QueryBrew: System-Agnostic SQL-to-SQL Query Optimization
Tobias Schmidt, Maximilian Reif, Altan Birler, Thomas Neumann · Proceedings of the VLDB Endowment · 2026
Efficient SQL execution heavily depends on the query optimizer's ability to find efficient query plans. Existing query optimizers differ widely in their capabilities, leading to significant differences in execution complexity across many queries. In this demonstration, we present QueryBrew, a system-agnostic query optimization service that decouples the optimizer from the database engine through SQL-to-SQL rewriting. QueryBrew takes arbitrary SQL queries, refines them using the state-of-the-art Umbra optimizer, and distills the optimized execution plan back into an operator-oriented SQL representation. This allows any target SQL database, such as PostgreSQL, DuckDB, ClickHouse, or SQL Server, to inherit advanced optimization techniques, such as general unnesting, simplification, and adaptive join ordering, without modification. The QueryBrew UI lets users explore and analyze the changes made by Umbra's query optimizer and how they affect execution in the target system. SQL-to-SQL optimization can improve runtimes by more than one order of magnitude for correlated and many-join queries.