DSG Seminar Series • Adaptive Join Order Optimization using Search Space Linearization

Speaker: Thomas Neumann,

Technische Universität München

(Talk virtually over zoom; please register here -- note: talk will be recorded)

Abstract: 

Join ordering is one of the core problems of query optimization, as differences in join order can affect the execution time of queries by orders of magnitudes. Unfortunately, the problem is NP hard in general, and real-world queries can join hundreds of relations, which makes exact solutions prohibitive expensive. In this talk we show how to tackle the join ordering problem by using a search space linearization technique. This adaptive optimization mechanism allows for a smooth transition from guaranteed optimality to a greedier approach, depending on the size of problem. In practice, a surprisingly large number of queries can be solved optimally or near optimally, with very low optimization times even for hundreds of relations.

Bio: Thomas Neumann is a full professor in the Department of Computer Science at the Technical University of Munich. His research interests are in the areas of database systems, query processing, and query optimization. In 2020, he received the Gottfried Wilhelm Leibniz Prize, which is considered the most important research award in Germany.

Talk video