"Jim Nasby" <jim(dot)nasby(at)enterprisedb(dot)com> writes:
> This is on a 8.2.3 database; vacuums started by autovacuum don't get
> their query_start time set.
Hmm. Query_start is actually defined as "time of last client command
receipt", so it's null just like client_addr/port are. Not sure if
there's anything we should put there that's more meaningful than the
backend start time.
regards, tom lane