Example implementations: Cassandra HBase/Hadoop Data model: { twitter: [ { "derick" : "derickr" }, { "jeremy" : "jmikola } ] } { email: [ { "derick" : "derick@derickrethans.nl" } ] } { sites: [ { "derick" : [ "http://derickrethans.nl", "http://xdebug.org" ] } ] }