One of the great features provided by Elasticsearch is the ability to change the ordering of documents after they are returned by a query
. Actually, Elasticsearch does a simple trick-it recalculates the score of top matching documents, so only part of the document in the response is reordered. The reasons why we want to do this can vary. One of the reasons may be performance. For example, calculating target ordering is very costly because scripts are used and we would like to do this on the subset of documents returned by the original query
. You can imagine that rescore
gives us many great opportunities for business use cases. Now, let's look at this functionality and how we can benefit from using it.

Mastering Elasticsearch 5.x - Third Edition
By :

Mastering Elasticsearch 5.x - Third Edition
By:
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
Credits
About the Author
Acknowledgements
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Revisiting Elasticsearch and the Changes
The Improved Query DSL
Beyond Full Text Search
Data Modeling and Analytics
Improving the User Search Experience
The Index Distribution Architecture
Low-Level Index Control
Elasticsearch Administration
Data Transformation and Federated Search
Improving Performance
Developing Elasticsearch Plugins
Introducing Elastic Stack 5.0
Customer Reviews