get table sizes in postgres

postgres_table_sizes.sql

SELECT
   relname as "Table",
   pg_size_pretty(pg_total_relation_size(relid)) As "Size",
   pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) as "External Size"
   FROM pg_catalog.pg_statio_user_tables
   where relname like {{table_name}}
   ORDER BY pg_total_relation_size(relid) DESC;