MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
The following statements support use of the
CURRENT_USER() function to take
the place of the name of, and possibly the host for, an affected
user or a definer:
When binary logging is enabled and
CURRENT_USER() or
CURRENT_USER is used as the
definer in any of these statements, MySQL Server ensures that
the statement is applied to the same user on both the source and
the replica when the statement is replicated. In some cases,
such as statements that change passwords, the function reference
is expanded before it is written to the binary log, so that the
statement includes the user name. For all other cases, the name
of the current user on the source is replicated to the replica
as metadata, and the replica applies the statement to the
current user named in the metadata, rather than to the current
user on the replica.