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Type:
Bug
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Resolution: Fixed
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Priority:
Major - P3
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Affects Version/s: None
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Component/s: None
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None
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Query Execution
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Fully Compatible
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ALL
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QE 2025-09-01
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0
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None
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Here in accumulator_std_dev.cpp when we're merging spilled results, we find the delta from the previous mean and use it to calculate the std dev per the variance algorithm mentioned in the same file which involves squaring delta. The mean is started as 0 so when the first datapoint is very large squaring delta can lead to delta*delta = nan.
I've attached a repro (the pipeline is little weird because I just simplified a fuzzer query).repro_spill.js
- is related to
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SERVER-109325 change agg fuzzer to not run release memory in pipelines with $stdDevPop/Samp
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- Closed
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- related to
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SERVER-42616 $stdDev accumulator can return imprecise results when spilling to disk
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- Backlog
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