On Wed, Jul 15, 2015 at 12:01 AM, Yourfriend <doudou586(at)gmail(dot)com> wrote:
> for example, SO201507_1001, PO201503_1280, etc.
>
> As these IDs would be the most important attribute to the business, so, we
> hope there is no gap for the IDs.
That's a requirement I've heard a number of times before. If you're
relying on a sequence for this purpose, your application is already
broken [1]. UPSERT need not be involved at all.
[1] http://www.varlena.com/GeneralBits/130.php
--
Peter Geoghegan