query
"select
    case when [pk] is not null then 'pk, ' else '' end ||
    case when [created] is not null then 'created, ' else '' end ||
    case when [planet_int] is not null then 'planet_int, ' else '' end ||
    case when [on_earth] is not null then 'on_earth, ' else '' end ||
    case when [state] is not null then 'state, ' else '' end ||
    case when [_city_id] is not null then '_city_id, ' else '' end ||
    case when [_neighborhood] is not null then '_neighborhood, ' else '' end ||
    case when [tags] is not null then 'tags, ' else '' end ||
    case when [complex_array] is not null then 'complex_array, ' else '' end ||
    case when [distinct_some_null] is not null then 'distinct_some_null, ' else '' end ||
    case when [n] is not null then 'n, ' else '' end
  as columns,
  count(*) as num_rows
from
  [facetable]
group by
  columns
order by
  num_rows desc"