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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: Reordering of database operations causes violation of unique constraint
Date Thu, 12 May 2016 14:08:16 GMT
Hi Andrea,

We saw your message to dev@ already, and there was a reply:

https://lists.apache.org/thread.html/Z8c9iuyg8obghec

I guess you haven't seen it as the reply was sent to the list, not to you directly. So now
I am including your address in cc:. 

Now back to your question. Cayenne does operation ordering to satisfy the constraints. But
the graph sort algorithm has a few known limitations. Namely it doesn't know how to order
dependency cycles (e.g. Employee -> Department -> Manager, who is also an employee).
Those have to be resoled manually. There are two solutions:

* Manual two-step commits - helps to resolve real cycles, when there's no valid ordering satisfying
the constraints at all.
* @SortWeight annotation, which forces a certain predefined commit order between two or more
entities. It helps to resolve cases with "virtual" cycles (where Cayenne thinks there's a
cycle, but the actual commit still has a valid operation ordering that satisfies constraints).

Andrus

> On May 12, 2016, at 1:15 AM, Andrea Biasillo <ab@dataloy.com> wrote:
> 
> Hi!
> 
> My name is Andrea Biasillo, I am software architect in Dataloy AS, Bergen
> Norway. In one of our project we use Cayenne as ORM. Unfortunately we are
> facing the same problem reported by this case:
> 
> https://issues.apache.org/jira/browse/CAY-1898
> 
> Is  this case never  been taken in consideration? Is there a solution or at
> least a work-wround?
> 
> Many regards
> 
> -- 
> 
> Andrea Biasillo - Dataloy Systems
> 
> P: +47 55 36 03 00
> 
> M: +4746542580 <%2B47%2055%2036%2003%2000>
> 
> Dataloy Service Desk <http://support.dataloy.com/>
> 
> Dataloy Knowledge Base <http://kb.dataloy.com/>
> 
> Subscribe to the Dataloy Newsletter <http://dataloy-systems.com/?page_id=591>
> 
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> 
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