Qichen Wang

I am currently a postdoc at EPFL, working with Professor Christoph Koch. I am also a Research Assistant Professor (on leave) in Department of Computer Science at Hong Kong Baptist University. I received my PhD degree from the Department of Computer Science and Technology at Hong Kong University of Science and Technology, supervised by Professor Ke Yi. Before that, I received my Bachelor’s Degree in Engineering from the Computer Science Department at Zhejiang University. During Aug. 2016 to Jan. 2017, I was a research intern in the Department of Systems Engineering and Engineering Management, The Chinese University of Hong Kong, supervised by Professor Hong Cheng and Professor Jeffrey Xu Yu. I also worked as a research intern at Alibaba, DAMO Academy from June 2019 to Oct. 2019.

Looking for Research Assistants, PhD Students, and Postdoc Research Fellows. Please find the following post and feel free to email me your CV and related materials.

Research interest

Database Theory and Algorithms; Streaming Processing; Distributed and Parallel Computing.

Selected Publications

In publications marked with ‘**’, authors are ordered alphabetically, as a convention of theory papers. In the other publications, authors are ordered by contribution.

Conference papers

• Towards Update-Dependent Analysis of Query Maintenance. **
  Xiao Hu and Qichen Wang.
  ACM Symposium on Principles of Database Systems (PODS), June 2025.

• Yannakakis+: Practical Acyclic Query Evaluation with Theoretical Guarantees.
  Qichen Wang, Bingnan Chen, Binyang Dai, Ke Yi, Feifei Li and Liang Lin.
  ACM SIGMOD International Conference on Management of Data (SIGMOD), June 2025.

• Relational Algorithms for Top-k Query Evaluation.
  Qichen Wang, Qiyao Luo and Yilei Wang.
  ACM SIGMOD International Conference on Management of Data (SIGMOD), June 2024.

• FedKNN: Secure Federated k-Nearest Neighbor Search.
  Xinyi Zhang, Qichen Wang, Cheng Xu, Yun Peng and Jianliang Xu.
  ACM SIGMOD International Conference on Management of Data (SIGMOD), June 2024.

• Computing the Difference of Conjunctive Queries Efficiently. **
  Xiao Hu and Qichen Wang.
  ACM SIGMOD International Conference on Mangement of Data (SIGMOD), June 2023.

• Change Propagation without Joins.
  Qichen Wang, Xiao Hu, Binyang Dai and Ke Yi.
  International Conference on Very Large Data Bases (VLDB), August 2023
  

• Conjunctive Queries with Comparisons.
  Qichen Wang and Ke Yi.
  ACM SIGMOD International Conference on Management of Data (SIGMOD), June 2022.
  (Selected as the ACM SIGMOD Best Paper Honorable Mention)

• Maintaining Acyclic Foreign-Key Joins Under Updates.
  Qichen Wang and Ke Yi.
  ACM SIGMOD International Conference on Management of Data (SIGMOD), June 2020.

• Efficient Computation of a Near-Maximum Independent Set over Evolving Graphs.
  Weiguo Zheng, Qichen Wang, Jeffrey Xu Yu, Hong Cheng, and Lei Zou.
  IEEE International Conference on Data Engineering (ICDE), April 2018.

Demo papers

• SparkSQL+: Next-generation Query Planning over Spark.
  Binyang Dai, Qichen Wang, and Ke Yi.
  ACM SIGMOD International Conference on Management of Data (SIGMOD), June 2023. System demonstration.

• Cquirrel: Continuous Query Processing over Acyclic Relational Schemas.
  Qichen Wang, Chaoqi Zhang, Danish Alsayed, Ke Yi, Bin Wu, Feifei Li, and Chaoqun Zhan.
  International Conference on Very Large Data Bases (VLDB), August 2021. System demonstration.
  

Journal papers

• Conjunctive Queries with Comparisons. [extended abstract]
  Qichen Wang and Ke Yi.
  SIGMOD Record, March 2023.
  (Special issue on the 2022 ACM SIGMOD Research Highlight Award.)

Patent

• Data processing method and device, program product, and storage medium, CN113448969B

Selected Awards

• ACM SIGMOD Research Highlight Award, 2022, ACM SIGMOD

• HKUST CSE Best PhD Dissertation Award Honorable Mention, 2022, HKUST

• ACM SIGMOD Best Paper Honorable Mention award, 2022, ACM SIGMOD

• RedBird Academic Excellence Award for PhD Student, 2022, HKUST

• Postgraduate Studentship, 2017-2021, HKUST

• Scholarship for Elite Students in Basic Science, 2013-2016, Zhejiang University

Services

• PC Member: SIGMOD 2026, CIKM 2025, VLDB 2024, CCS 2024, CIKM 2024
• Journal Review Board: ACM Transactions On Database Systems (TODS)
• Journal Reviewer / Referee: IEEE Transactions on Dependable and Secure Computing (TDSC)
• External Reviewer: PODS 2024, VLDB 2023, SIGMOD 2019-2023, ICDT 2019