The sys schema was created to make it easier to use
the Performance Schema. This included several functions, for
example to convert the picoseconds used by the Performance Schema
into human readable strings. In MySQL 8.0.16, three of these
functions have been implemented as native functions in MySQL
Server.
Why do away with the sys schema functions? There are
two reasons: performance and ease of use. The native functions
are written in C++ like the rest of the server whereas the
sys schema functions were written as stored
functions. Function written in C++ are inherently faster than
stored functions. Additionally, that the functions are native
means you no longer need to prefix them with sys. to
tell MySQL where …
