A cheap & chearful method of generating unique keys is to use the UID
generator that comes standard with the RMI package:
java.rmi.server.UID
You can hack the code to incorporate the machine's IP address too for
uniqueness across clusters.
The chances of a duplicate key are infinitely small.
The only way to gaurantee a globally unique number is for everyone to tap in
to a central UID server - but I don't know of any such thing existing.
Myles
> -----Original Message-----
> From: Jack Ferrod [SMTP:[EMAIL PROTECTED]]
> Sent: 06 February 2001 08:59
> To: [EMAIL PROTECTED]
> Subject: Re: Autonumber primary keys
>
> Why not take the optimistic approach?
>
> Get a some sort of a random primary key that you think has a big chance of
> being unique.
> Try to insert that into the database. If it gets you a Duplicate Key
> Exception, just regenerate the key and try to insert again. If your
> randomizer is good enough, the chance of having to reinsert is very small,
> so most likely this will perform better than most suggested options.
> Also, the outcome will alway be guaranteed to be unique with respect to
> the other records in the database.
>
> JF
>
> On Mon, 5 Feb 2001 21:01:44 -0500, Jay Walters <[EMAIL PROTECTED]>
> wrote:
>
> >I will add my two cents...
> >
> >Consider how important portability between databases is to you before you
> >rule out leveraging the database's ability to generate your keys.
> Sometimes
> >you need it really bad and need to be portable to a database which
> doesn't
> >have this feature, then you need to build the beans. This is
> particularly
> >true if you are building a product. Usually database portability for
> >internal systems turns out to be a red herring. Imagine the operations
> >people writing database independent scripts. Try optimizing an
> application
> >in a portable fashion. I just ported the product from SQL Server to
> Oracle,
> >do I need to test that?
> >
> >The major database vendors have been doing this for a while, and they
> have
> >scalable solutions to the problem.
> >
> >I've also seen some very elegant solutions in terms of very long primary
> >keys which are galacticly unique, sort of like UUIDs. These are very
> nice
> >and will serve you well if there are issues about your company buying
> >another company and your database schemas are 100% compatible. This is
> not
> >to mention how efficient it will be to store these monsters in memory. I
> >know it's cheap, but it's not free. Some nice int's will probably work
> >quite fine.
> >
> >Talk to the DBA. If you don't have a DBA, then God bless you.
> >
> >Cheers
> >Jay Walters
> >
> >> -----Original Message-----
> >> From: Kevin Gaasch [mailto:[EMAIL PROTECTED]]
> >> Sent: Monday, February 05, 2001 2:52 PM
> >> To: [EMAIL PROTECTED]
> >> Subject: Autonumber primary keys
> >>
> >>
> >> I would like to see everyone's suggestions on how to handle
> Automatically
> >> generated primary keys. Utility objects, vendor specific, etc...
> >>
> >>
> >> --------------------------------------------------
> >> Kevin E. Gaasch
> >> Anderson Merchandisers, Inc.
> >> Java Application Development
> >> Lotus Notes Development
> >> [EMAIL PROTECTED]
> >> (806)376-6251 ext. 4819
> >> (800)999-0904 ext. 4819
> >
> >
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