On Fri, Jan 14, 2005 at 17:49:42 -0800,
Steve Atkins <steve@blighty.com> wrote:
>
> That's correct, documented behaviour. A serial column is mostly just a
> sequence in disguise. A sequence is guaranteed to give unique,
> increasing values, but in many cases may miss a value (for several
> reasons - in this case because once a sequence value is used, it's
> used, even if the transaction it was used in is rolled back).
Note that the increasing part is only guarenteed within a session,
not accross sessions and only if you haven't changed the sequence
to allow it to roll over.