2017-06-14 10:50:22 +00:00
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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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2017-06-15 17:01:13 +00:00
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: logger(&Poco::Logger::get("MergeTreeRangeReader"))
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, merge_tree_reader(merge_tree_reader), current_mark(from_mark), last_mark(to_mark)
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2017-06-16 20:11:02 +00:00
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, read_rows_after_current_mark(0), index_granularity(index_granularity), seek_to_from_mark(true), is_reading_finished(false)
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2017-06-14 10:50:22 +00:00
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{
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}
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2017-06-16 20:11:02 +00:00
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size_t MergeTreeRangeReader::skipToNextMark()
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2017-06-15 17:01:13 +00:00
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{
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2017-06-20 10:12:20 +00:00
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auto unread_rows_in_current_part = unreadRowsInCurrentGranule();
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2017-06-15 17:01:13 +00:00
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seek_to_from_mark = true;
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++current_mark;
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read_rows_after_current_mark = 0;
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2017-06-16 20:11:02 +00:00
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return unread_rows_in_current_part;
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2017-06-15 17:01:13 +00:00
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}
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2017-06-21 17:19:35 +00:00
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MergeTreeRangeReader MergeTreeRangeReader::getFutureState(size_t rows_to_read) const
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2017-06-15 17:01:13 +00:00
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{
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MergeTreeRangeReader copy = *this;
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2017-06-21 17:19:35 +00:00
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copy.read_rows_after_current_mark += rows_to_read;
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2017-06-15 17:01:13 +00:00
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size_t read_parts = copy.read_rows_after_current_mark / index_granularity;
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copy.current_mark += read_parts;
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copy.read_rows_after_current_mark -= index_granularity * read_parts;
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return copy;
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}
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2017-06-14 10:50:22 +00:00
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2017-06-16 20:11:02 +00:00
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size_t MergeTreeRangeReader::read(Block & res, size_t max_rows_to_read)
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2017-06-14 10:50:22 +00:00
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{
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2017-06-15 17:01:13 +00:00
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size_t rows_to_read = unreadRows();
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2017-06-14 10:50:22 +00:00
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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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2017-06-16 20:11:02 +00:00
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auto read_rows = merge_tree_reader.get().readRange(current_mark, seek_to_from_mark, rows_to_read, res);
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if (!read_rows)
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read_rows = rows_to_read;
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2017-06-15 17:01:13 +00:00
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seek_to_from_mark = false;
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2017-06-14 10:50:22 +00:00
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2017-06-16 20:11:02 +00:00
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read_rows_after_current_mark += read_rows;
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2017-06-14 10:50:22 +00:00
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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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2017-06-16 20:11:02 +00:00
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if (read_rows < rows_to_read || current_mark == last_mark)
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is_reading_finished = true;
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return read_rows;
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2017-06-14 10:50:22 +00:00
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}
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2017-06-15 17:01:13 +00:00
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MergeTreeRangeReader MergeTreeRangeReader::copyForReader(MergeTreeReader & reader)
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{
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MergeTreeRangeReader copy(reader, current_mark, last_mark, index_granularity);
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copy.seek_to_from_mark = seek_to_from_mark;
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copy.read_rows_after_current_mark = read_rows_after_current_mark;
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return copy;
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}
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2017-06-14 10:50:22 +00:00
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}
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