On Thu, Apr 07, 2005 at 11:27:41PM -0400, Sven Willenberger wrote: > > > David Fetter presumably uttered the following on 04/07/05 20:16: > >On Thu, Apr 07, 2005 at 07:59:52PM -0400, Matthew Terenzio wrote: > > > >>I'm noticing that a sequence is advancing even if the insertion > >>fails. Is this weird or expected? > > > > > >It's expected. Sequences are guaranteed to generate unique IDs. > >These happen to be an increasing sequence of integers, but there is > >no attempt to make this a gap-free sequence, and your apps should > >not depend on the actual value of said ID. > > I assume by "not depend on the actual value" that one should not > assume that the next value will be one increment higher than the > current highest value in the table; Yes. > because it is guaranteed to be unique, I would think it to be an > excellent way to assign a customer id, for example, which can then > be referenced (foreign key, etc) by other tables after a new record > is added. It's designed for just that purpose :) > Unless there is some other reason one should not use a sequence > value as any type of identifier? Relational purists sometimes insist that artificial keys cause more problems than they solve, but I'm not in that camp most of the time. Cheers, D -- David Fetter david@xxxxxxxxxx http://fetter.org/ phone: +1 510 893 6100 mobile: +1 415 235 3778 Remember to vote! ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
