I would agrre with the objection to the uniqueness if the random generation.
I prefer the own generator, which is database based and allows to build the
PK from different parts - e.g. installation number is included in PK. The
disadvantage is that the generator must be transaction safe - but it is
worth to deal with just in batch operations - for these cases it can return
the range of PKs.
Mark
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Richard
> Kasperowski
> Sent: 26. eervna 2001 17:07
> To: [EMAIL PROTECTED]
> Subject: Re: [JBoss-user] Key generation by random numbers
>
>
> [EMAIL PROTECTED] wrote:
>
> > As a follow-up to the debate on how to get auto-increment primary
> > keys:
> >
> > Is it feasible to use a random number generator to generate primary
> > keys? I don't really need my records to have steadily increasing keys
> > and my number of records will presumably be much smaller than the size
> > of my value space (4 billion? depending on data type for prim-key). So
> > if I do something along the following when making a new record;
> >
> > boolean created = false;
> > do
> > {
> > Long key = generateRandomLong();
> > created = ejb.create(key, contents);
> > }
> > while (!created);
>
>
> One problem with using random numbers is that they're not guaranteed to
> be unique--two calls to generateRandomLong() can return the same value.
> Another problem is that computing the next random number might be
> relatively computationally expensive. I'd say serial numbers are better.
>
> --
> Richard Kasperowski (mailto:[EMAIL PROTECTED])
> Tel: 617-576-1552, Fax: 617-576-2441
> http://www.altisimo.com/
>
>
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