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Posted to dev@openjpa.apache.org by "Vermeulen (JIRA)" <ji...@apache.org> on 2012/08/03 16:14:03 UTC
[jira] [Updated] (OPENJPA-2246) when using fetchplans a different
entitymanager may incorrectly eagerly fetch a lazy association
[ https://issues.apache.org/jira/browse/OPENJPA-2246?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Vermeulen updated OPENJPA-2246:
-------------------------------
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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