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https://github.com/ClickHouse/ClickHouse.git
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370 lines
12 KiB
C++
370 lines
12 KiB
C++
#pragma once
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#include <DB/DataStreams/IProfilingBlockInputStream.h>
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#include <DB/Storages/MergeTree/MergeTreeData.h>
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#include <DB/Storages/MergeTree/PKCondition.h>
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#include <DB/Storages/MergeTree/MergeTreeReader.h>
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#include <DB/Storages/MergeTree/MergeTreeReadPool.h>
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namespace DB
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{
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/** Used in conjunction with MergeTreeReadPool, asking it for more work to do and performing whatever reads it is asked
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* to perform. */
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class MergeTreeThreadBlockInputStream : public IProfilingBlockInputStream
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{
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/// "thread" index (there are N threads and each thread is assigned index in interval [0..N-1])
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std::size_t thread;
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public:
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MergeTreeThreadBlockInputStream(
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const std::size_t thread,
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const MergeTreeReadPoolPtr & pool, const std::size_t min_marks_to_read, const std::size_t block_size,
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MergeTreeData & storage, const bool use_uncompressed_cache, const ExpressionActionsPtr & prewhere_actions,
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const String & prewhere_column, const Settings & settings, const Names & virt_column_names)
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: thread{thread}, pool{pool}, block_size_marks{block_size / storage.index_granularity},
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/// round min_marks_to_read up to nearest multiple of block_size expressed in marks
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min_marks_to_read{block_size
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? (min_marks_to_read * storage.index_granularity + block_size - 1)
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/ block_size * block_size / storage.index_granularity
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: min_marks_to_read
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},
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storage{storage}, use_uncompressed_cache{use_uncompressed_cache}, prewhere_actions{prewhere_actions},
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prewhere_column{prewhere_column}, min_bytes_to_use_direct_io{settings.min_bytes_to_use_direct_io},
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max_read_buffer_size{settings.max_read_buffer_size}, virt_column_names{virt_column_names},
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log{&Logger::get("MergeTreeThreadBlockInputStream")}
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{}
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String getName() const override { return "MergeTreeThread"; }
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String getID() const override
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{
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std::stringstream res;
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/// @todo print some meaningful information
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// res << "MergeTreeThread(columns";
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//
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// for (const auto & column : columns)
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// res << ", " << column.name;
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//
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// if (prewhere_actions)
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// res << ", prewhere, " << prewhere_actions->getID();
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//
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// res << ", marks";
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//
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// for (size_t i = 0; i < all_mark_ranges.size(); ++i)
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// res << ", " << all_mark_ranges[i].begin << ", " << all_mark_ranges[i].end;
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//
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// res << ")";
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res << static_cast<const void *>(this);
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return res.str();
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}
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protected:
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/// Будем вызывать progressImpl самостоятельно.
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void progress(const Progress & value) override {}
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Block readImpl() override
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{
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Block res;
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while (!res && !isCancelled())
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{
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if (!task && !getNewTask())
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break;
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res = readFromPart();
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if (res)
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injectVirtualColumns(res);
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if (task->mark_ranges.empty())
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task = {};
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}
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return res;
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}
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private:
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/// Requests read task from MergeTreeReadPool and signals whether it got one
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bool getNewTask()
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{
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task = pool->getTask(min_marks_to_read, thread);
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if (!task)
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{
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/** Закрываем файлы (ещё до уничтожения объекта).
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* Чтобы при создании многих источников, но одновременном чтении только из нескольких,
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* буферы не висели в памяти. */
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reader = {};
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pre_reader = {};
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return false;
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}
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const auto path = storage.getFullPath() + task->data_part->name + '/';
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/// Позволяет пулу уменьшать количество потоков в случае слишком медленных чтений.
