ARROW-12728: [C++] Implement count_distinct/distinct hash aggregate kernels #10876
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Actually, if we want to keep the |
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Changed to use Take() to assemble the final results instead of Concatenate(). |
bkietz
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Aug 18, 2021
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Overall this looks good, just a few high level comments and nits
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@michalursa what do you think of adding Grouper::Reserve(additional_capacity_hint)?
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The keys here are pairs of [value, group_id] so just having the number of groups doesn't give much of a capacity hint.
bkietz
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Aug 20, 2021
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@lidavidm needs rebase |
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Rebased, thanks for the heads up. |
pitrou
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Aug 25, 2021
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This reuses the Grouper to add kernels for count_distinct and distinct. The implementation for distinct is very simple and not particularly efficient, leveraging Concatenate to build the output list. Neither kernel handles larger-than-memory processing.