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https://issues.apache.org/jira/browse/OPENJPA-235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12506624
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Kevan Miller commented on OPENJPA-235:
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Reece, afraid access to the tck would still require signing the NDA.

Patrick, afraid I can't really discuss details of the test failures. They 
wouldn't be in a "JPA" test suite. This is why it would be great if we could 
share some of this information more openly. Best (only?) way that I know of is 
by getting access to our TCK.

I'll see if I (or someon else) can generate enough info on the problem...

> SQL reordering to avoid non-nullable foreign key constraint violations
> ----------------------------------------------------------------------
>
>                 Key: OPENJPA-235
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-235
>             Project: OpenJPA
>          Issue Type: Improvement
>          Components: kernel
>            Reporter: Reece Garrett
>            Assignee: Patrick Linskey
>             Fix For: 0.9.8
>
>         Attachments: merge-detached.patch, 
> merge-multigen-collection-testcase.zip, openjpa-235-test.jar, 
> openjpa-235-test1.jar, openjpa-235-test2.zip, sqlreorder.patch, 
> sqlReorder2.patch, sqlReorderTests.patch
>
>
> OpenJPA does not do any SQL statement re-ordering in order to resolve foreign 
> key constraints. Instead, objects are always inserted in the order in which 
> the user persists the instances.  When you persist in an order that would 
> violate foreign key constraints, OpenJPA attempts to insert null and then 
> update the foreign key value in a separate statement. If you use non-nullable 
> constraints, though, you must persist your objects in the correct order.
> This improvement re-orders SQL statements as follows:
> 1. First, all insert statements execute. Inserts which have foreign keys with 
> non-nullable constraints execute AFTER the foreign keys which they depend on 
> have been inserted since no deferred update is possible.
> 2. Next, all update statements execute. No reordering is necessary.
> 3.  Finally, all delete statements execute. Like inserts, deletes execute in 
> an order which does not violate non-nullable foreign key constraints.
> If a circular foreign key reference is found during the re-ordering process 
> then re-ordering halts and the remaining unordered statements are left as is. 
> There is nothing that can be done about the circular reference (other than 
> fixing the schema) and the resulting SQL statements will not succeed.
> The net effect is that users do not need to worry about the persistence order 
> of their objects regardless of non-nullable foreign key constraints. The only 
> class modified was 
> org.apache.openjpa.jdbc.kernel.OperationOrderUpdateManager. I have included a 
> patch which includes my modifications to OperationOrderUpdateManager and test 
> cases. The test cases I have provided fail on the current trunk but pass with 
> my modifications. I have also verified that I did not break anything by using 
> maven to run all test cases with my modifications in place.

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