Hey folks, I have a (relatively) small change here <https://github.com/apache/iceberg/pull/15084> to add the capability to undelete columns, and a corresponding Spark function. I was hoping to get some feedback from the list on this improvement.
I'll note that the spec specifically says column undeletion is allowed, but only for these two situations: "Field deletion cannot be rolled back unless the field was nullable or if the current snapshot has not changed". The PR I've proposed allows for undeleting of non-nullable columns, but forces them to be optional upon rollback. I believe this is a reasonable tradeoff. Looking forward to any feedback on the change. Frank
