ref #9436
Currently EPHEMERAL column requires an explicit default value provided on CREATE TABLE - we can allow implicit default there

else
            throw Exception();
        if (col_decl.comment)
            column.comment = col_decl.comment->as<ASTLiteral &>().value.get<String>();
        if (col_decl.codec)
        {
            if (col_decl.default_specifier == "ALIAS")
                throw Exception{"Cannot specify codec for column type ALIAS", ErrorCodes::BAD_ARGUMENTS};
            column.codec = CompressionCodecFactory::instance().validateCodecAndGetPreprocessedAST(
                col_decl.codec, column.type, sanity_check_compression_codecs, allow_experimental_codecs);
        }
        if (col_decl.ttl)
            column.ttl = col_decl.ttl;
        res.add(std::move(column));
    }
    if (context_->getSettingsRef().flatten_nested)
        res.flattenNested();
    if (res.getAllPhysical().empty())
        throw Exception{"Cannot CREATE table without physical columns", ErrorCodes::EMPTY_LIST_OF_COLUMNS_PASSED};
    return res;
}
ConstraintsDescription InterpreterCreateQuery::getConstraintsDescription(const ASTExpressionList * constraints)
{
    ASTs constraints_data;
    if (constraints)
        for (const auto & constraint : constraints->children)
            constraints_data.push_back(constraint->clone());
    return ConstraintsDescription{constraints_data};
}
InterpreterCreateQuery::TableProperties InterpreterCreateQuery::getTablePropertiesAndNormalizeCreateQuery(ASTCreateQuery & create) const