Was alerted to an old query lying around in the pg_stat_activity view on a little used server recently. It ha no values for wait_event_type or wait_event and had an idle state value. The query_start value was about two weeks old. Odd, but after verifying it had no pg_lock lookup, I canceled it.
Might there be an infrequent staleness of items that appear in the pg_stat_activity view that is just understood to be there from time to time?