Если вам также нужны имена схем:
SELECT cn.nspname AS schema_child, c.relname AS child, pn.nspname AS schema_parent, p.relname AS parent
FROM pg_inherits
JOIN pg_class AS c ON (inhrelid=c.oid)
JOIN pg_class as p ON (inhparent=p.oid)
JOIN pg_namespace pn ON pn.oid = p.relnamespace
JOIN pg_namespace cn ON cn.oid = c.relnamespace
WHERE p.relname = 'your table name' and pn.nspname = 'your schema name'