PostgreSQL DB Garbage raito

size.sql

SELECT pg_database_size('notestock') AS db_size -- Any DB Name
     , ROUND(100 * SUM(
           CASE (a.n_live_tup + a.n_dead_tup) WHEN 0 THEN 0 
           ELSE c.relpages * (a.n_dead_tup / (a.n_live_tup + a.n_dead_tup)::numeric) 
           END 
       ) / SUM(c.relpages), 2) AS garbage_raito
FROM pg_class AS c
JOIN pg_stat_all_tables AS a ON(c.oid = a.relid)
WHERE relpages > 0