Function create

src/DataTypes/DataTypeDynamic.cpp:68–102

}

static DataTypePtr create(const ASTPtr & arguments)
{
    if (!arguments || arguments->children.empty())
        return std::make_shared<DataTypeDynamic>();

    if (arguments->children.size() > 1)
        throw Exception(ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH,
                        "Dynamic data type can have only one optional argument - the maximum number of dynamic types in a form 'Dynamic(max_types=N)");


    const auto * argument = arguments->children[0]->as<ASTFunction>();
    if (!argument || argument->name != "equals")
        throw Exception(ErrorCodes::UNEXPECTED_AST_STRUCTURE, "Dynamic data type argument should be in a form 'max_types=N'");

    /// The `equals` function expects exactly two children: an identifier and a literal.
    /// Validate the argument list shape before indexing.
    if (!argument->arguments || argument->arguments->children.size() != 2)
        throw Exception(ErrorCodes::UNEXPECTED_AST_STRUCTURE, "Dynamic data type argument should be in a form 'max_types=N'");

    const auto & identifier_node = argument->arguments->children[0];
    const auto * identifier = identifier_node->as<ASTIdentifier>();
    if (!identifier)
        throw Exception(ErrorCodes::UNEXPECTED_AST_STRUCTURE, "Unexpected Dynamic type argument: {}. Expected expression 'max_types=N'", identifier_node->formatForErrorMessage());

    auto identifier_name = identifier->name();
    if (identifier_name != "max_types")
        throw Exception(ErrorCodes::UNEXPECTED_AST_STRUCTURE, "Unexpected identifier: {}. Dynamic data type argument should be in a form 'max_types=N'", identifier_name);

    auto * literal = argument->arguments->children[1]->as<ASTLiteral>();

    if (!literal || literal->value.getType() != Field::Types::UInt64 || literal->value.safeGet<UInt64>() > ColumnDynamic::MAX_DYNAMIC_TYPES_LIMIT)
        throw Exception(ErrorCodes::UNEXPECTED_AST_STRUCTURE, "'max_types' argument for Dynamic type should be a positive integer between 0 and {}", ColumnDynamic::MAX_DYNAMIC_TYPES_LIMIT);

    return std::make_shared<DataTypeDynamic>(literal->value.safeGet<UInt64>());
}

void registerDataTypeDynamic(DataTypeFactory & factory)
{