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)