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119 lines
3.5 KiB
C++
119 lines
3.5 KiB
C++
#include <DataStreams/ReplacingSortedBlockInputStream.h>
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#include <Columns/ColumnsNumber.h>
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#include <common/logger_useful.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int LOGICAL_ERROR;
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}
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void ReplacingSortedBlockInputStream::insertRow(MutableColumns & merged_columns)
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{
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if (out_row_sources_buf)
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{
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/// true flag value means "skip row"
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current_row_sources[max_pos].setSkipFlag(false);
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out_row_sources_buf->write(reinterpret_cast<const char *>(current_row_sources.data()),
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current_row_sources.size() * sizeof(RowSourcePart));
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current_row_sources.resize(0);
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}
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for (size_t i = 0; i < num_columns; ++i)
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merged_columns[i]->insertFrom(*(*selected_row.columns)[i], selected_row.row_num);
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}
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Block ReplacingSortedBlockInputStream::readImpl()
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{
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if (finished)
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return Block();
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MutableColumns merged_columns;
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init(merged_columns);
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if (has_collation)
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throw Exception("Logical error: " + getName() + " does not support collations", ErrorCodes::LOGICAL_ERROR);
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if (merged_columns.empty())
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return Block();
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merge(merged_columns, queue_without_collation);
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return header.cloneWithColumns(std::move(merged_columns));
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}
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void ReplacingSortedBlockInputStream::merge(MutableColumns & merged_columns, std::priority_queue<SortCursor> & queue)
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{
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MergeStopCondition stop_condition(average_block_sizes, max_block_size);
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/// Take the rows in needed order and put them into `merged_columns` until rows no more than `max_block_size`
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while (!queue.empty())
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{
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SortCursor current = queue.top();
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size_t current_block_granularity = current->rows;
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if (current_key.empty())
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setPrimaryKeyRef(current_key, current);
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setPrimaryKeyRef(next_key, current);
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bool key_differs = next_key != current_key;
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/// if there are enough rows and the last one is calculated completely
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if (key_differs && stop_condition.checkStop())
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return;
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queue.pop();
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if (key_differs)
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{
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/// Write the data for the previous primary key.
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insertRow(merged_columns);
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stop_condition.incrementRowsCountFromGranularity(current_block_granularity);
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selected_row.reset();
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current_key.swap(next_key);
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}
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/// Initially, skip all rows. Unskip last on insert.
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size_t current_pos = current_row_sources.size();
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if (out_row_sources_buf)
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current_row_sources.emplace_back(current.impl->order, true);
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/// A non-strict comparison, since we select the last row for the same version values.
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if (version_column_number == -1
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|| selected_row.empty()
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|| current->all_columns[version_column_number]->compareAt(
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current->pos, selected_row.row_num,
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*(*selected_row.columns)[version_column_number],
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/* nan_direction_hint = */ 1) >= 0)
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{
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max_pos = current_pos;
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setRowRef(selected_row, current);
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}
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if (!current->isLast())
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{
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current->next();
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queue.push(current);
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}
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else
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{
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/// We get the next block from the corresponding source, if there is one.
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fetchNextBlock(current, queue);
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}
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}
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/// We will write the data for the last primary key.
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if (!selected_row.empty())
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insertRow(merged_columns);
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finished = true;
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}
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}
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