I am always torn on a nullable boolean. I have gone both ways (leave as null or convert to false) depending on what it is representing. In this particular case

I am always torn on a nullable boolean. I have gone both ways (leave as null or convert to false) depending on what it is representing. In this particular case, I agree that you should record the most raw form. Which would be a boolean column of trues and nulls -perfectly handled by parquet.