Github user twalthr commented on the issue: https://github.com/apache/flink/pull/5613 @Xpray yes that might be necessary as well. I think this code does not solve all problems but the most urgent ones. It still fails if expressions in a field become too large or the unboxing. Or even the class itself. There are many limitation that could be reached: https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.9 Do you have use cases where you reach the limits with my current implementation?