of the ElasticSearch architecture and how to efficiently index, search, and execute analytics on it, you will learn how to extend ElasticSearch by scripting and monitoring its behaviour. Step-by-step, this book will help you to improve your ability to manage data in indexing with more tailored mappings, along with searching and executing analytics with facets. The topics explored in the book also cover how to integrate ElasticSearch with Python and Java applications. This comprehensive guide will allow you to master storing, searching, and analyzing data with ElasticSearch.
Table of Contents (19 chapters)
ElasticSearch Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Using the top_children query


In the previous recipe, the has_child query consumes a large amount of memory because it requires to fetch IDs of all the children. To bypass this limitation in huge data contexts the top_children query allows fetching only the top children results.

Getting ready

You need a working ElasticSearch cluster and the data populated with the populate script.

How to do it...

For executing the top_children query, we need to perform the following steps:

  1. We need to search the test-type parents of which the test-type2 top children have a term in the field value as value1. We can create this kind of query as follows:

    curl -XPOST 'http://127.0.0.1:9200/test-index/test-type/_search' -d '{
        "query": {
                "top_children" : {
                    "type" : "test-type2",
                    "query" : {
                        "term" : {
                            "value" : "value1"
                        }
                    },
                    "score" : "max",
                    "factor" : 5,
        ...