SphinxSearch MediaWiki Extension
www.mediawiki.org/wiki/Extension:SphinxSearch
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
The Sphinx Search Engine seems to promise exactly that; a full text search engine that is both flexible and fast. This extension incorporates the Sphinx engine into MediaWiki to provide a better alternative for searching.