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54 lines
1.4 KiB
C++
54 lines
1.4 KiB
C++
#pragma once
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#include <ext/shared_ptr_helper.h>
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#include <Core/NamesAndTypes.h>
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#include <Storages/IStorage.h>
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#include <DataStreams/NullBlockInputStream.h>
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#include <DataStreams/NullBlockOutputStream.h>
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namespace DB
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{
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/** When writing, does nothing.
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* When reading, returns nothing.
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*/
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class StorageNull : public ext::shared_ptr_helper<StorageNull>, public IStorage
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{
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friend struct ext::shared_ptr_helper<StorageNull>;
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public:
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std::string getName() const override { return "Null"; }
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BlockInputStreams read(
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const Names & column_names,
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const SelectQueryInfo &,
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const Context & /*context*/,
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QueryProcessingStage::Enum /*processing_stage*/,
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size_t,
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unsigned) override
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{
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return { std::make_shared<NullBlockInputStream>(getSampleBlockForColumns(column_names)) };
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}
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BlockOutputStreamPtr write(const ASTPtr &, const Context &) override
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{
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return std::make_shared<NullBlockOutputStream>(getSampleBlock());
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}
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void alter(
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const AlterCommands & params, const Context & context, TableStructureWriteLockHolder & table_lock_holder) override;
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private:
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protected:
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StorageNull(String database_name_, String table_name_, ColumnsDescription columns_description_, ConstraintsDescription constraints_)
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: IStorage({database_name_, table_name_})
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{
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setColumns(std::move(columns_description_));
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setConstraints(std::move(constraints_));
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}
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};
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}
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