See: http://mediawiki.org/

MediaWiki is one of the largest WikiEngines, originally created for Wikipedia and used by many other wikis. It sits at the opposite end of the complexity spectrum for WabiSabi, which only borrows a subset of the MediaWiki table syntax (and the definition list syntax, in common with most other engines).

MediaWiki is one of the few major WikiEngines using a RelationalDatabase for storage, which it justifies by being optimized for very large wikis.