Book Image

Elasticsearch Indexing

By : Huseyin Akdogan
Book Image

Elasticsearch Indexing

By: Huseyin Akdogan

Overview of this book

Beginning with an overview of the way ElasticSearch stores data, you’ll begin to extend your knowledge to tackle indexing and mapping, and learn how to configure ElasticSearch to meet your users’ needs. You’ll then find out how to use analysis and analyzers for greater intelligence in how you organize and pull up search results – to guarantee that every search query is met with the relevant results! You’ll explore the anatomy of an ElasticSearch cluster, and learn how to set up configurations that give you optimum availability as well as scalability. Once you’ve learned how these elements work, you’ll find real-world solutions to help you improve indexing performance, as well as tips and guidance on safety so you can back up and restore data. Once you’ve learned each component outlined throughout, you will be confident that you can help to deliver an improved search experience – exactly what modern users demand and expect.
Table of Contents (15 chapters)
Elasticsearch Indexing
About the Author
About the Reviewer

Segments and merging policies

A Lucene index is composed of smaller chunks that are called segments. In other words, a segment is a section of an index. Each segment is a fully independent index. A new segment can be created when a new document is added or, in the automatic refresh process, it occurs every second by default in Elasticsearch. Each segment consumes system resources (that is, memory, CPU cycles, and so on) and, besides, every segment is checked at search time. This means that if there are more segments, they will be searched and there will be more memory usage. For these reasons, increasing the number of segments is a problem. Small segments are copied to the bigger segment to solve this problem, and the copied segments are deleted from the disk. This operation is called segment merging. It is executed as asynchronous and automatically processes in the background while you are indexing and searching. Segment merging operation saves system resources as well as disk space because...