#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include namespace DB { namespace ErrorCodes { extern const int LOGICAL_ERROR; extern const int NOT_IMPLEMENTED; extern const int ILLEGAL_PREWHERE; extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH; extern const int SAMPLING_NOT_SUPPORTED; extern const int ALTER_OF_COLUMN_IS_FORBIDDEN; } namespace { void modifySelect(ASTSelectQuery & select, const TreeRewriterResult & rewriter_result) { if (removeJoin(select)) { /// Also remove GROUP BY cause ExpressionAnalyzer would check if it has all aggregate columns but joined columns would be missed. select.setExpression(ASTSelectQuery::Expression::GROUP_BY, {}); /// Replace select list to remove joined columns auto select_list = std::make_shared(); for (const auto & column : rewriter_result.required_source_columns) select_list->children.emplace_back(std::make_shared(column.name)); select.setExpression(ASTSelectQuery::Expression::SELECT, select_list); /// TODO: keep WHERE/PREWHERE. We have to remove joined columns and their expressions but keep others. select.setExpression(ASTSelectQuery::Expression::WHERE, {}); select.setExpression(ASTSelectQuery::Expression::PREWHERE, {}); select.setExpression(ASTSelectQuery::Expression::HAVING, {}); select.setExpression(ASTSelectQuery::Expression::ORDER_BY, {}); } } } StorageMerge::StorageMerge( const StorageID & table_id_, const ColumnsDescription & columns_, const String & source_database_, const Strings & source_tables_, const Context & context_) : IStorage(table_id_) , source_database(source_database_) , source_tables(std::in_place, source_tables_.begin(), source_tables_.end()) , global_context(context_.getGlobalContext()) { StorageInMemoryMetadata storage_metadata; storage_metadata.setColumns(columns_); setInMemoryMetadata(storage_metadata); } StorageMerge::StorageMerge( const StorageID & table_id_, const ColumnsDescription & columns_, const String & source_database_, const String & source_table_regexp_, const Context & context_) : IStorage(table_id_) , source_database(source_database_) , source_table_regexp(source_table_regexp_) , global_context(context_.getGlobalContext()) { StorageInMemoryMetadata storage_metadata; storage_metadata.setColumns(columns_); setInMemoryMetadata(storage_metadata); } template StoragePtr StorageMerge::getFirstTable(F && predicate) const { auto iterator = getDatabaseIterator(global_context); while (iterator->isValid()) { const auto & table = iterator->table(); if (table.get() != this && predicate(table)) return table; iterator->next(); } return {}; } bool StorageMerge::isRemote() const { auto first_remote_table = getFirstTable([](const StoragePtr & table) { return table && table->isRemote(); }); return first_remote_table != nullptr; } bool StorageMerge::mayBenefitFromIndexForIn(const ASTPtr & left_in_operand, const Context & query_context, const StorageMetadataPtr & /*metadata_snapshot*/) const { /// It's beneficial if it is true for at least one table. StorageListWithLocks selected_tables = getSelectedTables( query_context.getCurrentQueryId(), query_context.getSettingsRef()); size_t i = 0; for (const auto & table : selected_tables) { const auto & storage_ptr = std::get<0>(table); auto metadata_snapshot = storage_ptr->getInMemoryMetadataPtr(); if (storage_ptr->mayBenefitFromIndexForIn(left_in_operand, query_context, metadata_snapshot)) return true; ++i; /// For simplicity reasons, check only first ten tables. if (i > 10) break; } return false; } QueryProcessingStage::Enum StorageMerge::getQueryProcessingStage(const Context & context, QueryProcessingStage::Enum to_stage, SelectQueryInfo & query_info) const { ASTPtr modified_query = query_info.query->clone(); auto & modified_select = modified_query->as(); /// In case of JOIN the first stage (which includes JOIN) /// should be done on the initiator always. /// /// Since in case of JOIN query on shards will receive query w/o JOIN (and their columns). /// (see modifySelect()/removeJoin()) /// /// And for this we need to return FetchColumns. if (removeJoin(modified_select)) return QueryProcessingStage::FetchColumns; auto stage_in_source_tables = QueryProcessingStage::FetchColumns; DatabaseTablesIteratorPtr iterator = getDatabaseIterator(context); size_t selected_table_size = 0; while (iterator->isValid()) { const auto & table = iterator->table(); if (table && table.get() != this) { ++selected_table_size; stage_in_source_tables = std::max(stage_in_source_tables, table->getQueryProcessingStage(context, to_stage, query_info)); } iterator->next(); } return selected_table_size == 1 ? stage_in_source_tables : std::min(stage_in_source_tables, QueryProcessingStage::WithMergeableState); } Pipe StorageMerge::read( const Names & column_names, const StorageMetadataPtr & metadata_snapshot, SelectQueryInfo & query_info, const Context & context, QueryProcessingStage::Enum processed_stage, const size_t