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55 lines
1.2 KiB
C++
55 lines
1.2 KiB
C++
#pragma once
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#include <Yandex/logger_useful.h>
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#include <DB/Core/SortDescription.h>
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#include <DB/DataStreams/IProfilingBlockInputStream.h>
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namespace DB
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{
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/** Соединяет поток сортированных по отдельности блоков в сортированный целиком поток.
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*/
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class MergeSortingBlockInputStream : public IProfilingBlockInputStream
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{
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public:
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MergeSortingBlockInputStream(BlockInputStreamPtr input_, SortDescription & description_)
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: description(description_), has_been_read(false), log(&Logger::get("MergeSortingBlockInputStream"))
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{
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children.push_back(input_);
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}
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String getName() const { return "MergeSortingBlockInputStream"; }
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String getID() const
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{
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std::stringstream res;
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res << "MergeSorting(" << children.back()->getID();
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for (size_t i = 0; i < description.size(); ++i)
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res << ", " << description[i].getID();
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res << ")";
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return res.str();
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}
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protected:
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Block readImpl();
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private:
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SortDescription description;
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/// Всё было прочитано.
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bool has_been_read;
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Logger * log;
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/** Слить сразу много блоков с помощью priority queue.
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*/
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Block merge(Blocks & blocks);
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};
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}
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