select schemaname as table_schema, relname as table_name, pg_size_pretty(pg_total_relation_size(relid)) as total_size, pg_size_pretty(pg_relation_size(relid)) as data_size, pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) as external_size
from pg_catalog.pg_statio_user_tables
order by pg_total_relation_size(relid) desc, pg_relation_size(relid) desc
limit 10;