Elasticsearch is an open source full text search engine and data analysis tool that was developed in Java, is Apache Lucene-based, and scalable. A huge scale of data is produced at every moment in today's world of information technologies, in social media, in video sharing sites, and in medium and large-sized companies that provide services in communication, health, security, and other areas. Here we are talking about an information/data ocean, and we call this ocean briefly as big data in the world of information technology. An important part of this world of big data is unstructured, scattered, and insignificant when it is in isolation.

For this reason, some requirements such as recording, accessing, analyzing, and processing of data are significant. Like similar search engines, Elasticsearch is one of the tools that have been developed to deal with the problems mentioned previously, which belong to the world of big data.

What should I look for—high efficiency and/or performance—when Elasticsearch is used for the purposes mentioned earlier?

This book will target experienced developers who have used Elasticsearch before and want to extend their knowledge about how to effectively perform Elasticsearch indexing. Therefore, this book assumes that the reader already knows the basic issues and concepts of Elasticsearch. For example, what is Elasticsearch, how to install it, what purposes it serves, and so on. This book in your hand is intended to assist you with technical information and concrete applications about efficient indexing and relevant search result in Elasticsearch. This chapter aims to introduce and discuss the main topics for the purposes mentioned previously. To this end, we will look closely at how to store data by Elasticsearch and try to understand the document storage strategy. The relevant search result is closely related to data analysis. Hence, we will do an introduction to understanding the analysis process. In other chapters of this book, you will find the necessary discussions and examples for a better understanding of the following main issues: