From semantic-mediawiki.org

Elasticsearch is a search engine based on the Lucene library. It provides a distributed, multitenant-capable full-text search engine with an HTTP web interface and schema-free JSON documents.

Elasticsearch in Semantic MediaWiki[edit]

Since Semantic MediaWiki 3.0.0Released on 11 October 2018 and compatible with MW 1.27.0 - 1.31.x. Elasticsearch can be used to query data. See the help page on using Elasticsearch for information on how to make use of this.