Add optional HLL for distinct value count to StatisticsBuilder #11928
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@oerling has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator. |
xiaoxmeng
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Dec 26, 2024
| /// 'disableNumDistinct' is true, distinct values will not be counted. | ||
| explicit StatisticsBuilder( | ||
| const StatisticsBuilderOptions& options, | ||
| bool disableNumDistinct = false) |
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Why we want to disable num distinct but options set it? And I don't see it has been used. Thanks!
| } | ||
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| int64_t cardinality() { | ||
| VELOX_CHECK(hll_); |
| } | ||
| } | ||
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| int64_t cardinality() { |
| @@ -93,6 +93,13 @@ void StatisticsBuilder::merge( | |||
| // Merge size | |||
| mergeCount(size_, other.getSize()); | |||
| } | |||
| if (hll_) { | |||
| if (auto* otherBuilder = dynamic_cast<const StatisticsBuilder*>(&other)) { | |||
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Shall we add VELOX NOT NULL check here? We should expect all other statistic builder has the same type?
| @@ -93,6 +93,13 @@ void StatisticsBuilder::merge( | |||
| // Merge size | |||
| mergeCount(size_, other.getSize()); | |||
| } | |||
| if (hll_) { | |||
| if (auto* otherBuilder = dynamic_cast<const StatisticsBuilder*>(&other)) { | |||
| if (otherBuilder->hll_) { | |||
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Similarly shall we check the other build has set hll?
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@oerling has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator. |
xiaoxmeng
reviewed
Dec 26, 2024
| */ | ||
| class StatisticsBuilder : public virtual dwio::common::ColumnStatistics { | ||
| public: | ||
| /// Constructs with 'options'. If 'options' enable count distinct and |
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Remove the comment here.
| @@ -409,7 +444,7 @@ class MapStatisticsBuilder : public StatisticsBuilder, | |||
| MapStatisticsBuilder( | |||
| const Type& type, | |||
| const StatisticsBuilderOptions& options) | |||
| : StatisticsBuilder{options}, | |||
| : StatisticsBuilder{options.withoutNumDistinct()}, | |||
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We probably don't need to disable here?
xiaoxmeng
approved these changes
Dec 26, 2024
Adds an optional HLL counter for distinct values to StatisticsBuilder. This is used in Verax sampling to estimate column cardinalities for scalar types.
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@oerling has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator. |
athmaja-n
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Jan 10, 2025
…ookincubator#11928) Summary: Adds an optional HLL counter for distinct values to StatisticsBuilder. This is used in Verax sampling to estimate column cardinalities for scalar types. Pull Request resolved: facebookincubator#11928 Reviewed By: xiaoxmeng Differential Revision: D67565289 Pulled By: oerling fbshipit-source-id: e5cbe96059a932377a3d977bca816be6ec52e038
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Adds an optional HLL counter for distinct values to StatisticsBuilder. This is used in Verax sampling to estimate column cardinalities for scalar types.