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https://issues.apache.org/jira/browse/OPENJPA-235?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David Ezzio updated OPENJPA-235:
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Fix Version/s: 1.1.1
Merged fix to 1.1.x branch at 802195 from trunk.
> 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: 1.1.1, 1.2.0, 1.3.0
>
> Attachments: merge-detached.patch, merge-testcases.patch,
> openjpa-235-break-nullable-070716.patch, openjpa-235-break-nullable.patch,
> openjpa-235-delete-cascade.patch, openjpa-235-test.jar,
> openjpa-235-test1.jar, openjpa-235-test2.zip, openjpa.patch, openjpa.patch,
> 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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