Top 10 count distinct values in a column

tally.sql

/*
  Top 10 count distinct values in a column
  eg */ select * from _meta (
    '{app_public}',
    '{data_report_session,data_raw_session,data_report}'),
    _tally(_schema,_relname,_column);/*
*/
create function _tally(_schema name,_relname name,_column name)
  returns table (_tally json) as $function_tally$
    select xmltable.* from (select query_to_xml(format($$
      select json_object_agg(coalesce(%3$I::text,'null'), count) as _tally
        from (
          select %3$I, count(*) 
          from %1$I.%2$I group by %3$I order by 2 desc
          limit 10) c
    $$,_schema,_relname,_column),false,false,'')) q,
    xmltable('//table/row' passing query_to_xml columns _tally json)
$function_tally$ language sql stable;