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304 lines
12 KiB
C++
304 lines
12 KiB
C++
#include <Storages/MergeTree/MergeTreeBlockReadUtils.h>
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#include <Storages/MergeTree/MergeTreeData.h>
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#include <Common/checkStackSize.h>
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#include <Common/typeid_cast.h>
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#include <Columns/ColumnConst.h>
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#include <unordered_set>
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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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extern const int NO_SUCH_COLUMN_IN_TABLE;
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}
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namespace
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{
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/// Columns absent in part may depend on other absent columns so we are
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/// searching all required physical columns recursively. Return true if found at
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/// least one existing (physical) column in part.
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bool injectRequiredColumnsRecursively(
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const String & column_name,
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const ColumnsDescription & storage_columns,
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const MergeTreeData::AlterConversions & alter_conversions,
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const MergeTreeData::DataPartPtr & part,
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Names & columns,
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NameSet & required_columns,
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NameSet & injected_columns)
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{
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/// This is needed to prevent stack overflow in case of cyclic defaults or
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/// huge AST which for some reason was not validated on parsing/interpreter
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/// stages.
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checkStackSize();
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String column_name_in_part = column_name;
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if (alter_conversions.isColumnRenamed(column_name_in_part))
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column_name_in_part = alter_conversions.getColumnOldName(column_name_in_part);
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/// column has files and hence does not require evaluation
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if (storage_columns.hasPhysical(column_name) && part->hasColumnFiles(column_name_in_part, *storage_columns.getPhysical(column_name).type))
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{
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/// ensure each column is added only once
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if (required_columns.count(column_name) == 0)
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{
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columns.emplace_back(column_name);
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required_columns.emplace(column_name);
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injected_columns.emplace(column_name);
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}
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return true;
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}
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/// Column doesn't have default value and don't exist in part
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/// don't need to add to required set.
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const auto column_default = storage_columns.getDefault(column_name);
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if (!column_default)
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return false;
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/// collect identifiers required for evaluation
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IdentifierNameSet identifiers;
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column_default->expression->collectIdentifierNames(identifiers);
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bool result = false;
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for (const auto & identifier : identifiers)
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result |= injectRequiredColumnsRecursively(identifier, storage_columns, alter_conversions, part, columns, required_columns, injected_columns);
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return result;
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}
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}
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NameSet injectRequiredColumns(const MergeTreeData & storage, const StorageMetadataPtr & metadata_snapshot, const MergeTreeData::DataPartPtr & part, Names & columns)
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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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bool have_at_least_one_physical_column = false;
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const auto & storage_columns = metadata_snapshot->getColumns();
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auto alter_conversions = storage.getAlterConversionsForPart(part);
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for (size_t i = 0; i < columns.size(); ++i)
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{
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/// We are going to fetch only physical columns
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if (!storage_columns.hasPhysical(columns[i]))
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throw Exception("There is no physical column " + columns[i] + " in table.", ErrorCodes::NO_SUCH_COLUMN_IN_TABLE);
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have_at_least_one_physical_column |= injectRequiredColumnsRecursively(
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columns[i], storage_columns, alter_conversions,
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part, columns, required_columns, injected_columns);
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}
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/** Add a column of the minimum size.
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* Used in case when no column is needed or files are missing, but at least you need to know number of rows.
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* Adds to the columns.
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*/
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if (!have_at_least_one_physical_column)
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{
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const auto minimum_size_column_name = part->getColumnNameWithMinimumCompressedSize(metadata_snapshot);
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columns.push_back(minimum_size_column_name);
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/// correctly report added column
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injected_columns.insert(columns.back());
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}
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return injected_columns;
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}
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MergeTreeReadTask::MergeTreeReadTask(
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const MergeTreeData::DataPartPtr & data_part_, const MarkRanges & mark_ranges_, const size_t part_index_in_query_,
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const Names & ordered_names_, const NameSet & column_name_set_, const NamesAndTypesList & columns_,
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const NamesAndTypesList & pre_columns_, const bool remove_prewhere_column_, const bool should_reorder_,
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MergeTreeBlockSizePredictorPtr && size_predictor_)
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: data_part{data_part_}, mark_ranges{mark_ranges_}, part_index_in_query{part_index_in_query_},
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ordered_names{ordered_names_}, column_name_set{column_name_set_}, columns{columns_}, pre_columns{pre_columns_},
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remove_prewhere_column{remove_prewhere_column_}, should_reorder{should_reorder_}, size_predictor{std::move(size_predictor_)}
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{
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}
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MergeTreeReadTask::~MergeTreeReadTask() = default;
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MergeTreeBlockSizePredictor::MergeTreeBlockSizePredictor(
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const MergeTreeData::DataPartPtr & data_part_, const Names & columns, const Block & sample_block)
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: data_part(data_part_)
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{
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number_of_rows_in_part = data_part->rows_count;
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/// Initialize with sample block until update won't called.
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initialize(sample_block, {}, columns);
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}
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void MergeTreeBlockSizePredictor::initialize(const Block & sample_block, const Columns & columns, const Names & names, bool from_update)
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{
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fixed_columns_bytes_per_row = 0;
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dynamic_columns_infos.clear();
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std::unordered_set<String> names_set;
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if (!from_update)
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names_set.insert(names.begin(), names.end());
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size_t num_columns = sample_block.columns();
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for (size_t pos = 0; pos < num_columns; ++pos)
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{
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const auto & column_with_type_and_name = sample_block.getByPosition(pos);
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const String & column_name = column_with_type_and_name.name;
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const ColumnPtr & column_data = from_update ? columns[pos]
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: column_with_type_and_name.column;
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if (!from_update && !names_set.count(column_name))
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continue;
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/// At least PREWHERE filter column might be const.
