Count liczby rekordów w tabeli postgres nie zależny od wielkośc tabeli

SELECT (CASE WHEN reltuples > 0 THEN
        pg_relation_size('table_name')/(8192*relpages/reltuples)
        ELSE 0
        END)::bigint AS estimated_row_count
FROM pg_class
WHERE oid = 'table_name'::regclass;