Terminologies of Elasticsearch | Elasticsearch Tutorial

Cluster: A cluster is a collection of nodes that shares data.

Node: A node is a single server that is part of the cluster, stores the data, and participates in the cluster’s indexing and search capabilities.

Index: An index is a collection of documents with similar characteristics. An index is more equivalent to a schema in RDBMS.

Type: There can be multiple types within an index. For example, an e-commerce application can have used products in one type and new products in another type of the same index. One index can have multiple types of multiple tables in one database.

Document: A document is a basic unit of information that can be indexed. It is like a row in a table.

Shards and Replicas: Elastic Search indexes are divided into multiple pieces called shards, which allows the index to scale horizontally. Elastic Search also allows us to make copies of index shards, which are called replicas.