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70 lines
1.5 KiB
C++
70 lines
1.5 KiB
C++
#pragma once
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#include <DB/DataStreams/IProfilingBlockInputStream.h>
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namespace DB
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{
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/** Объединяет несколько источников в один.
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* В отличие от UnionBlockInputStream, делает это последовательно.
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* Блоки разных источников не перемежаются друг с другом.
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*/
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class ConcatBlockInputStream : public IProfilingBlockInputStream
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{
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public:
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ConcatBlockInputStream(BlockInputStreams inputs_)
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{
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children.insert(children.end(), inputs_.begin(), inputs_.end());
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current_stream = children.begin();
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}
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String getName() const override { return "Concat"; }
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String getID() const override
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{
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std::stringstream res;
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res << "Concat(";
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Strings children_ids(children.size());
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for (size_t i = 0; i < children.size(); ++i)
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children_ids[i] = children[i]->getID();
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/// Будем считать, что порядок конкатенации блоков не имеет значения.
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std::sort(children_ids.begin(), children_ids.end());
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for (size_t i = 0; i < children_ids.size(); ++i)
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res << (i == 0 ? "" : ", ") << children_ids[i];
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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() override
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{
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Block res;
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while (current_stream != children.end())
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{
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res = (*current_stream)->read();
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if (res)
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break;
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else
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{
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(*current_stream)->readSuffix();
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++current_stream;
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}
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}
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return res;
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}
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private:
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BlockInputStreams::iterator current_stream;
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};
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}
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