FORMAT_BYTES(count)

Given a numeric byte count, converts it to human-readable format and
returns a string consisting of a value and a units indicator. The
string contains the number of bytes rounded to 2 decimal places and a
minimum of 3 significant digits. Numbers less than 1024 bytes are
represented as whole numbers and are not rounded.

URL: https://dev.mysql.com/doc/refman/8.0/en/performance-schema-functions.html

