Emil Briggs <emil(at)baymountain(dot)com> writes:
> When I see the slowdowns there are hundreds of these with no entry for
> relation or database. Any ideas what is being locked in this case?
Per the pg_locks documentation:
Every transaction holds an exclusive lock on its transaction ID for its
entire duration. If one transaction finds it necessary to wait
specifically for another transaction, it does so by attempting to
acquire share lock on the other transaction ID. That will succeed only
when the other transaction terminates and releases its locks.
regards, tom lane