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73 lines
2.2 KiB
C++
73 lines
2.2 KiB
C++
#pragma once
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#include <common/logger_useful.h>
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#include <DataStreams/MergingSortedBlockInputStream.h>
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namespace DB
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{
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/** Merges several sorted streams into one.
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* For each group of consecutive identical values of the primary key (the columns by which the data is sorted),
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* keeps row with max `version` value.
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*/
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class ReplacingSortedBlockInputStream : public MergingSortedBlockInputStream
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{
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public:
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ReplacingSortedBlockInputStream(BlockInputStreams inputs_, const SortDescription & description_,
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const String & version_column_, size_t max_block_size_, WriteBuffer * out_row_sources_buf_ = nullptr)
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: MergingSortedBlockInputStream(inputs_, description_, max_block_size_, 0, out_row_sources_buf_),
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version_column(version_column_)
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{
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}
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String getName() const override { return "ReplacingSorted"; }
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String getID() const override
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{
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std::stringstream res;
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res << "ReplacingSorted(inputs";
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for (size_t i = 0; i < children.size(); ++i)
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res << ", " << children[i]->getID();
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res << ", description";
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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 << ", version_column, " << version_column << ")";
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return res.str();
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}
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protected:
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/// Can return 1 more records than max_block_size.
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Block readImpl() override;
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private:
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String version_column;
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ssize_t version_column_number = -1;
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Logger * log = &Logger::get("ReplacingSortedBlockInputStream");
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/// All data has been read.
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bool finished = false;
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RowRef current_key; /// Primary key of current row.
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RowRef next_key; /// Primary key of next row.
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RowRef selected_row; /// Last row with maximum version for current primary key.
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UInt64 max_version = 0; /// Max version for current primary key.
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PODArray<RowSourcePart> current_row_sources; /// Sources of rows with the current primary key
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void merge(MutableColumns & merged_columns, std::priority_queue<SortCursor> & queue);
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/// Output into result the rows for current primary key.
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void insertRow(MutableColumns & merged_columns, size_t & merged_rows);
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};
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}
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