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From Thomas Mahler <thm...@web.de>
Subject Re: Foreign Key Conflicts in ODMG
Date Fri, 03 Oct 2003 10:19:31 GMT
Hi again Charles,

I checked the CVS log for ObjectEnvelopeTable. But as far as I can tell 
there have been no changes to the reorder logic since 0.9.9.

Charles Anthony wrote:
> Hi,
> 
> I've discovered that if I get ObjectEnvelope.commit() to call reorder
> *twice*, this problem is alleviated.
> 
> 
> The question is, why is this so ? It "feels" a bit like a bubble-sort not
> being done enough times e.g. perhaps we should re-order until there aren't
> any more changes to do... 

By having a short look at the code I think that you could be right. I'm 
not sure that the current algorithm will work correctly to for an 
arbitrary depth of recursive dependencies.

> 
> Why does reorder build a new hashtable of object envelopes ?

AFAICR this was done to avoid ConcurrentModificationExceptions.

> ps. I don't think this is an rc4 specific problem. 

I agree. This issue need some further investigation. Unfortunately I'm 
quite busy with a high priority project and don't have much time left 
for OJB :-(

cheers,
Thomas

> 
> Cheers,
> 
> Charles.
> 
> 
> 
>>-----Original Message-----
>>From: Charles Anthony [mailto:charles.anthony@hpdsoftware.com]
>>Sent: 02 October 2003 09:46
>>To: 'ojb-dev@db.apache.org'
>>Subject: Foreign Key Conflicts in ODMG
>>
>>
>>Hi,
>>
>>Is anyone aware of any changes in RC4 that may have affected 
>>the ordering of
>>objects to be committed in an ODMG transaction ?
>>
>>We're getting a situation where a series of creates and 
>>updates (in the same
>>odmg trx) causes a foreign key violation, because the INSERTS 
>>are being
>>executed in the wrong order.
>>
>>It's really a tricky thing to track down (it's a situation deep in the
>>internals of our app) and quite difficult to build a testcase 
>>for, so I just
>>wondered if anyone knew of anything that might have affected this ?
>>
>>We believe this code was working in rc3 - well, halfway 
>>between rc3 & rc4.
>>
>>Cheers,
>>
>>Charles.
>>
>>
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> 
> 
> 
> This email and any attachments are strictly confidential and are intended
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