postgres tables sorted by size

tables_by_size.sql

SELECT
    nspname || '.' || relname AS "relation",
    pg_size_pretty(pg_relation_size(C.oid)) AS "size"
FROM
    pg_class C
    LEFT JOIN
    pg_namespace N ON (N.oid = C.relnamespace)
WHERE
    nspname NOT IN ('pg_catalog', 'information_schema')
ORDER BY
    pg_relation_size(C.oid)
    DESC LIMIT 20;