Semantic MediaWiki requires some extensions to the MediaWiki database in order to store the semantic data. The below function ensures that your database is set up properly. The changes made in this step do not affect the rest of the MediaWiki database, and can easily be undone if desired. This setup function can be executed multiple times without doing any harm, but it is needed only once on installation or upgrade.
MediaWiki:Smw smwadmin dbdocu
From Metabolonote