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Developer publishes benchmark showing GPU database extension 109x slower than native CPU

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A developer maintaining gpudb, a DuckDB extension for running SQL aggregates on NVIDIA CUDA and Apple Silicon Metal, published a benchmark revealing that native DuckDB outperformed the GPU extension by 3x to 109x across whole-query tests on TPC-H workloads. The honest results were included in the v0.2.0 release notes under the heading 'native CPU wins,' acknowledging that the extension did not make full queries faster at that stage. Investigation traced the losses to structural flaws including double-buffering of column data, a global mutex serializing GPU dispatches, and a lack of IEEE-754 double support on Apple GPUs. Writing down the findings forced a clear diagnosis, leading to a v0.3.0 rewrite that replaced the buffer-heavy pipeline with lightweight 24-byte streaming accumulators. The architectural change eliminated the key bottlenecks and brought end-to-end query performance to within 0–20% of native DuckDB.

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