In the beginning, XenForo Enhanced Search (XFES) was intended to be a simple drop-in replacement for MySQL full text search, primarily aimed at large forums whose operation would potentially suffer when attempting to search very large database tables.
As a drop-in, XFES only made use of the enhanced search index and speed for the formal search system, but with version 2.2 we are starting to leverage more of the power afforded by the Elasticsearch back-end.
