Espaço de tabela Postgresql

SELECT 
schemaname
, tablename, pg_size_pretty(size) AS size_pretty,
pg_size_pretty
(total_size) AS total_size_pretty
FROM

(SELECT *, pg_relation_size(schemaname||'.'||tablename) AS size,
pg_total_relation_size
(schemaname||'.'||tablename) AS total_size
FROM pg_tables
where schemaname = 'public') AS TABLES
ORDER BY total_size DESC
;