Chris (et al.),
Thanks for the reply. I have not replied sooner because I was hoping to get
some more feedback from the list.
>> I have a recently-migrated Pg cluster running 8.4.7 on Red Hat Enterprise
>> Linux Client release 5.7 (Tikanga) in a VMware VM that is logging the
>> subject warning. The application code is considerably old (deployed back
>> in the 7.4 days, I believe) and the message is preceded by a call to
>> select user_write_unlock(), which is a simple wrapper query that calls
>> pg_advisory_unlock(). What are the causes and possible problems and
>> side-effects of receiving such a log warning? Thank you for any
>> assistance you can provide.
Warning: you don't own a lock of type ExclusiveLock
> That means that you didn't have the lock you were trying to release.
> Whether that indicates a critical error or not depends on application
> logic.
The application appears to be functioning without issue, but I still have
some concerns. One possible cause of the warning I considered was having
the VM underlying storage NFS-mounted on a NetApp. Is it possible that
Postgres is not receiving a meaningful response with respect to
ExclusiveLock locking (i.e. unable to really obtain an ExclusiveLock) due to
VM "disk" residing on an NFS mount?
-- Gary Chambers