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https://issues.apache.org/jira/browse/OPENJPA-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vermeulen updated OPENJPA-2246:
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Attachment: openjpalazyeagerfetchplan.zip
Added a complete test case (build with Maven) which shows this bug.
> when using fetchplans a different entitymanager may incorrectly eagerly fetch
> a lazy association
> ------------------------------------------------------------------------------------------------
>
> Key: OPENJPA-2246
> URL: https://issues.apache.org/jira/browse/OPENJPA-2246
> Project: OpenJPA
> Issue Type: Bug
> Components: jpa, performance
> Affects Versions: 2.1.1, 2.2.0
> Reporter: Vermeulen
> Attachments: openjpalazyeagerfetchplan.zip
>
>
> Setting a FetchPlan on an entitymanager which loads a certain @OneToMany
> field that is marked as lazy and cascade all, can result in a different
> entityManager (created by the same factory) to eagerly fetch this field, even
> if the field is not in the fetchplan of this different entityManager.
> I found two situations where this occurs (each step uses a different
> entityManager with a transaction):
> 1.
> * em.merge a new entity (and cascaded related entity) with fetchgroup added
> * find entity with no fetchgroup added
> -> the lazy-fetched field is incorrectly loaded
> 2.
> * em.persist a new entity (and cascaded related entity) with NO fetchgroup
> added
> * find entity with fetchgroup added
> * find entity with NO fetchgroup added
> -> the lazy-fetched field is incorrectly loaded
> The weird thing is that persist and merge behave inconsistently - isn't that
> great, an inconsistency within an inconsistency? - because switching
> persist/merge results in the following situations that work as expected:
> 1.
> * em.persist a new entity (and cascaded related entity) with fetchgroup added
> * find entity with no fetchgroup added
> -> the lazy-fetched field is a null reference (expected)
> 2.
> * em.merge a new entity (and cascaded related entity) with NO fetchgroup
> added
> * find entity with fetchgroup added
> * find entity with NO fetchgroup added
> -> the lazy-fetched field is a null reference (expected)
> Checking the trace and generated SQL confirms that the field that should not
> be fetched is in fact fetched.
> I think this is a bug because this is both inefficient and is inconsistent
> because I wish my data access to behave predictably.
> Note that turning on <property name="openjpa.DetachState"
> value="fetch-groups" /> in persistence.xml solves the issues but internally
> OpenJPA still performs the eager fetch.
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