<kynn(at)panix(dot)com> writes:
> The insert statement that is producing this error does not
> include a value for the pkey field in question (this field is of type
> SERIAL). I imagine that somehow the counter associated with this
> field got messed up, so that it is mistakenly generating a value that
> has been used already. How can I straighten it out?
You need to do something like
select setval('seq-name', (select max(col) + 1 from table));
regards, tom lane