There have been some previous discussions on the mailing about supporting 64-bit lengths for Java ValueVectors (this is what the IPC specification and C++ support). I created a PR [1] that changes all APIs that I could find that take an index to take an "long" instead of an "int" (and similarly change "size/rowcount" APIs).
It is a big change, so I think it is worth discussing if it is something we still want to move forward with. It would be nice to come to a conclusion quickly, ideally in the next few days, to avoid a lot of merge conflicts. The reason I did this work now is the C++ implementation has added support for LargeList, LargeBinary and LargeString arrays and based on prior discussions we need to have similar support in Java before our next release. Support 64-bit indexes means we can have full compatibility and make the most use of the types in Java. Look forward to hearing feedback. Thanks, Micah [1] https://github.com/apache/arrow/pull/5020
