The UDFBench Benchmark for General-purpose UDF Queries

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Abstract

User-defined functions (UDFs) extend the expressiveness of declarative SQL with functional capabilities, but also pose a core bottleneck in query processing due to the impedance mismatch between the UDF and SQL execution environments, and the limitations of the query optimizers to consistently produce good plans for UDF queries. Research and commercial approaches propose remedies for performant UDF query execution ranging from logical optimization and heuristics to physical optimization and compilation techniques. Each work however follows a different path to evaluate their proposed techniques. Despite the practical significance of optimizing UDF queries, UDFs have not been so far the focus of the database benchmarks. In this paper, we present UDFBench, a UDF-centric database benchmark based on real-world schema and data. We identify the core overheads in UDF query execution and design the UDFBench UDFs and queries to enable experimentation with these overheads, alone or in tandem with others. Finally, to showcase the portability and scope of UDFBench, we present an experimental analysis on five popular databases with different characteristics.