http://www.jdon.com/artichect/scalable5.html
http://www.dedecms.com/knowledge/data-base/nosql/2012/0820/8957.html
http://www.ibm.com/developerworks/cn/opensource/os-cn-couchdb/
http://www.infoq.com/cn/news/2012/05/couchdb-or-mysql