MySQL 8.4 Release Notes
The BLACKHOLE storage engine
accepts data but discards it and does not store it. When
performing binary logging, all inserts to such tables are always
logged, regardless of the logging format in use. Updates and
deletes are handled differently depending on whether statement
based or row based logging is in use. With the statement based
logging format, all statements affecting
BLACKHOLE tables are logged, but their
effects ignored. When using row-based logging, updates and
deletes to such tables are simply skipped—they are not
written to the binary log. A warning is logged whenever this
occurs.
For this reason we recommend when you replicate to tables using
the BLACKHOLE storage engine that
you have the binlog_format
server variable set to STATEMENT, and not to
either ROW or MIXED.