His research interests are in the areas of databases, Web data management, data mining, and information retrieval. He works on data retrieval/analysis/exploration, ranking and top-k queries, query processing and optimization, Web search, mining, and integration, OLAP, and data warehousing. Chengkai received his Ph.D. degree in Computer Science from the University of Illinois at Urbana-Champaign in 2007, and a M.E. and a B.S. degree in Computer Science from Nanjing University.