def build_url_params(system_ram_gb, osm_pbf_gb, append, pbf_filename):
    """Creates the URL parameter string from individual components.

    Parameters
    ------------------------
    system_ram_gb : float
    osm_pbf_gb : float
    append : bool
    pbf_filename : str

    Returns
    ------------------------
    url_params : str
    """
    url_params = f'system_ram_gb={system_ram_gb}'
    url_params += f'&osm_pbf_gb={osm_pbf_gb}'
    url_params += f'&append={append}'
    url_params += f'&pbf_filename={pbf_filename}'
    url_params += f'&pgosm_layer_set=run'
    return url_params