> One last concern is the size stored on the disk because UTF-8 supports four bytes per character. But since UTF-8 is a variable-width character encoding, it on

> One last concern is the size stored on the disk because UTF-8 supports four bytes per character. But since UTF-8 is a variable-width character encoding, it only uses as many bytes as needed. For example, the first 128 characters like ASCII only use one byte I'm not sure this is true if you use CHAR instead of VARCHAR. Moreover if I'm not misremembering indexes still store the full fixed size 3 or 4 byte representation and index size might matter. However, I'll still use mb4 to avoid the fun times other have already described in the comments