max_block_size, unsigned num_streams) { Pipes pipes; bool has_table_virtual_column = false; Names real_column_names; real_column_names.reserve(column_names.size()); for (const auto & column_name : column_names) { if (column_name == "_table" && isVirtualColumn(column_name, metadata_snapshot)) has_table_virtual_column = true; else real_column_names.push_back(column_name); } /** Just in case, turn off optimization "transfer to PREWHERE", * since there is no certainty that it works when one of table is MergeTree and other is not. */ auto modified_context = std::make_shared(context); modified_context->setSetting("optimize_move_to_prewhere", false); /// What will be result structure depending on query processed stage in source tables? Block header = getHeaderForProcessingStage(*this, column_names, metadata_snapshot, query_info, context, processed_stage); /** First we make list of selected tables to find out its size. * This is necessary to correctly pass the recommended number of threads to each table. */ StorageListWithLocks selected_tables = getSelectedTables( query_info.query, has_table_virtual_column, context.getCurrentQueryId(), context.getSettingsRef()); if (selected_tables.empty()) /// FIXME: do we support sampling in this case? return createSources( {}, query_info, processed_stage, max_block_size, header, {}, real_column_names, modified_context, 0, has_table_virtual_column); size_t tables_count = selected_tables.size(); Float64 num_streams_multiplier = std::min(unsigned(tables_count), std::max(1U, unsigned(context.getSettingsRef().max_streams_multiplier_for_merge_tables))); num_streams *= num_streams_multiplier; size_t remaining_streams = num_streams; InputOrderInfoPtr input_sorting_info; if (query_info.order_optimizer) { for (auto it = selected_tables.begin(); it != selected_tables.end(); ++it) { auto storage_ptr = std::get<0>(*it); auto storage_metadata_snapshot = storage_ptr->getInMemoryMetadataPtr(); auto current_info = query_info.order_optimizer->getInputOrder(storage_metadata_snapshot, context); if (it == selected_tables.begin()) input_sorting_info = current_info; else if (!current_info || (input_sorting_info && *current_info != *input_sorting_info)) input_sorting_info.reset(); if (!input_sorting_info) break; } query_info.input_order_info = input_sorting_info; } for (const auto & table : selected_tables) { size_t current_need_streams = tables_count >= num_streams ? 1 : (num_streams / tables_count); size_t current_streams = std::min(current_need_streams, remaining_streams); remaining_streams -= current_streams; current_streams = std::max(size_t(1), current_streams); const auto & storage = std::get<0>(table); /// If sampling requested, then check that table supports it. if (query_info.query->as()->sampleSize() && !storage->supportsSampling()) throw Exception("Illegal SAMPLE: table doesn't support sampling", ErrorCodes::SAMPLING_NOT_SUPPORTED); auto storage_metadata_snapshot = storage->getInMemoryMetadataPtr(); auto source_pipe = createSources( storage_metadata_snapshot, query_info, processed_stage, max_block_size, header, table, real_column_names, modified_context, current_streams, has_table_virtual_column); pipes.emplace_back(std::move(source_pipe)); } auto pipe = Pipe::unitePipes(std::move(pipes)); if (!pipe.empty()) // It's possible to have many tables read from merge, resize(num_streams) might open too many files at the same time. // Using narrowPipe instead. narrowPipe(pipe, num_streams); return pipe; } Pipe StorageMerge::createSources( const StorageMetadataPtr & metadata_snapshot, SelectQueryInfo & query_info, const QueryProcessingStage::Enum & processed_stage, const UInt64 max_block_size, const Block & header, const StorageWithLockAndName & storage_with_lock, Names & real_column_names, const std::shared_ptr & modified_context, size_t streams_num, bool has_table_virtual_column, bool concat_streams) { const auto & [storage, struct_lock, table_name] = storage_with_lock; SelectQueryInfo modified_query_info = query_info; modified_query_info.query = query_info.query->clone(); /// Original query could contain JOIN but we need only the first joined table and its columns. auto & modified_select = modified_query_info.query->as(); modifySelect(modified_select, *query_info.syntax_analyzer_result); VirtualColumnUtils::rewriteEntityInAst(modified_query_info.query, "_table", table_name); Pipe pipe; if (!storage) { pipe = QueryPipeline::getPipe(InterpreterSelectQuery( modified_query_info.query, *modified_context, std::make_shared(header), SelectQueryOptions(processed_stage).analyze()).execute().pipeline); pipe.addInterpreterContext(modified_context); return pipe; } auto storage_stage = storage->getQueryProcessingStage(*modified_context, QueryProcessingStage::Complete, modified_query_info); if (processed_stage <= storage_stage) { /// If there are only virtual columns in query, you must request at least