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394 lines
14 KiB
C++
394 lines
14 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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namespace DB
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{
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/// Для чтения из одного куска. Для чтения сразу из многих, Storage использует сразу много таких объектов.
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class MergeTreeBlockInputStream : public IProfilingBlockInputStream
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{
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public:
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MergeTreeBlockInputStream(const String & path_, /// Путь к куску
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size_t block_size_, Names column_names,
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MergeTreeData & storage_, const MergeTreeData::DataPartPtr & owned_data_part_,
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const MarkRanges & mark_ranges_, bool use_uncompressed_cache_,
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ExpressionActionsPtr prewhere_actions_, String prewhere_column_, bool check_columns,
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size_t min_bytes_to_use_direct_io_, size_t max_read_buffer_size_)
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:
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path(path_), block_size(block_size_),
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storage(storage_), owned_data_part(owned_data_part_),
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part_columns_lock(new Poco::ScopedReadRWLock(owned_data_part->columns_lock)),
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all_mark_ranges(mark_ranges_), remaining_mark_ranges(mark_ranges_),
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use_uncompressed_cache(use_uncompressed_cache_),
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prewhere_actions(prewhere_actions_), prewhere_column(prewhere_column_),
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log(&Logger::get("MergeTreeBlockInputStream")),
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ordered_names{column_names},
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min_bytes_to_use_direct_io(min_bytes_to_use_direct_io_), max_read_buffer_size(max_read_buffer_size_)
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{
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std::reverse(remaining_mark_ranges.begin(), remaining_mark_ranges.end());
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/// inject columns required for defaults evaluation
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const auto injected_columns = injectRequiredColumns(column_names);
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/// insert injected columns into ordered columns list to avoid exception about different block structures
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ordered_names.insert(std::end(ordered_names), std::begin(injected_columns), std::end(injected_columns));
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Names pre_column_names;
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if (prewhere_actions)
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{
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pre_column_names = prewhere_actions->getRequiredColumns();
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injectRequiredColumns(pre_column_names);
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if (pre_column_names.empty())
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pre_column_names.push_back(column_names[0]);
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const NameSet pre_name_set(pre_column_names.begin(), pre_column_names.end());
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/// Если выражение в PREWHERE - не столбец таблицы, не нужно отдавать наружу столбец с ним
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/// (от storage ожидают получить только столбцы таблицы).
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remove_prewhere_column = !pre_name_set.count(prewhere_column);
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Names post_column_names;
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for (const auto & name : column_names)
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if (!pre_name_set.count(name))
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post_column_names.push_back(name);
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column_names = post_column_names;
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}
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/// will be used to distinguish between PREWHERE and WHERE columns when applying filter
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column_name_set = NameSet{column_names.begin(), column_names.end()};
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if (check_columns)
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{
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/// Под owned_data_part->columns_lock проверим, что все запрошенные столбцы в куске того же типа, что в таблице.
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/// Это может быть не так во время ALTER MODIFY.
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if (!pre_column_names.empty())
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storage.check(owned_data_part->columns, pre_column_names);
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if (!column_names.empty())
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storage.check(owned_data_part->columns, column_names);
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pre_columns = storage.getColumnsList().addTypes(pre_column_names);
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columns = storage.getColumnsList().addTypes(column_names);
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}
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else
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{
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pre_columns = owned_data_part->columns.addTypes(pre_column_names);
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columns = owned_data_part->columns.addTypes(column_names);
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}
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/// Оценим общее количество строк - для прогресс-бара.
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size_t total_rows = 0;
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for (const auto & range : all_mark_ranges)
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total_rows += range.end - range.begin;
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total_rows *= storage.index_granularity;
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LOG_TRACE(log, "Reading " << all_mark_ranges.size() << " ranges from part " << owned_data_part->name
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<< ", approx. " << total_rows
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<< (all_mark_ranges.size() > 1
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? ", up to " + toString((all_mark_ranges.back().end - all_mark_ranges.front().begin) * storage.index_granularity)
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: "")
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<< " rows starting from " << all_mark_ranges.front().begin * storage.index_granularity);
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setTotalRowsApprox(total_rows);
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}
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String getName() const override { return "MergeTree"; }
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String getID() const override
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{
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std::stringstream res;
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res << "MergeTree(" << path << ", columns";
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for (const NameAndTypePair & column : columns)
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res << ", " << column.name;
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if (prewhere_actions)
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res << ", prewhere, " << prewhere_actions->getID();
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res << ", marks";
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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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res << ")";
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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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/** Если некоторых запрошенных столбцов нет в куске,
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* то выясняем, какие столбцы может быть необходимо дополнительно прочитать,
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* чтобы можно было вычислить DEFAULT выражение для этих столбцов.
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* Добавляет их в columns.
