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Posted to jira@arrow.apache.org by "Liya Fan (Jira)" <ji...@apache.org> on 2020/11/19 08:29:00 UTC
[jira] [Resolved] (ARROW-10508) [Java] Allow FixedSizeListVector to
have empty children
[ https://issues.apache.org/jira/browse/ARROW-10508?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Liya Fan resolved ARROW-10508.
------------------------------
Fix Version/s: 3.0.0
Resolution: Fixed
Issue resolved by pull request 8605
[https://github.com/apache/arrow/pull/8605]
> [Java] Allow FixedSizeListVector to have empty children
> -------------------------------------------------------
>
> Key: ARROW-10508
> URL: https://issues.apache.org/jira/browse/ARROW-10508
> Project: Apache Arrow
> Issue Type: Bug
> Affects Versions: 1.0.0, 2.0.0
> Reporter: Aleksandr Kopilov
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.0.0
>
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> h3. General problem
> FixedSizeListVector was designed to hold a list of lists with data (filled rectangle matrix) but in real life we can have list of empty lists (zero-width matrix). Java implementation of FixedSizeListVector does not allow to create (and read) such list. But in [specification|http://arrow.apache.org/docs/format/Columnar.html#fixed-size-list-layout] there is no any restriction that listSize can not be zero. Also zero-width matrix can be successfully created by C++ implementation. Java fails on reading it. The most problem is that entire table (VectorSchemaRoot) can not be read if we have at least one FixedSizeListVector.listSize==0 field.
> h3. Expected behavior
> * Read zero-width matrix (FixedSizeListVector with listSize==0) written by C++ as zero-width matrix.
> * Read any field from the correct table (written and readable by C++)
> h3. Actual behavior
> * java.lang.IllegalArgumentException: list size must be positive at org.apache.arrow.util.Preconditions.checkArgument(Preconditions.java:136)
> * Filled vectors can not be read if at least one fixed list size is 0
> h3. Examples to reproduce
> h4. Reproduce on creating
> Add
> {{FixedSizeListVector.empty("ZeroWidthMatrix", 0, new RootAllocator());}}
> line of code anywhere
> h4. Reproduce on reading
> [https://github.com/Kopilov/Arrow_FixedSizeListVector_ZeroWidth] repository contains C++ and Java code with GitHub Action workflow that reproduces Actual behavior.
> Here are some logs: [https://github.com/Kopilov/Arrow_FixedSizeListVector_ZeroWidth/runs/1363206662] (look "Run C++ example", "Build and run Java example")
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