Fix incorrect result of approx_percentile in window operations#10368
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kagamiori wants to merge 1 commit intofacebookincubator:mainfrom
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Fix incorrect result of approx_percentile in window operations#10368kagamiori wants to merge 1 commit intofacebookincubator:mainfrom
kagamiori wants to merge 1 commit intofacebookincubator:mainfrom
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Summary: approx_percentile(x, percentiles) returns incorrect result in a window operation where a frame that should return non-NULL follows a frame that returns NULL. Before the fix, the window operation returns NULL for both frames. This is because AggregationWindowFunction::computeAggregate() reuses the same result vector across frames. It calls BaseVector::prepareForReuse() before computing the aggregation for a frame. prepareForReuse() doesn't clear the nulls buffer of the vector as it expects the code that reuse the vector to set nulls properly. ApproxPercentileAggregate, however, doesn't set the result rows to be non-null in the code path for array-typed percentiles. This diff fixes this bug by setting the nulls buffer properly. Differential Revision: D59257658
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This pull request was exported from Phabricator. Differential Revision: D59257658 |
Yuhta
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Jul 2, 2024
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This pull request has been merged in f5bfd1e. |
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Conbench analyzed the 1 benchmark run on commit There was 1 benchmark result indicating a performance regression:
The full Conbench report has more details. |
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Summary:
approx_percentile(x, percentiles) returns incorrect result in a window
operation where a frame that should return non-NULL follows a frame
that returns NULL. Before the fix, the window operation returns NULL
for both frames. This is because
AggregationWindowFunction::computeAggregate() reuses the same
result vector across frames. It calls BaseVector::prepareForReuse()
before computing the aggregation for a frame. prepareForReuse()
doesn't clear the nulls buffer of the vector as it expects the code that
reuse the vector to set nulls properly. ApproxPercentileAggregate,
however, doesn't set the result rows to be non-null in the code path
for array-typed percentiles.
This diff fixes this bug by setting the nulls buffer properly.
Differential Revision: D59257658