I've been asked on at least three separate occasions lately how to know if changing a particular postgresql.conf item requires a restart, or a reload, of PostgreSQL. Here is my quick and dirty favorite way to answer this question:

-- configs requiring postgresql restart
select name, setting, context
  from pg_settings where context = 'postmaster';

-- configs requiring postgresql reload
select name, setting, context
 from pg_settings where context = 'sighup';