Elasticsearch is a scalable, full-text search and analytics engine based on Apache Lucene. It is Java-based and allows you to store, search, and analyze big volumes of data quickly in near real-time. It can search and index the document files in diverse formats. Lucene is the underlying technology that Elasticsearch uses for extremely fast data retrieval.
As flexible, scalable, and useful as Elasticsearch is, monitoring your cluster can help you ensure that the cluster is appropriately sized and handles all operations efficiently.