Create test table:
`CREATE TABLE test (`id` Int32) ENGINE = MySQL('localhost:3306', '', 'test', 'user', 'pass')`

Attempt insert:
`INSERT INTO test VALUES(1)`

CH sending SQL:
`INSERT INTO ``.`test` (`id`) VALUES (1)`

"``." - sending empty database name in generated SQL

However SELECT statement working with empty database name correctrly

P.S.
This can be useful when working with databases such as sphinx
throw Exception("Table function 'remote': incorrect brace sequence in first argument",
                                ErrorCodes::BAD_ARGUMENTS);
            
            if (last_dot != -1)
            {
                size_t left, right;
                if (description[last_dot - 1] != '.')
                    throw Exception("Table function 'remote': incorrect argument in braces (only one dot): " + description.substr(i, m - i + 1),
                                    ErrorCodes::BAD_ARGUMENTS);
                if (!parseNumber(description, i + 1, last_dot - 1, left))
                    throw Exception("Table function 'remote': incorrect argument in braces (Incorrect left number): "
                                    + description.substr(i, m - i + 1),
                                    ErrorCodes::BAD_ARGUMENTS);
                if (!parseNumber(description, last_dot + 1, m, right))
                    throw Exception("Table function 'remote': incorrect argument in braces (Incorrect right number): "
                                    + description.substr(i, m - i + 1),
                                    ErrorCodes::BAD_ARGUMENTS);
                if (left > right)
                    throw Exception("Table function 'remote': incorrect argument in braces (left number is greater then right): "
                                    + description.substr(i, m - i + 1),
                                    ErrorCodes::BAD_ARGUMENTS);
                if (right - left + 1 >  max_addresses)
                    throw Exception("Table function 'remote': first argument generates too many result addresses",
                        ErrorCodes::BAD_ARGUMENTS);
                bool add_leading_zeroes = false;
                size_t len = last_dot - 1 - (i + 1);
                
                
                if (last_dot - 1 - (i + 1) == m - (last_dot + 1))
                    add_leading_zeroes = true;