Brian Cox <brian.cox@ca.com> writes:
> Actually, they're all deadlocked. The question is why?
Probably because the DROP is trying to acquire exclusive lock on its
target table, and some other transaction already has a read or write
lock on that table, and everything else is queuing up behind the DROP.
It's not a true deadlock that is visible to the database, or else
Postgres would have failed enough of the transactions to remove the
deadlock. Rather, what you've got is some very-long-running transaction
that is still making progress, or else is sitting idle because its
client is neglecting to close it; and everything else is blocked behind
that.
If it is not clear to you exactly who is waiting for what, a look into
the pg_locks view might help.
regards, tom lane
