The article explains why they want to avoid this option:

> Starting at version 14, PostgreSQL supports generated columns - these are columns that are automatically populated with an expression when we insert the row. Sounds exactly like what we need but there is a caveat - the result of the expression is materialized - this means additional storage, which is what we were trying to save in the first place!

Thanks, missed that part. I would still be interested in knowing how much additional storage that adds, if the OP is interested in updating the article.