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if (typeid_cast<const ColumnConst *>(column_data.get()))
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continue;
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if (column_data->valuesHaveFixedSize())
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{
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size_t size_of_value = column_data->sizeOfValueIfFixed();
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fixed_columns_bytes_per_row += column_data->sizeOfValueIfFixed();
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max_size_per_row_fixed = std::max<size_t>(max_size_per_row_fixed, size_of_value);
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}
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else
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{
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ColumnInfo info;
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info.name = column_name;
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/// If column isn't fixed and doesn't have checksum, than take first
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ColumnSize column_size = data_part->getColumnSize(
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column_name, *column_with_type_and_name.type);
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info.bytes_per_row_global = column_size.data_uncompressed
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? column_size.data_uncompressed / number_of_rows_in_part
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: column_data->byteSize() / std::max<size_t>(1, column_data->size());
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dynamic_columns_infos.emplace_back(info);
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}
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}
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bytes_per_row_global = fixed_columns_bytes_per_row;
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for (auto & info : dynamic_columns_infos)
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{
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info.bytes_per_row = info.bytes_per_row_global;
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bytes_per_row_global += info.bytes_per_row_global;
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max_size_per_row_dynamic = std::max<double>(max_size_per_row_dynamic, info.bytes_per_row);
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}
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bytes_per_row_current = bytes_per_row_global;
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}
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void MergeTreeBlockSizePredictor::startBlock()
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{
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block_size_bytes = 0;
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block_size_rows = 0;
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for (auto & info : dynamic_columns_infos)
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info.size_bytes = 0;
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}
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/// TODO: add last_read_row_in_part parameter to take into account gaps between adjacent ranges
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void MergeTreeBlockSizePredictor::update(const Block & sample_block, const Columns & columns, size_t num_rows, double decay)
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{
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if (columns.size() != sample_block.columns())
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throw Exception("Inconsistent number of columns passed to MergeTreeBlockSizePredictor. "
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"Have " + toString(sample_block.columns()) + " in sample block "
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"and " + toString(columns.size()) + " columns in list", ErrorCodes::LOGICAL_ERROR);
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if (!is_initialized_in_update)
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{
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/// Reinitialize with read block to update estimation for DEFAULT and MATERIALIZED columns without data.
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initialize(sample_block, columns, {}, true);
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is_initialized_in_update = true;
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}
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if (num_rows < block_size_rows)
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{
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throw Exception("Updated block has less rows (" + toString(num_rows) + ") than previous one (" + toString(block_size_rows) + ")",
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ErrorCodes::LOGICAL_ERROR);
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}
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size_t diff_rows = num_rows - block_size_rows;
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block_size_bytes = num_rows * fixed_columns_bytes_per_row;
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bytes_per_row_current = fixed_columns_bytes_per_row;
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block_size_rows = num_rows;
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/// Make recursive updates for each read row: v_{i+1} = (1 - decay) v_{i} + decay v_{target}
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/// Use sum of geometric sequence formula to update multiple rows: v{n} = (1 - decay)^n v_{0} + (1 - (1 - decay)^n) v_{target}
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/// NOTE: DEFAULT and MATERIALIZED columns without data has inaccurate estimation of v_{target}
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double alpha = std::pow(1. - decay, diff_rows);
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max_size_per_row_dynamic = 0;
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for (auto & info : dynamic_columns_infos)
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{
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size_t new_size = columns[sample_block.getPositionByName(info.name)]->byteSize();
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size_t diff_size = new_size - info.size_bytes;
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double local_bytes_per_row = static_cast<double>(diff_size) / diff_rows;
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info.bytes_per_row = alpha * info.bytes_per_row + (1. - alpha) * local_bytes_per_row;
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info.size_bytes = new_size;
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block_size_bytes += new_size;
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bytes_per_row_current += info.bytes_per_row;
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max_size_per_row_dynamic = std::max<double>(max_size_per_row_dynamic, info.bytes_per_row);
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}
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}
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MergeTreeReadTaskColumns getReadTaskColumns(
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const MergeTreeData & storage,
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const StorageMetadataPtr & metadata_snapshot,
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const MergeTreeData::DataPartPtr & data_part,
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const Names & required_columns,
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const PrewhereInfoPtr & prewhere_info,
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bool check_columns)
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{
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Names column_names = required_columns;
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Names pre_column_names;
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/// inject columns required for defaults evaluation
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bool should_reorder = !injectRequiredColumns(storage, metadata_snapshot, data_part, column_names).empty();
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if (prewhere_info)
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{
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if (prewhere_info->alias_actions)
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pre_column_names = prewhere_info->alias_actions->getRequiredColumns();
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else
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pre_column_names = prewhere_info->prewhere_actions->getRequiredColumns();
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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 auto injected_pre_columns = injectRequiredColumns(storage, metadata_snapshot, data_part, pre_column_names);
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if (!injected_pre_columns.empty())
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should_reorder = true;
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const NameSet pre_name_set(pre_column_names.begin(), pre_column_names.end());
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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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MergeTreeReadTaskColumns result;
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if (check_columns)
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{
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const NamesAndTypesList & physical_columns = metadata_snapshot->getColumns().getAllPhysical();
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result.pre_columns = physical_columns.addTypes(pre_column_names);
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result.columns = physical_columns.addTypes(column_names);
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}
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else
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{
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result.pre_columns = data_part->getColumns().addTypes(pre_column_names);
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result.columns = data_part->getColumns().addTypes(column_names);
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}
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result.should_reorder = should_reorder;
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return result;
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}
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}
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