Prof. Dr. Tilmann Rabl

About the Talk

We derive new iterative 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 (1) can hold onto as well as forget the results of earlier loop iterations or (2) maintain iteration results in a keyed table, enabling a SQL authoring style that mimics imperative algorithms. We exercise the new variants using a series of examples to demonstrate that this fresh look at CTEs has a beneficial impact on the readability and performance of iterative SQL queries.

About the Speaker

Prof. Torsten Grust is a Professor and the head of the Data Research Group at the University of Tübingen since 2008. Before this, Prof. Grust worked as a professor of Database Systems at the TU Muenchen and TU Clausthal. In 1999, he received his Ph.D. in Computer Science from the University of Konstanz, Germany.

He and his team's research is centered around databases and is mostly concerned about query languages, examples for this are query optimization, rewriting, transformation and compilation. While doing their research they often take concepts from procedural and functional languages and bring them closer to the relational database systems.