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https://issues.apache.org/jira/browse/ARROW-399?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17657433#comment-17657433
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Rok Mihevc commented on ARROW-399:
----------------------------------
This issue has been migrated to [issue
#16027|https://github.com/apache/arrow/issues/16027] on GitHub. Please see the
[migration documentation|https://github.com/apache/arrow/issues/14542] for
further details.
> [Java] ListVector.loadFieldBuffers ignores the ArrowFieldNode length metadata
> -----------------------------------------------------------------------------
>
> Key: ARROW-399
> URL: https://issues.apache.org/jira/browse/ARROW-399
> Project: Apache Arrow
> Issue Type: Bug
> Components: Java
> Reporter: Wes McKinney
> Assignee: Julien Le Dem
> Priority: Blocker
> Fix For: 0.2.0
>
> Attachments: list_error.json
>
>
> Discovered this during integration testing. Because Arrow-C++ writes buffers
> padded to 64 bytes, they may appear larger to the Java library than they need
> to be. In ListVector.loadFieldBuffers, the ArrowFieldNode is never used:
> {code:language=java}
> @Override
> public void loadFieldBuffers(ArrowFieldNode fieldNode, List<ArrowBuf>
> ownBuffers) {
> BaseDataValueVector.load(getFieldInnerVectors(), ownBuffers);
> }
> {code}
> The value count of the resulting ListVector is thus inferred from the size of
> the offsets buffer. In the case of a length-7 vector in C++, the size of the
> offsets buffer is exactly 64 bytes (padding for SIMD) -- Java infers from 64
> bytes that the value count is 15 (64 / 4 - 1), and the integration test fails.
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