key: $wgDBname:messages, $wgDBname:messages-hash, $wgDBname:messages-status
ex: wikidb:messages, wikidb:messages-hash, wikidb:messages-status
stores: an array where the keys are DB keys and the values are messages
key: $wgDBname:messages, $wgDBname:messages-hash, $wgDBname:messages-status
ex: wikidb:messages, wikidb:messages-hash, wikidb:messages-status
stores: an array where the keys are DB keys and the values are messages