Before joining NTU, he was an Assistant professor at Aalborg University, a researcher at Microsoft Research Asia, and a Postdoc at University of Edinburgh. He received his Ph.D. in Computer Science from National University of Singapore in 2004. His research interests include geospatial and textual data management, data mining, context aware recommendation, and mining social networks and social media. His work is published in SIGMOD, VLDB, KDD, WWW, SIGIR, etc. He served as a PC co-chair for E&A track of VLDB'14. He is an Associate Editor for ACM Transactions on Database Systems.