Ingo Müller gave a talk at SAP Database Campus Research Seminar

Ingo Müller gave the following talk at SAP Database Campus Research Seminar in Walldorf, Germany:

Multi-Query Execution through SQL Rewriting -- Pay One, Get Hundreds for Free


Optimizing and running multiple queries jointly instead of one by one has been a topic of research for several decades. It allows for more efficient execution because data access or computations needed by multiple queries can be shared and carried out only once. This is the case in applications such as parameter exploration, business reports, and even ad-hoc analytics, in all of which work sharing techniques have been used commercially.

In this talk, I will first review the prior work in this field. Then I will present a recent project from our group that extends existing work sharing techniques, but departs from them in a significant way: While prior approaches implemented dedicated operators or processing engines, we achieve to execute multi-query queries together by rewriting them to a single one expressed again in SQL. This allows applying work sharing techniques on any system with sufficient coverage of the SQL standard and even if work sharing was not originally foreseen by the system designer. We apply our approach to two Query-as-a-Service systems, where we do not only get significant throughput improvements, but can also execute an entire batch of queries for the price of just a single one. Finally, I will present some results on using the same approach on SAP HANA.