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42 lines
1.3 KiB
C++
42 lines
1.3 KiB
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 ReadInOrderOptimizer
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{
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public:
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ReadInOrderOptimizer(
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const ASTSelectQuery & query,
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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, UInt64 limit = 0) const;
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private:
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InputOrderInfoPtr getInputOrderImpl(
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const StorageMetadataPtr & metadata_snapshot,
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const SortDescription & description,
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const ManyExpressionActions & actions,
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const ContextPtr & context,
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UInt64 limit) const;
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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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NameToNameMap array_join_result_to_source;
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SortDescription required_sort_description;
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const ASTSelectQuery & query;
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};
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}
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