About me

I am a postdoc in Data Systems Group at the University of Waterloo. I am working with Renée J. Miller on data inteligence. I worked with Tamer Özsu on graph data management.

Previously, I was a postdoc at Lyon 1 University, working with Angela Bonifati. I received my PhD in computer science from the University of Clermont Auvergne, advised by Farouk Toumani.

My research focuses analytical query processing in data systems, particularly for relational and graph data. I have worked on efficient processing of relational queries with aggregation functions and graph queries for pathfinding, spanning both batch and stream processing. My recent focus is on data intelligence, with an emphasis on data discovery and query processing over unstructured data.

Preprints & Submissions

• LazyVLM: Neuro-Symbolic Approach to Video Analytics.
  Xiangru Jian, Wei Pang, Zhengyuan Dong, Chao Zhang, M. Tamer Özsu.
  Preprint 2025.

• GRAPHOMNI: A Comprehensive and Extendable Benchmark Framework for Large Language Models on Graph-theoretic Tasks.
  Hao Xu, Xiangru Jian, Xinjian Zhao, Wei Pang, Chao Zhang, Suyuchen Wang, Qixin Zhang, Zhengyuan Dong, Joao Monteiro, Bang Liu, Qiuzhuang Sun, Tianshu Yu.
  Under review 2025.

• Low-Latency Sliding Window Connectivity.
  Chao Zhang, Angela Bonifati, M. Tamer Özsu.
  Preprint 2025.

• Indexing Techniques for Graph Reachability Queries.
  Chao Zhang, Angela Bonifati, M. Tamer Özsu.
  Accepted with minor revision 2025.

• Parallelization of Incremental Aggregations over Sliding Windows.
  Chao Zhang, Reza Akbarinia, Farouk Toumani.
  Revision under review 2025.

Publications

DBLP: Chao Zhang 0045

• Incremental Sliding Window Connectivity over Streaming Graphs.
  Chao Zhang, Angela Bonifati, M. Tamer Özsu.
  VLDB 2024. [Extended version] [Code]

• Sharing Queries with Nonequivalent User-Defined Aggregate Functions.
  Chao Zhang, Farouk Toumani.
  ACM TODS 2024.

• An Overview of Reachability Indexes on Graphs.
  Chao Zhang, Angela Bonifati, M. Tamer Özsu.
  SIGMOD 2023. [Slides (short)] [Slides (full)]

• A Reachability Index for Recursive Label-Concatenated Graph Queries.
  Chao Zhang, Angela Bonifati, Hugo Kapp, Vlad Ioan Haprian, Jean-Pierre Lozi.
  ICDE 2023. [Extended version] [Code] [Slides]

• Efficient Incremental Computation of Aggregations over Sliding Windows.
  Chao Zhang, Reza Akbarinia, Farouk Toumani.
  KDD 2021. [Code]

• SUDAF: Sharing User-Defined Aggregate Functions.
  Chao Zhang, Farouk Toumani, Bastien Doreau.
  ICDE 2020.

• Sharing Computations for User-Defined Aggregate Functions.
  Chao Zhang, Farouk Toumani.
  EDBT 2020.

• Symmetric and Asymmetric Aggregate Functions in Massively Parallel Computing.
  Chao Zhang.
  VLDB 2017 (PhD Workshop).

Presentations

• Towards High-Throughput and Low-Latency Sliding Window Processing over Data Streams.
  • School of Computer Science, University of Guelph, June 18, 2025.
  • School of Information Technology, York University, April 2, 2024.
• Big Graph Processing Systems (with A. Bonifati).
  • MDD 2022 Summer School, Bastia, June 19-23, 2022.
  • eBISS 2022 Summer School, Cesena, July 4-8, 2022.

Service

• PC Member:
  • VLDB: 2026, 2025, 2024, 2023
  • SIGMOD: 2025, 2024, 2022
  • ICDE: 2026
  • ACM SoCC: 2025, 2024, 2023
  • BDA: 2021 (Demo).
• Invited Journal Reviewer:
  • ACM TODS, VLDBJ, IEEE TKDE

Awards

• Best Paper Award in BDA 2021, Francophone Community in Data Management.
• Best PhD Thesis (runner-up) in BDA 2020, Francophone Community in Data Management.
• Full scholarship for the 1st Big Sky Earth training school in DLR, Germany, April 4th-9th, 2016.

Teaching

• CS 348: Introduction to Database Management at the University of Waterloo, Winter 2023.
• Big Data Processing: Apache Spark in Action at the University of Clermont Auvergne, Spring 2022.
• Semantic Web (labs) at the University of Clermont Auvergne, Fall 2021.