PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> The parameter could be updated on the fly. However, dynamically updating
> log_hostname did not affect the disconnection log.
This is operating as designed: the host name is captured at connection
time, and the log_disconnection message just repeats it. What you
propose would not be an improvement, because it'd make it impossible
to match up log_disconnections messages with log_connections ones.
regards, tom lane