Introduction
To efficiently use Elasticsearch, it is very important to understand its design and working.
The goal of this chapter is to give the readers an overview of the basic concepts of Elasticsearch and to be a quick reference for them. It's essential to better understand them to not fall in common pitfalls due to the lack of know-how about Elasticsearch architecture and internals.
The key concepts that we will see in this chapter are node, index, shard, type/mapping, document, and field.
Elasticsearch can be used in several ways such as:
Search engine, which is its main usage
Analytics framework via its powerful aggregation system
Data store, mainly for log
A brief description of the Elasticsearch logic helps the user to improve performance, search quality and decide when and how to optimize the infrastructure to improve scalability and availability. Some details on data replications and base node communication processes are also explained in the upcoming section, Understanding cluster, replication, and sharding.
At the end of this chapter, the protocols used to manage Elasticsearch are also discussed.
