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107 lines
3.9 KiB
C++
107 lines
3.9 KiB
C++
#pragma once
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#include <ext/shared_ptr_helper.h>
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#include <Common/OptimizedRegularExpression.h>
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#include <Storages/IStorage.h>
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namespace DB
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{
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/** A table that represents the union of an arbitrary number of other tables.
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* All tables must have the same structure.
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*/
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class StorageMerge final : public ext::shared_ptr_helper<StorageMerge>, public IStorage
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{
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friend struct ext::shared_ptr_helper<StorageMerge>;
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public:
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std::string getName() const override { return "Merge"; }
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bool isRemote() const override;
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/// The check is delayed to the read method. It checks the support of the tables used.
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bool supportsSampling() const override { return true; }
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bool supportsPrewhere() const override { return true; }
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bool supportsFinal() const override { return true; }
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bool supportsIndexForIn() const override { return true; }
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bool supportsSubcolumns() const override { return true; }
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QueryProcessingStage::Enum getQueryProcessingStage(const Context &, QueryProcessingStage::Enum /*to_stage*/, SelectQueryInfo &) const override;
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Pipe read(
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const Names & column_names,
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const StorageMetadataPtr & /*metadata_snapshot*/,
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SelectQueryInfo & query_info,
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const Context & context,
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QueryProcessingStage::Enum processed_stage,
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size_t max_block_size,
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unsigned num_streams) override;
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void checkAlterIsPossible(const AlterCommands & commands, const Settings & /* settings */) const override;
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/// you need to add and remove columns in the sub-tables manually
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/// the structure of sub-tables is not checked
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void alter(const AlterCommands & params, const Context & context, TableLockHolder & table_lock_holder) override;
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bool mayBenefitFromIndexForIn(
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const ASTPtr & left_in_operand, const Context & query_context, const StorageMetadataPtr & metadata_snapshot) const override;
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private:
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String source_database;
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std::optional<std::unordered_set<String>> source_tables;
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std::optional<OptimizedRegularExpression> source_table_regexp;
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const Context & global_context;
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using StorageWithLockAndName = std::tuple<StoragePtr, TableLockHolder, String>;
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using StorageListWithLocks = std::list<StorageWithLockAndName>;
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StorageListWithLocks getSelectedTables(const String & query_id, const Settings & settings) const;
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StorageMerge::StorageListWithLocks getSelectedTables(
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const ASTPtr & query, bool has_virtual_column, const String & query_id, const Settings & settings) const;
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template <typename F>
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StoragePtr getFirstTable(F && predicate) const;
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DatabaseTablesIteratorPtr getDatabaseIterator(const Context & context) const;
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NamesAndTypesList getVirtuals() const override;
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ColumnSizeByName getColumnSizes() const override;
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protected:
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StorageMerge(
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const StorageID & table_id_,
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const ColumnsDescription & columns_,
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const String & source_database_,
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const Strings & source_tables_,
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const Context & context_);
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StorageMerge(
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const StorageID & table_id_,
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const ColumnsDescription & columns_,
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const String & source_database_,
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const String & source_table_regexp_,
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const Context & context_);
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Pipe createSources(
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const StorageMetadataPtr & metadata_snapshot,
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SelectQueryInfo & query_info,
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const QueryProcessingStage::Enum & processed_stage,
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const UInt64 max_block_size,
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const Block & header,
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const StorageWithLockAndName & storage_with_lock,
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Names & real_column_names,
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const std::shared_ptr<Context> & modified_context,
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size_t streams_num,
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bool has_table_virtual_column,
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bool concat_streams = false);
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void convertingSourceStream(
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const Block & header, const StorageMetadataPtr & metadata_snapshot,
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const Context & context, ASTPtr & query,
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Pipe & pipe, QueryProcessingStage::Enum processed_stage);
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};
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}
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