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auto profile_callback = [this](ReadBufferFromFileBase::ProfileInfo info) { pool->profileFeedback(info); };
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if (!reader)
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{
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if (use_uncompressed_cache)
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owned_uncompressed_cache = storage.context.getUncompressedCache();
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owned_mark_cache = storage.context.getMarkCache();
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reader = std::make_unique<MergeTreeReader>(
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path, task->data_part, task->columns, owned_uncompressed_cache.get(), owned_mark_cache.get(), true,
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storage, task->mark_ranges, min_bytes_to_use_direct_io, max_read_buffer_size, MergeTreeReader::ValueSizeMap{}, profile_callback);
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if (prewhere_actions)
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pre_reader = std::make_unique<MergeTreeReader>(
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path, task->data_part, task->pre_columns, owned_uncompressed_cache.get(), owned_mark_cache.get(), true,
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storage, task->mark_ranges, min_bytes_to_use_direct_io,
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max_read_buffer_size, MergeTreeReader::ValueSizeMap{}, profile_callback);
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}
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else
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{
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/// retain avg_value_size_hints
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reader = std::make_unique<MergeTreeReader>(
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path, task->data_part, task->columns, owned_uncompressed_cache.get(), owned_mark_cache.get(), true,
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storage, task->mark_ranges, min_bytes_to_use_direct_io, max_read_buffer_size,
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reader->getAvgValueSizeHints(), profile_callback);
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if (prewhere_actions)
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pre_reader = std::make_unique<MergeTreeReader>(
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path, task->data_part, task->pre_columns, owned_uncompressed_cache.get(), owned_mark_cache.get(), true,
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storage, task->mark_ranges, min_bytes_to_use_direct_io,
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max_read_buffer_size, pre_reader->getAvgValueSizeHints(), profile_callback);
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}
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return true;
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}
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Block readFromPart()
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{
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Block res;
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if (prewhere_actions)
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{
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do
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{
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/// Прочитаем полный блок столбцов, нужных для вычисления выражения в PREWHERE.
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size_t space_left = std::max(1LU, block_size_marks);
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MarkRanges ranges_to_read;
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while (!task->mark_ranges.empty() && space_left && !isCancelled())
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{
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auto & range = task->mark_ranges.back();
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size_t marks_to_read = std::min(range.end - range.begin, space_left);
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pre_reader->readRange(range.begin, range.begin + marks_to_read, res);
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ranges_to_read.emplace_back(range.begin, range.begin + marks_to_read);
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space_left -= marks_to_read;
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range.begin += marks_to_read;
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if (range.begin == range.end)
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task->mark_ranges.pop_back();
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}
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/// В случае isCancelled.
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if (!res)
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return res;
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progressImpl({ res.rowsInFirstColumn(), res.bytes() });
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pre_reader->fillMissingColumns(res, task->ordered_names, task->should_reorder);
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/// Вычислим выражение в PREWHERE.
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prewhere_actions->execute(res);
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ColumnPtr column = res.getByName(prewhere_column).column;
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if (task->remove_prewhere_column)
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res.erase(prewhere_column);
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const auto pre_bytes = res.bytes();
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/** Если фильтр - константа (например, написано PREWHERE 1),
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* то либо вернём пустой блок, либо вернём блок без изменений.
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*/
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if (const auto column_const = typeid_cast<const ColumnConstUInt8 *>(column.get()))
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{
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if (!column_const->getData())
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{
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res.clear();
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return res;
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}
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for (const auto & range : ranges_to_read)
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reader->readRange(range.begin, range.end, res);
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progressImpl({ 0, res.bytes() - pre_bytes });
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}
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else if (const auto column_vec = typeid_cast<const ColumnUInt8 *>(column.get()))
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{
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size_t index_granularity = storage.index_granularity;
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const auto & pre_filter = column_vec->getData();
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IColumn::Filter post_filter(pre_filter.size());
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/// Прочитаем в нужных отрезках остальные столбцы и составим для них свой фильтр.
