I second this idea. It will definitely help everyone particularly users posting in local forums in their own language as different language use different amount of bytes (as theymos enlightened us). A good option would be,as suggested, to add a Read More option appear after a certain characters limit so it doesn't look too long if that post is quoted by someone
It's not so simple as the character limit in mysql, the database server that the forum presumably uses, is 65,535 bytes for a VARCHAR:
https://dev.mysql.com/doc/refman/5.7/en/char.htmlFixing this would mean some major changes to the forums software, which likely won't happen in this software, but the new forum software that is being developed uses a different database server which may not have this limit. So something like you propose is much easier to do with the new forum software.