[jira] [Updated] (ARROW-10508) [Java] Allow FixedSizeListVector to have empty children

["Jorge Leitão (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-10508?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jorge Leitão updated ARROW-10508:
---------------------------------
    Component/s: Java

> [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
>          Components: Java
>    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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