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;