one other column. if (real_column_names.empty()) real_column_names.push_back(ExpressionActions::getSmallestColumn(metadata_snapshot->getColumns().getAllPhysical())); pipe = storage->read(real_column_names, metadata_snapshot, modified_query_info, *modified_context, processed_stage, max_block_size, UInt32(streams_num)); } else if (processed_stage > storage_stage) { modified_select.replaceDatabaseAndTable(source_database, table_name); /// Maximum permissible parallelism is streams_num modified_context->setSetting("max_threads", streams_num); modified_context->setSetting("max_streams_to_max_threads_ratio", 1); InterpreterSelectQuery interpreter{modified_query_info.query, *modified_context, SelectQueryOptions(processed_stage)}; pipe = QueryPipeline::getPipe(interpreter.execute().pipeline); /** Materialization is needed, since from distributed storage the constants come materialized. * If you do not do this, different types (Const and non-Const) columns will be produced in different threads, * And this is not allowed, since all code is based on the assumption that in the block stream all types are the same. */ pipe.addSimpleTransform([](const Block & stream_header) { return std::make_shared(stream_header); }); } if (!pipe.empty()) { if (concat_streams && pipe.numOutputPorts() > 1) // It's possible to have many tables read from merge, resize(1) might open too many files at the same time. // Using concat instead. pipe.addTransform(std::make_shared(pipe.getHeader(), pipe.numOutputPorts())); if (has_table_virtual_column) { ColumnWithTypeAndName column; column.name = "_table"; column.type = std::make_shared(); column.column = column.type->createColumnConst(0, Field(table_name)); auto adding_column_dag = ActionsDAG::makeAddingColumnActions(std::move(column)); auto adding_column_actions = std::make_shared(std::move(adding_column_dag)); pipe.addSimpleTransform([&](const Block & stream_header) { return std::make_shared(stream_header, adding_column_actions); }); } /// Subordinary tables could have different but convertible types, like numeric types of different width. /// We must return streams with structure equals to structure of Merge table. convertingSourceStream(header, metadata_snapshot, *modified_context, modified_query_info.query, pipe, processed_stage); pipe.addTableLock(struct_lock); pipe.addStorageHolder(storage); pipe.addInterpreterContext(modified_context); } return pipe; } StorageMerge::StorageListWithLocks StorageMerge::getSelectedTables(const String & query_id, const Settings & settings) const { StorageListWithLocks selected_tables; auto iterator = getDatabaseIterator(global_context); while (iterator->isValid()) { const auto & table = iterator->table(); if (table && table.get() != this) selected_tables.emplace_back( table, table->lockForShare(query_id, settings.lock_acquire_timeout), iterator->name()); iterator->next(); } return selected_tables; } StorageMerge::StorageListWithLocks StorageMerge::getSelectedTables( const ASTPtr & query, bool has_virtual_column, const String & query_id, const Settings & settings) const { StorageListWithLocks selected_tables; DatabaseTablesIteratorPtr iterator = getDatabaseIterator(global_context); auto virtual_column = ColumnString::create(); while (iterator->isValid()) { StoragePtr storage = iterator->table(); if (!storage) continue; if (query && query->as()->prewhere() && !storage->supportsPrewhere()) throw Exception("Storage " + storage->getName() + " doesn't support PREWHERE.", ErrorCodes::ILLEGAL_PREWHERE); if (storage.get() != this) { selected_tables.emplace_back( storage, storage->lockForShare(query_id, settings.lock_acquire_timeout), iterator->name()); virtual_column->insert(iterator->name()); } iterator->next(); } if (has_virtual_column) { Block virtual_columns_block = Block{ColumnWithTypeAndName(std::move(virtual_column), std::make_shared(), "_table")}; VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, global_context); auto values = VirtualColumnUtils::extractSingleValueFromBlock(virtual_columns_block, "_table"); /// Remove unused tables from the list selected_tables.remove_if([&] (const auto & elem) { return values.find(std::get<2>(elem)) == values.end(); }); } return selected_tables; } DatabaseTablesIteratorPtr StorageMerge::getDatabaseIterator(const Context & context) const { try { checkStackSize(); } catch (Exception & e) { e.addMessage("while getting table iterator of Merge table. Maybe caused by two Merge tables that will endlessly try to read each other's data"); throw; } auto database = DatabaseCatalog::instance().getDatabase(source_database); auto table_name_match = [this](const String & table_name_) -> bool { if (source_tables) return source_tables->count(table_name_); else return source_table_regexp->match(table_name_); }; return database->getTablesIterator(context, table_name_match); } void StorageMerge::checkAlterIsPossible(const AlterCommands & commands, const Context & context) const { auto name_deps = getColumnNamesAndReferencedMvMap(context); for (const auto & command : commands) { if (command.type != AlterCommand::Type::ADD_COLUMN && command.type != AlterCommand::Type::MODIFY_COLUMN && command.type != AlterCommand::Type::DROP_COLUMN && command.type != AlterCommand::Type::COMMENT_COLUMN) throw Exception( "Alter of type '" + alterTypeToString(command.type) + "' is not supported by storage " + getName(), ErrorCodes::NOT_IMPLEMENTED); if (command.type == AlterCommand::Type::DROP_COLUMN) { auto deps_mv = name_deps[command.column_name]; if (!deps_mv.empty()) { throw Exception( "Trying to ALTER DROP column " + backQuoteIfNeed(command.column_name) + " which is referenced by materialized view " + toString(deps_mv), ErrorCodes::ALTER_OF_COLUMN_IS_FORBIDDEN); } } } } void StorageMerge::alter( const AlterCommands & params, const Context & context, TableLockHolder &) { auto table_id = getStorageID(); StorageInMemoryMetadata storage_metadata = getInMemoryMetadata(); params.apply(storage_metadata, context); DatabaseCatalog::instance().getDatabase(table_id.database_name)->alterTable(context, table_id, storage_metadata); setInMemoryMetadata(storage_metadata); } void StorageMerge::convertingSourceStream( const Block & header, const StorageMetadataPtr & metadata_snapshot, const Context & context, ASTPtr & query, Pipe & pipe, QueryProcessingStage::Enum processed_stage) { Block before_block_header = pipe.getHeader(); auto convert_actions_dag = ActionsDAG::makeConvertingActions( pipe.getHeader().getColumnsWithTypeAndName(), header.getColumnsWithTypeAndName(), ActionsDAG::MatchColumnsMode::Name); auto convert_actions = std::make_shared(convert_actions_dag); pipe.addSimpleTransform([&](const Block & stream_header) { return std::make_shared(stream_header, convert_actions); }); auto where_expression = query->as()->where(); if (!where_expression) return; for (size_t column_index : ext::range(0, header.columns())) { ColumnWithTypeAndName header_column = header.getByPosition(column_index); ColumnWithTypeAndName before_column = before_block_header.getByName(header_column.name); /// If the processed_stage greater than FetchColumns and the block structure between streams is different. /// the where expression maybe invalid because of convertingBlockInputStream. /// So we need to throw exception. if (!header_column.type->equals(*before_column.type.get()) && processed_stage > QueryProcessingStage::FetchColumns) { NamesAndTypesList source_columns = metadata_snapshot->getSampleBlock().getNamesAndTypesList(); auto virtual_column = *getVirtuals().tryGetByName("_table"); source_columns.emplace_back(NameAndTypePair{virtual_column.name, virtual_column.type}); auto syntax_result = TreeRewriter(context).analyze(where_expression, source_columns); ExpressionActionsPtr actions = ExpressionAnalyzer{where_expression, syntax_result, context}.getActions(false, false); Names required_columns = actions->getRequiredColumns(); for (const auto & required_column : required_columns) { if (required_column == header_column.name) throw Exception("Block structure mismatch in Merge Storage: different types:\n" + before_block_header.dumpStructure() + "\n" + header.dumpStructure(), ErrorCodes::LOGICAL_ERROR); } } } } IStorage::ColumnSizeByName StorageMerge::getColumnSizes() const { auto first_materialize_mysql = getFirstTable([](const StoragePtr & table) { return table && table->getName() == "MaterializeMySQL"; }); if (!first_materialize_mysql) return {}; return first_materialize_mysql->getColumnSizes(); } void registerStorageMerge(StorageFactory & factory) { factory.registerStorage("Merge", [](const StorageFactory::Arguments & args) { /** In query, the name of database is specified as table engine argument which contains source tables, * as well as regex for source-table names. */ ASTs & engine_args = args.engine_args; if (engine_args.size() != 2) throw Exception("Storage Merge requires exactly 2 parameters" " - name of source database and regexp for table names.", ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH); engine_args[0] = evaluateConstantExpressionForDatabaseName(engine_args[0], args.local_context); engine_args[1] = evaluateConstantExpressionAsLiteral(engine_args[1], args.local_context); String source_database = engine_args[0]->as().value.safeGet(); String table_name_regexp = engine_args[1]->as().value.safeGet(); return StorageMerge::create( args.table_id, args.columns, source_database, table_name_regexp, args.context); }); } NamesAndTypesList StorageMerge::getVirtuals() const { NamesAndTypesList virtuals{{"_table", std::make_shared()}}; auto first_table = getFirstTable([](auto && table) { return table; }); if (first_table) { auto table_virtuals = first_table->getVirtuals(); virtuals.insert(virtuals.end(), table_virtuals.begin(), table_virtuals.end()); } return virtuals; } }