Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> From what you described, I would not expect many locking problems. Are
> there any other types of queries you run that may cause a lock?
Row locks (SELECT FOR UPDATE/SHARE) are a possible problem, particularly
if this is a pre-8.1 Postgres where exclusive row locks were used for
foreign key constraints.
regards, tom lane