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From Pinaki Poddar <>
Subject Re: Clustering & ID TableGenerator (OPENJPA_SEQUENCE_TABLE)
Date Thu, 10 Jul 2008 02:23:59 GMT

Are you referring to clustering of databases or clustering of JVM/AppServers?
If it is the former, openjpa-slice module that let a persistent unit be
connected to multiple databases in the same transaction may be of some
relevance. In slice, we designate one database in the cluster as 'master'
for the purpose of ID generation.  

Michael Vorburger-4 wrote:
> Hello,
> How do you do Clustering and ID TableGenerator
> Will this somehow magically work (how?), or will different nodes "step
> on each other's feet" because they'll use the same PK? Can they each use
> different "slices" ?
> If impossible, do you HAVE to use Identify columns or Sequence
> generators in the DB? I thought that was not such a good idea (if you
> have a choice), performance wise, because it requires an extra
> round-trip to the DB to get the PK e.g. to set it as FK. Also
> states that Statement
> Batching won't work with GeneratedType=IDENTITY - so this option doesn't
> seem terribly tempting in order to get ID and clustering happily married
> together. 
> How do people out there do this with OpenJPA?
> Thank you,
> Michael
> _____________________________
> Michael Vorburger, Odyssey Financial Technologies
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