2018-07-20 10:00:56 +00:00
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#pragma once
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#include <DataStreams/OneBlockInputStream.h>
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#include <DataTypes/DataTypeString.h>
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#include <Storages/ColumnsDescription.h>
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#include <Storages/IStorage.h>
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#include <ext/shared_ptr_helper.h>
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namespace DB
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{
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2018-07-20 15:59:11 +00:00
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2018-07-20 10:00:56 +00:00
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class Context;
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2018-07-20 15:59:11 +00:00
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/** Base class for system tables whose all columns have String type.
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*/
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2018-07-20 10:00:56 +00:00
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template <typename Self>
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2018-07-23 16:10:57 +00:00
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class IStorageSystemOneBlock : public IStorage
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2018-07-20 10:00:56 +00:00
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{
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protected:
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2018-07-24 14:28:56 +00:00
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virtual void fillData(MutableColumns & res_columns, const Context & context, const SelectQueryInfo & query_info) const = 0;
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2018-07-20 10:00:56 +00:00
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public:
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2018-07-23 16:10:57 +00:00
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IStorageSystemOneBlock(const String & name_) : name(name_)
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2018-07-20 10:00:56 +00:00
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{
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2018-07-23 16:10:57 +00:00
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setColumns(ColumnsDescription(Self::getNamesAndTypes()));
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2018-07-20 10:00:56 +00:00
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}
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2019-07-09 15:40:21 +00:00
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std::string getTableName() const override { return name; }
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std::string getDatabaseName() const override { return "system"; }
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2018-07-20 10:00:56 +00:00
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BlockInputStreams read(const Names & column_names,
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2018-07-24 14:28:56 +00:00
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const SelectQueryInfo & query_info,
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const Context & context,
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2018-09-08 11:29:23 +00:00
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QueryProcessingStage::Enum /*processed_stage*/,
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2018-07-20 10:00:56 +00:00
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size_t /*max_block_size*/,
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unsigned /*num_streams*/) override
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{
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check(column_names);
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2018-07-20 15:59:11 +00:00
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Block sample_block = getSampleBlock();
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MutableColumns res_columns = sample_block.cloneEmptyColumns();
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2018-07-24 14:28:56 +00:00
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fillData(res_columns, context, query_info);
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2018-07-20 10:00:56 +00:00
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2018-07-20 15:59:11 +00:00
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return BlockInputStreams(1, std::make_shared<OneBlockInputStream>(sample_block.cloneWithColumns(std::move(res_columns))));
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2018-07-20 10:00:56 +00:00
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}
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private:
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const String name;
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};
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2018-07-20 15:59:11 +00:00
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2018-07-20 10:00:56 +00:00
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}
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