Aleksandr Kopilov created ARROW-10508:
-----------------------------------------
Summary: [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: 2.0.0, 1.0.0
Reporter: Aleksandr Kopilov
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. Example to reproduce
[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")
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
