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https://github.com/ClickHouse/ClickHouse.git
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495c6e03aa
* Replace all Context references with std::weak_ptr * Fix shared context captured by value * Fix build * Fix Context with named sessions * Fix copy context * Fix gcc build * Merge with master and fix build * Fix gcc-9 build
34 lines
923 B
C++
34 lines
923 B
C++
#pragma once
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#include <Core/SortDescription.h>
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#include <Storages/MergeTree/MergeTreeData.h>
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#include <Storages/SelectQueryInfo.h>
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namespace DB
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{
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/** Helper class, that can analyze MergeTree order key
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* and required sort description to get their
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* common prefix, which is needed for
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* performing reading in order of PK.
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*/
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class Context;
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class ReadInOrderOptimizer
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{
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public:
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ReadInOrderOptimizer(
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const ManyExpressionActions & elements_actions,
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const SortDescription & required_sort_description,
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const TreeRewriterResultPtr & syntax_result);
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InputOrderInfoPtr getInputOrder(const StorageMetadataPtr & metadata_snapshot, ContextPtr context) const;
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private:
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/// Actions for every element of order expression to analyze functions for monotonicity
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ManyExpressionActions elements_actions;
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NameSet forbidden_columns;
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SortDescription required_sort_description;
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};
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}
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