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User-Defined Functions (UDFs) play an integral role in enhancing database extensibility and supporting complex queries, yet their usage often imposes performance degradation due to context-switching overheads and optimization boundaries. UDF outlining is the state-of-the-art optimization technique that inherits UDF inlining’s ability to eliminate such constraints while avoiding its drawback of generating complex subqueries that leads to slow execution plans from the database optimizer. This thesis thoroughly examines the design decisions and tradeoffs of PRISM, a UDF optimization module supporting UDF outlining. Through a combination of experimental benchmarking and performance profiling, this study evaluates the impact of adopting PRISM in four modern database systems. The results highlight the applicability of PRISM and the conditions under which it yields substantial performance improvements. Insights gained from this analysis demonstrate the effectiveness of enhancing the execution efficiency of UDFs through the introduction of dedicated PRISM-like UDF optimization modules to database systems.
