Sebastian Kornehl <webmaster@sourcebase.org> writes:
> You might be right, I found some pg_prepared_xacts from 2013-05-23. This
> was a test with a XA using application, but the application is already
> offline. There is also no pid available for the given transaction id's.
> Do you have any idea how to close these xa transactions without
> restarting the whole db?
Just use ROLLBACK PREPARED with the ID you see in pg_prepared_xacts.
regards, tom lane