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https://issues.apache.org/jira/browse/ARROW-6420?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Liya Fan closed ARROW-6420.
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Resolution: Later
> [Java] Improve the performance of UnionVector when getting underlying vectors
> -----------------------------------------------------------------------------
>
> Key: ARROW-6420
> URL: https://issues.apache.org/jira/browse/ARROW-6420
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Java
> Reporter: Liya Fan
> Assignee: Liya Fan
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 3h
> Remaining Estimate: 0h
>
> Getting the underlying vector is a frequent opertation for UnionVector. It
> relies on this operation to get/set data at each index.
> The current implementation is inefficient. In particular, it first gets the
> minor type at the given index, and then compares it against all possible
> minor types in a switch statment, until a match is found.
> We improve the performance by storing the internal vectors in an array, whose
> index is the ordinal of the minor type. So given a minor type, its
> corresponding underlying vector can be obtained in O(1) time.
> It should be noted that this technique is also applicable to UnionReader and
> UnionWriter, and support for UnionReader is already implemented.
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