void evaluateMissingDefaults(Block & block, const NamesAndTypesList & required_columns, const ColumnDefaults & column_defaults, const Context & context) { if (column_defaults.empty()) return; ASTPtr default_expr_list = std::make_shared<ASTExpressionList>(); for (const auto & column : required_columns) { if (block.has(column.name)) continue; const auto it = column_defaults.find(column.name); /// expressions must be cloned to prevent modification by the ExpressionAnalyzer if (it != column_defaults.end()) default_expr_list->children.emplace_back( setAlias(it->second.expression->clone(), it->first)); } /// nothing to evaluate if (default_expr_list->children.empty()) return; /** ExpressionAnalyzer eliminates "unused" columns, in order to ensure their safety * we are going to operate on a copy instead of the original block */ Block copy_block{block}; /// evaluate default values for defaulted columns NamesAndTypesList available_columns; for (size_t i = 0, size = block.columns(); i < size; ++i) available_columns.emplace_back(block.getByPosition(i).name, block.getByPosition(i).type); ExpressionAnalyzer{default_expr_list, context, {}, available_columns}.getActions(true)->execute(copy_block); /// move evaluated columns to the original block, materializing them at the same time for (auto & column_name_type : copy_block) { if (ColumnPtr converted = column_name_type.column->convertToFullColumnIfConst()) column_name_type.column = converted; block.insert(std::move(column_name_type)); } }
ASTPtr InterpreterCreateQuery::formatColumns(NamesAndTypesList columns, const NamesAndTypesList & materialized_columns, const NamesAndTypesList & alias_columns, const ColumnDefaults & column_defaults) { columns.insert(std::end(columns), std::begin(materialized_columns), std::end(materialized_columns)); columns.insert(std::end(columns), std::begin(alias_columns), std::end(alias_columns)); auto columns_list = std::make_shared<ASTExpressionList>(); for (const auto & column : columns) { const auto column_declaration = std::make_shared<ASTColumnDeclaration>(); ASTPtr column_declaration_ptr{column_declaration}; column_declaration->name = column.name; StringPtr type_name = std::make_shared<String>(column.type->getName()); auto pos = type_name->data(); const auto end = pos + type_name->size(); ParserIdentifierWithOptionalParameters storage_p; column_declaration->type = parseQuery(storage_p, pos, end, "data type"); column_declaration->type->query_string = type_name; const auto it = column_defaults.find(column.name); if (it != std::end(column_defaults)) { column_declaration->default_specifier = toString(it->second.type); column_declaration->default_expression = it->second.expression->clone(); } columns_list->children.push_back(column_declaration_ptr); } return columns_list; }