Database Systems

Rethinking Fixpoint Computation

SQL:1999 introduced WITH RECURSIVE—or recursive common table expressions (CTEs)—a true game changer which turned SQL into a Turing-complete programming language. WITH RECURSIVE is powerful and versatile, but proved to be notoriously hard to grasp and master.

In this line of work, we derive new CTE variants from the simple loop-based operational semantics of SQL:1999’s WITH RECURSIVE. In the absence of fixpoint-based semantics and monotonicity restrictions, these CTE variants enable a SQL authoring style that mimics imperative algorithms. This fresh look at CTEs has a beneficial impact on the readability and performance of iterative SQL queries.

Publications

Democratize MATCH_RECOGNIZE!

Louisa Flüchter née Lambrecht • Tim Findling • Samuel Heid • Marcel Knüdeler • Torsten Grust

Proceedings of 51st Int’l Conference on Very Large Databases (VLDB 2025), September 1-5, 2025, London, UK. PVLDB, Volume 18. (To be published.) doi:10.14778/3750601.3750644

BibTeX Citation
@article{lambrecht2025democratize,
  author = {Lambrecht, Louisa and Findling, Tim and Heid, Samuel and Kn\"{u}deler, Marcel and Grust, Torsten},
  title = {{Democratize MATCH_RECOGNIZE!}},
  year = {2025},
  issue_date = {August 2025},
  publisher = {VLDB Endowment},
  volume = {18},
  number = {12},
  issn = {2150-8097},
  url = {https://doi.org/10.14778/3750601.3750644},
  doi = {10.14778/3750601.3750644},
  journal = {Proc. VLDB Endow.},
  month = sep,
  pages = {5251–5254},
  numpages = {4}
}

How DuckDB is USING KEY to Unlock Recursive Query Performance

Björn BambergDenis HirnTorsten Grust

Proceedings of the 2025 ACM SIGMOD International Conference on Management of Data (SIGMOD'25), June 22–27, 2025, Berlin, Germany. doi:10.1145/3722212.3725107

Trampoline-Style Queries for SQL

Louisa Flüchter née LambrechtTorsten Grust • Altan Birler (TUM) • Thomas Neumann (TUM)

CIDR 2025, 15th Conference on Innovative Data Systems Research (CIDR 2025), January 19-22, 2025, Amsterdam, The Netherlands

BibTeX Citation
@inproceedings{lambrecht2025trampoline,
  author    = {Lambrecht, Louisa and Grust, Torsten and Birler, Altan and Neumann, Thomas},
  title     = {{Trampoline-Style Queries for SQL}},
  booktitle = {Proc.\ CIDR},
  address   = {Amsterdam, The Netherlands},
  year      = {2025}
}

A Fix for the Fixation on Fixpoints

Denis HirnTorsten Grust

Proceedings of the 13th Conference on Innovative Data Systems Research (CIDR 2023), Amsterdam, The Netherlands, January 2023.