Introduction Big Data Big data has attracted much attention from both academia and industry. o Facebook:750 million users Flickr:6 billion photos Wal-Mart:267 million items/day;4PB data warehouse oSloan Digital Sky Survey:New Mexico telescope captures 200 GB image data/day Science FOURTH PARADIGM data Li (http://cs.nju.edu.cn/lwj) Big Leamning CS.NJU 4/115Introduction Big Data Big data has attracted much attention from both academia and industry. Facebook: 750 million users Flickr: 6 billion photos Wal-Mart: 267 million items/day; 4PB data warehouse Sloan Digital Sky Survey: New Mexico telescope captures 200 GB image data/day Li (http://cs.nju.edu.cn/lwj) Big Learning CS, NJU 4 / 115