Which will be pretty irritating for the end user as they will not know what is wrong. Which can be in any place from mildly irritating to that cannot ever happen and we resign from your services depending on what your application does.
Rarely, and even when I do then I do not treat it as “this limit will never change” as something like that is highly improbable. Twitter changed character limit, Git will change character limit, etc. Setting hard limit because right now you think that it will be set in stone isn’t wise. So application-side check is all you need, you do not need to impose limit on the DB as well.
Yes, that is big. But if you want to save 342 copies of whole War and Peace in one text field then I would expect bigger problems before it would even hit the DB.
