list of schema with sizes (relative and absolute) in a PostgreSQL database
SELECT schema_name,
pg_size_pretty(sum(table_size)::bigint),
(sum(table_size) / pg_database_size(current_database())) * 100
FROM (
SELECT pg_catalog.pg_namespace.nspname as schema_name,
pg_relation_size(pg_catalog.pg_class.oid) as table_size
FROM pg_catalog.pg_class
JOIN pg_catalog.pg_namespace ON relnamespace = pg_catalog.pg_namespace.oid
) t
GROUP BY schema_name
ORDER BY schema_name