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32 lines
1.0 KiB
C++
32 lines
1.0 KiB
C++
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#include <Storages/MergeTree/MergeTreeReader.h>
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namespace DB
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{
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MergeTreeRangeReader::MergeTreeRangeReader(
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MergeTreeReader & merge_tree_reader, size_t from_mark, size_t to_mark, size_t index_granularity)
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: merge_tree_reader(merge_tree_reader), current_mark(from_mark), last_mark(to_mark)
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, read_rows_after_current_mark(0), index_granularity(index_granularity), is_reading_started(false)
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{
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}
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bool MergeTreeRangeReader::read(Block & res, size_t max_rows_to_read)
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{
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size_t rows_to_read = (last_mark - current_mark) * index_granularity - read_rows_after_current_mark;
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rows_to_read = std::min(rows_to_read, max_rows_to_read);
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if (rows_to_read == 0)
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return false;
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merge_tree_reader.get().readRange(current_mark, !is_reading_started, rows_to_read, res);
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read_rows_after_current_mark += rows_to_read;
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size_t read_parts = read_rows_after_current_mark / index_granularity;
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current_mark += read_parts;
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read_rows_after_current_mark -= index_granularity * read_parts;
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return current_mark != last_mark;
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}
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}
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