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https://issues.apache.org/jira/browse/OPENJPA-677?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12620858#action_12620858
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Pinaki Poddar commented on OPENJPA-677:
---------------------------------------
The bug is reproducible.
The workaround is to change RegularUsr.admin field from lazily loaded to
eagerly loaded.
The bug seems to be how OpenJPA determines the concrete type of a relation from
the record row data and the discrimnator column. In this case
mysql> select * from computeruser;
---------------------------------------
| oid DTYPE ADMIN_OID
---------------------------------------
101 admin NULL
102 user 101
---------------------------------------
During load of row 102, i.e. '102 'user' 101', OpenJPA tries to store a FK
(pointing to Admin) for the row 102 (which represents a RegularUser).
However, because the row's discrimnator value is 'user', OpenJPA wrongly
assumes that 101 is identifier for RegularUser and that is the oid is store
intermediately in RegularUser-102's admin field.
Later when OpenJPA reads the full row 101, (say for find()) it does construct a
Admin-102 instance but that other identifier has created a different Admin
object and hence the error.
Eager loading gets rid of the problem because then both the rows are read in a
single query and the ambiguity of discriminator value does not arise.
> Single Table Inheritance Strategy causes entity identity issues
> ---------------------------------------------------------------
>
> Key: OPENJPA-677
> URL: https://issues.apache.org/jira/browse/OPENJPA-677
> Project: OpenJPA
> Issue Type: Bug
> Affects Versions: 1.1.0, 1.1.1, 1.2.0, 1.2.1, 1.3.0
> Environment: IBM Java 1.5
> Reporter: Przemek Koprowski
> Assignee: Pinaki Poddar
> Attachments: TestJPAIdentityWhenSingleTable.zip
>
>
> Entity objects that are pulled out from the database using bean methods
> (get*()) are not the same objects that are pulled out using using other
> methods(find(), getReference()).
> This occurs only when using Single Table Inheritance.
> This works on 0.9.7, in other versions Exception is thrown
> (https://issues.apache.org/jira/browse/OPENJPA-494) , in latest version from
> trunk test fails.
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