Search for "burnmulti" in the archives, which is a contrib module to test pg_multixact.
Thanks, got some links. Will give a try and get back.
Merely waiting does not, but more than one lock being acquired on a tuple does cause a multixact to be created. Try SELECT FOR SHARE on two transactions on the same tuple.
Sure. Also what if there are only inserts/updates which transaction have and there are no explicit select queries?
