is a search for a short keyword giving no hits?
By default, MediaWiki uses MyISAM’s fulltext matching functionality to allow searching page content. The default settings for this mean that words of less than four characters won’t be indexed, so results won’t be returned for those queries. To alter this behaviour, MySQL needs to be reconfigured to index shorter terms, and MediaWiki’s search index table needs to be repaired, to rebuild the indices. • For help on reconfiguring MySQL, see http://dev.mysql.com/doc/refman/4.1/en/fulltext-fine-tuning.