In response to Craig Ringer <craig@xxxxxxxxxxxxxxxxxxxxx>: > Bill Moran wrote: > > > Sounds like you're reinventing message digests ... [snip your comments about why I was wrong about MDs working] > So long as I don't call it "xor encryption" ... sigh. > > > Most of the systems I've seen like this do one of a few things: > > * Start with an arbitrary # like 1000 > > * Prepend the date (pretty common for invoice #s) like 20090501001 > > * Just start with #1 ... I mean, what's the big deal? > > I'm not the one who cares. Alas, I've been given requirements to > satisfy, and one of the major ones is that customer numbers in > particular must be non-sequential (as close to random-looking as > possible) and allocated across a large range. Why not just grab random values for that one, then? Just generate a random value, check to ensure it doesn't already exist ... rinse and repeat if it's a duplicate. I mean, how often is this system adding new customers? Another trick with the invoice #s is to prepend them with a subset of the client ID. You could also use the same technique ... generate a random value, repeat if it already exists ... -- Bill Moran http://www.potentialtech.com http://people.collaborativefusion.com/~wmoran/ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
