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https://issues.apache.org/jira/browse/OPENJPA-1896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12973548#action_12973548
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Cefn Hoile commented on OPENJPA-1896:
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Sorry to let you down, Rick. I can't easily verify the patch. I no longer have
a codebase incorporating OpenJPA as I switched to Hibernate. This bug just
seemed too major to me, and made me wonder what else I would discover if I
relied on OpenJPA.
I appreciate the work you've put in, and I hope it helps supporting other
OpenJPA users who want to use POJOs with natural keys as the project gets wider
adoption. I like a lot of the features which OpenJPA adds on top of JPA, but
standards conformance is more important for the future of our project
(switching easily between persistence frameworks).
Focusing just on JPA functionality I found the OpenJPA enhancement process
really complex and likely to introduce issues in deployment, (Hibernate just
worked). However, this merge bug was the clincher because of the domain we're
working on.
> OpenJPA cannot store POJOs if a corresponding record already exists
> -------------------------------------------------------------------
>
> Key: OPENJPA-1896
> URL: https://issues.apache.org/jira/browse/OPENJPA-1896
> Project: OpenJPA
> Issue Type: Bug
> Affects Versions: 2.0.1
> Environment: Eclipse, Sun Java 1.6, Ubuntu Lucid, Guice
> JPAPersistModule, build-time enhance.xml
> Reporter: Cefn Hoile
> Assignee: Rick Curtis
> Attachments: openjpa-1896.jar
>
>
> If a POJO is created using a java constructor, merge() cannot store the newly
> constructed object's data if this means updating a pre-existing record with a
> matching identity.
> This is a major bug since it means applications where the objects have a
> natural key cannot use OpenJPA. In my case the example was a filesystem; each
> crawl of the filesystem generates its own data objects with file path as the
> natural key. These objects then need to be stored into the database. Previous
> crawls may have encountered the same files, and the merge operation should
> cause the latest data from the POJO to be stored in the pre-existing record.
> Instead, any attempt to execute either merge() or persist() on an
> independently constructed object with a matching record identity in the
> database triggers the same error in the database layer, since OpenJPA
> attempts to execute an insert for a pre-existing primary key, throwing...
> org.apache.openjpa.lib.jdbc.ReportingSQLException: ERROR: duplicate key value
> violates unique constraint "file_pkey" {prepstmnt 32879825 INSERT INTO file
> (locationString, location, version, folder) VALUES (?, ?, ?, ?) [params=?,
> ?, ?, ?]} [code=0, state=23505]
> From discussion with Rick Curtis on the [email protected] list, this
> is because the version field on a POJO which is unmanaged is not yet set.
> An ASSUMPTION seems to be made that no such record exists in the database
> already since it wasn't loaded from the database in the first place, so a
> persist is attempted. Instead, I recommend the database is QUERIED TO FIND
> OUT if such a record already exists, and the version field is set
> correspondingly before attempting the merge()
> Here is the corresponding thread containing Ricks comments and links to an
> example in Github which can recreate the problem.
> http://bit.ly/hfPjTI
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