EclipseLink 2.3.0 – same issue on 2.3.2 but stack trace from 2.3.0
Running into an issue where batch fetch and fetch join are not playing nicely with each other. I have a query like
select obj from Parent
left join fetch obj.elementCollection
with hints eclipselink.batch = obj.oneToMany and eclipselink.batch.type = IN.
in the Parent object, there is an @ElementCollection and a @OneToMany, where the @OneToMany is batch-fetched and the @ElementCollection is joined (batch fetch on it instead seemed to have no effect).
It breaks with the below error; changing the batch type from IN to EXISTS makes it work.
java.lang.NullPointerException
at org.eclipse.persistence.mappings.OneToOneMapping.extractBatchKeyFromRow(OneToOneMapping.java:624)
at org.eclipse.persistence.mappings.ForeignReferenceMapping.extractResultFromBatchQuery(ForeignReferenceMapping.java:524)
at org.eclipse.persistence.internal.indirection.NoIndirectionPolicy.valueFromBatchQuery(NoIndirectionPolicy.java:294)
at org.eclipse.persistence.mappings.ForeignReferenceMapping.batchedValueFromRow(ForeignReferenceMapping.java:215)
Any ideas – am I doing something wrong or is this a bug?
Please try the 2.4 release, and log a bug if the error still occurs.
You should be able to batch fetch the element collection as well. If you cannot, please log a bug with a test case.