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*/
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NameSet injectRequiredColumns(Names & columns) const
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{
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NameSet required_columns{std::begin(columns), std::end(columns)};
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NameSet injected_columns;
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for (size_t i = 0; i < columns.size(); ++i)
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{
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const auto & column_name = columns[i];
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/// column has files and hence does not require evaluation
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if (owned_data_part->hasColumnFiles(column_name))
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continue;
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const auto default_it = storage.column_defaults.find(column_name);
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/// columns has no explicit default expression
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if (default_it == std::end(storage.column_defaults))
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continue;
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/// collect identifiers required for evaluation
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IdentifierNameSet identifiers;
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default_it->second.expression->collectIdentifierNames(identifiers);
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for (const auto & identifier : identifiers)
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{
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if (storage.hasColumn(identifier))
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{
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/// ensure each column is added only once
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if (required_columns.count(identifier) == 0)
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{
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columns.emplace_back(identifier);
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required_columns.emplace(identifier);
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injected_columns.emplace(identifier);
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}
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}
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}
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}
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return injected_columns;
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}
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Block readImpl() override
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{
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Block res;
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if (remaining_mark_ranges.empty())
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return res;
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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.reset(new MergeTreeReader(
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path, owned_data_part, columns, owned_uncompressed_cache.get(), owned_mark_cache.get(), storage,
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all_mark_ranges, min_bytes_to_use_direct_io, max_read_buffer_size));
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if (prewhere_actions)
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pre_reader.reset(new MergeTreeReader(
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path, owned_data_part, pre_columns, owned_uncompressed_cache.get(), owned_mark_cache.get(), storage,
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all_mark_ranges, min_bytes_to_use_direct_io, max_read_buffer_size));
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}
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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 / storage.index_granularity);
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MarkRanges ranges_to_read;
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while (!remaining_mark_ranges.empty() && space_left)
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{
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MarkRange & range = remaining_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.push_back(MarkRange(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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remaining_mark_ranges.pop_back();
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}
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progressImpl(Progress(res.rowsInFirstColumn(), res.bytes()));
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pre_reader->fillMissingColumns(res, ordered_names);
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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 (remove_prewhere_column)
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res.erase(prewhere_column);
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size_t 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 (ColumnConstUInt8 * column_const = typeid_cast<ColumnConstUInt8 *>(&*column))
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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 (size_t i = 0; i < ranges_to_read.size(); ++i)
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{
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const MarkRange & range = ranges_to_read[i];
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reader->readRange(range.begin, range.end, res);
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}
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progressImpl(Progress(0, res.bytes() - pre_bytes));
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}
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else if (ColumnUInt8 * column_vec = typeid_cast<ColumnUInt8 *>(&*column))
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{
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size_t index_granularity = storage.index_granularity;
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const IColumn::Filter & 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 (size_t i = 0; i < ranges_to_read.size(); ++i)
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{
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const MarkRange & range = ranges_to_read[i];
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size_t begin = range.begin;
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size_t pre_filter_begin_pos = pre_filter_pos;
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for (size_t 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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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(Progress(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 (size_t i = 0; i < res.columns(); ++i)
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{
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ColumnWithTypeAndName & column = res.getByPosition(i);
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if (column.name == prewhere_column && res.columns() > 1)
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continue;
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column.column = column.column->filter(column_name_set.count(column.name) ? post_filter : pre_filter);
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rows = column.column->size();
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}
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/// Заменим столбец со значением условия из PREWHERE на константу.
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if (!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("Illegal type " + column->getName() + " of column for filter. Must be ColumnUInt8 or ColumnConstUInt8.", ErrorCodes::ILLEGAL_TYPE_OF_COLUMN_FOR_FILTER);
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reader->fillMissingColumnsAndReorder(res, ordered_names);
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}
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while (!remaining_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 / storage.index_granularity);
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while (!remaining_mark_ranges.empty() && space_left)
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{
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MarkRange & range = remaining_mark_ranges.back();
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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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remaining_mark_ranges.pop_back();
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}
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progressImpl(Progress(res.rowsInFirstColumn(), res.bytes()));
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reader->fillMissingColumns(res, ordered_names);
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}
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if (remaining_mark_ranges.empty())
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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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*/
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reader.reset();
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pre_reader.reset();
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part_columns_lock.reset();
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owned_data_part.reset();
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}
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return res;
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}
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private:
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const String path;
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size_t block_size;
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NamesAndTypesList columns;
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NameSet column_name_set;
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NamesAndTypesList pre_columns;
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MergeTreeData & storage;
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MergeTreeData::DataPartPtr owned_data_part; /// Кусок не будет удалён, пока им владеет этот объект.
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std::unique_ptr<Poco::ScopedReadRWLock> part_columns_lock; /// Не дадим изменить список столбцов куска, пока мы из него читаем.
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MarkRanges all_mark_ranges; /// В каких диапазонах засечек читать. В порядке возрастания номеров.
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MarkRanges remaining_mark_ranges; /// В каких диапазонах засечек еще не прочли.
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/// В порядке убывания номеров, чтобы можно было выбрасывать из конца.
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bool use_uncompressed_cache;
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std::unique_ptr<MergeTreeReader> reader;
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std::unique_ptr<MergeTreeReader> pre_reader;
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ExpressionActionsPtr prewhere_actions;
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String prewhere_column;
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bool remove_prewhere_column;
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Logger * log;
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/// column names in specific order as expected by other stages
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Names ordered_names;
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size_t min_bytes_to_use_direct_io;
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size_t max_read_buffer_size;
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UncompressedCachePtr owned_uncompressed_cache;
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MarkCachePtr owned_mark_cache;
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};
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}
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