This is really strange, the fact that is is 255 and not 191. I was part of a discussion about raising the limit of option_name to 255 and they decided there that 191 would be better since the index is only capable of indexing 191 characters. I’ve never noticed that the meta_key field allowed 255, or I have, but I did not think about the fact the the index only works on the first 191 characters.
I find it a little amusing that the length of this db field does not consider the max length of the key.
I used to use this to force the length of the options name field to be longer and not allow WP updates to change it. https://github.com/Hube2/wp-update-prevent-db-changes. I’ll need to look forcing the meta_key field to stay at 191.
Thanks for making me aware of this
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users
Helping others is a great way to earn karma, gain badges and help ACF development!