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From "Hans J. Prueller" <hans.pruel...@gmx.net>
Subject AW: AW: AW: Using @GeneratedValue for IDs on already existing tables
Date Tue, 13 Feb 2007 18:06:48 GMT
> Can you tell us your current J2EE vendor, and if possible the generation 
> strategy selected in the vendor deployment descriptor.  If not, can you 
> grab the last 20 pks from one of the tables, we may be able to guess the 
> strategy

One of the reasons why we are migrating is that the current vendors
generation strategy is crap - we regularly get "duplicate PK" SQL exceptions
on our production servers and the vendor developers don't understand
that their PK generation algorithm is not "production ready" or stable yet.

I don't want to make a product down so I don't name it here but the fact is
that we permanently are having stability problems with the CMP engine.

The solution with hi-lo table setting the value to the current max() of the
db values provided by Patrick sounds good - I think I'll give it a try.

thank you!

hans

> -----Urspr√ľngliche Nachricht-----
> Von: Dain Sundstrom [mailto:dain@iq80.com]
> Gesendet: Dienstag, 13. Februar 2007 18:36
> An: open-jpa-dev@incubator.apache.org
> Betreff: Re: AW: AW: Using @GeneratedValue for IDs on already existing
> tables
> 
> Can you tell us your current J2EE vendor, and if possible the
> generation strategy selected in the vendor deployment descriptor.  If
> not,
> can you grab the last 20 pks from one of the tables, we may be able
> to guess the strategy.
> 
> In general, if you vendor is using a UUID, you should able to use a
> OpenJPA UUID without conflicts.  If the vendor is using some sort of
> DB sequence, you should be able to start a new sequence for OpenJPA
> using a much larger starting number.
> 
> -dain
> 
> On Feb 13, 2007, at 9:00 AM, Hans J. Prueller wrote:
> 
> > thanks for this link but this section only describes the different
> > algorithms that are provided to get the generated value - it does
> > not mention the case what happens if we try to save a new persistent
> > entity with a generated PK value that already exists in the DB?
> >
> > I can remember a legacy persistence framework that was able to retry
> > the insert statement with a "second-try generated PK" just for the
> > case
> > the currently generated one has already been inserted by another
> > process.
> >
> > does nobody else have a similar requirement?
> >
> > hans
> >
> >> -----Urspr√ľngliche Nachricht-----
> >> Von: Abe White [mailto:awhite@bea.com]
> >> Gesendet: Dienstag, 13. Februar 2007 17:35
> >> An: open-jpa-dev@incubator.apache.org
> >> Betreff: Re: AW: Using @GeneratedValue for IDs on already existing
> >> tables
> >>
> >>> does openJPA provide the strategy to re-generate another value for
> >>> the PK
> >>> or do we have to manually deal with this case?
> >>
> >> http://incubator.apache.org/openjpa/docs/latest/manual/
> >> manual.html#ref_guide_sequence
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