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size_t pre_filter_pos = 0;
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size_t post_filter_pos = 0;
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for (const auto & range : ranges_to_read)
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{
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auto begin = range.begin;
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auto pre_filter_begin_pos = pre_filter_pos;
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for (auto mark = range.begin; mark <= range.end; ++mark)
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{
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UInt8 nonzero = 0;
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if (mark != range.end)
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{
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const size_t limit = std::min(pre_filter.size(), pre_filter_pos + index_granularity);
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for (size_t row = pre_filter_pos; row < limit; ++row)
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nonzero |= pre_filter[row];
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}
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if (!nonzero)
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{
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if (mark > begin)
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{
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memcpy(
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&post_filter[post_filter_pos],
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&pre_filter[pre_filter_begin_pos],
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pre_filter_pos - pre_filter_begin_pos);
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post_filter_pos += pre_filter_pos - pre_filter_begin_pos;
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reader->readRange(begin, mark, res);
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}
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begin = mark + 1;
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pre_filter_begin_pos = std::min(pre_filter_pos + index_granularity, pre_filter.size());
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}
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if (mark < range.end)
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pre_filter_pos = std::min(pre_filter_pos + index_granularity, pre_filter.size());
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}
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}
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if (!post_filter_pos)
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{
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res.clear();
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continue;
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}
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progressImpl({ 0, res.bytes() - pre_bytes });
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post_filter.resize(post_filter_pos);
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/// Отфильтруем столбцы, относящиеся к PREWHERE, используя pre_filter,
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/// остальные столбцы - используя post_filter.
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size_t rows = 0;
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for (const auto i : ext::range(0, res.columns()))
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{
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auto & col = res.getByPosition(i);
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if (col.name == prewhere_column && res.columns() > 1)
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continue;
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col.column =
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col.column->filter(task->column_name_set.count(col.name) ? post_filter : pre_filter, -1);
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rows = col.column->size();
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}
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/// Заменим столбец со значением условия из PREWHERE на константу.
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if (!task->remove_prewhere_column)
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res.getByName(prewhere_column).column = new ColumnConstUInt8{rows, 1};
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}
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else
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throw Exception{
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"Illegal type " + column->getName() + " of column for filter. Must be ColumnUInt8 or ColumnConstUInt8.",
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ErrorCodes::ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER
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};
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if (res)
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reader->fillMissingColumnsAndReorder(res, task->ordered_names);
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}
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while (!task->mark_ranges.empty() && !res && !isCancelled());
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}
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else
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{
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size_t space_left = std::max(1LU, block_size_marks);
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while (!task->mark_ranges.empty() && space_left && !isCancelled())
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{
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auto & range = task->mark_ranges.back();
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const size_t marks_to_read = std::min(range.end - range.begin, space_left);
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reader->readRange(range.begin, range.begin + marks_to_read, res);
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space_left -= marks_to_read;
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range.begin += marks_to_read;
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if (range.begin == range.end)
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task->mark_ranges.pop_back();
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}
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/// В случае isCancelled.
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if (!res)
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return res;
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progressImpl({ res.rowsInFirstColumn(), res.bytes() });
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reader->fillMissingColumns(res, task->ordered_names, task->should_reorder);
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}
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return res;
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}
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void injectVirtualColumns(Block & block)
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{
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const auto rows = block.rowsInFirstColumn();
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/// add virtual columns
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if (!virt_column_names.empty())
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{
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for (const auto & virt_column_name : virt_column_names)
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{
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if (virt_column_name == "_part")
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{
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block.insert(ColumnWithTypeAndName{
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ColumnConst<String>{rows, task->data_part->name}.convertToFullColumn(),
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new DataTypeString,
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virt_column_name
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});
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}
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else if (virt_column_name == "_part_index")
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{
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block.insert(ColumnWithTypeAndName{
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ColumnConst<UInt64>{rows, task->part_index_in_query}.convertToFullColumn(),
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new DataTypeUInt64,
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virt_column_name
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});
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}
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}
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}
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}
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MergeTreeReadPoolPtr pool;
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const std::size_t block_size_marks;
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const std::size_t min_marks_to_read;
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MergeTreeData & storage;
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const bool use_uncompressed_cache;
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ExpressionActionsPtr prewhere_actions;
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const String prewhere_column;
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const std::size_t min_bytes_to_use_direct_io;
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const std::size_t max_read_buffer_size;
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const Names virt_column_names;
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Logger * log;
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using MergeTreeReaderPtr = std::unique_ptr<MergeTreeReader>;
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UncompressedCachePtr owned_uncompressed_cache;
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MarkCachePtr owned_mark_cache;
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MergeTreeReadTaskPtr task;
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MergeTreeReaderPtr reader;
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MergeTreeReaderPtr pre_reader;
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};
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}
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