[hibernate-dev] Database with UUID support

[Steve Ebersole]

I am pretty much done with the plumbing for this UUID support.

However...

Another difficulty is the standard database type to which to map UUIDs.
BINARY(16) or CHAR(36) are the most common datatypes used that I have
seen.  I have also seen strategies using NUMERIC and two INTEGER values
(splitting least/most significant bits); the later is not a viable
option though for the built-in support.

I have never used UUIDs as PK values so I am far from an expert here.
>From my understanding the issue is that using the character
representation not only wastes storage but also makes indexing and
joining much slower.  And do all databases support NUMERIC types large
enough?

Personally, I say we use BINARY(16) for the standard support.  WDYT?


On Thu, 2010-05-27 at 07:01 -0500, Steve Ebersole wrote:
> Anyway, the discussion here wrt this UUID project is all about
> generating the UUID value in Java.  The first point is to determine
> whether there is any benefit to relying on the database to generate
> these for us in the cases when they can.
> 
> Secondly there is the question of if we are going to do it in Java then
> what is the correct approach.  Both libraries mentioned here (UUID and
> JUG) use MAC address resolution in building the uuid value.  JUG is
> updating to use java.util.UUID, but relies on native code for
> mac-address-resoltion; UUID use its own UUID class but does not need
> native code for the mac-address-resolution (it uses OS-sniffing and
> system calls).  Heck maybe we offer this as a strategy configurable with
> the Configuration/SessionFactory.
> 
> interface UUIDGenerationStrategy extends Serializable {
>     public int getGenerationVersion(); // informational
>     public UUID generateUUID(SessionImplementor session);
> }
> 
> But first things first...
> 
> Do we use database uuid generation if supported?  Is that itself perhaps
> just a strategy?
> 
> 
> On Thu, 2010-05-27 at 06:12 -0500, Steve Ebersole wrote:
> > The site is not just about the UUID generator project.  He wrote posts
> > on ohter subjects as well.
> > 
> > My point there is more to the maven repo.  How do we reference this?
> >  Are we ending up hosting another artifact?  How do we even contact
> > him to find out?
> > 
> > 
> > 
> > 
> > 
> > -- Sent from my Palm Pre
> > 
> > steve at hibernate.org
> > http://hibernate.org
> > ______________________________________________________________________
> > On May 27, 2010 1:28 AM, Emmanuel Bernard <emmanuel at hibernate.org>
> > wrote: 
> > 
> > To his credit a UUID impl is not a 10 year project plan ;) I would not
> > necessarily consider it abandonware rather than done. 
> > 
> > On 27 mai 2010, at 03:13, Steve Ebersole wrote: 
> > 
> > > and the latest posts on that website are 
> > > from 2007. 
> > 
> > 
> > _______________________________________________ 
> > hibernate-dev mailing list 
> > hibernate-dev at lists.jboss.org 
> > https://lists.jboss.org/mailman/listinfo/hibernate-dev 
> 
> 


-- 
Steve Ebersole <steve at hibernate.org>
http://hibernate.org