MySQL supports replicating to a slave that is one release higher. This allows us to easily upgrade our MySQL setup to a new version, by promoting the slave and pointing the application to it. However, though unsupported, there are times when the MySQL version of slave deployed is one release lower. In this scenario, if your application has been performing much better on an older version of MySQL, you would like to have a convenient option to downgrade. You can simply promote the slave to get the old performance back.
The MySQL manual says that ROW based
replication can be used to replicate to a lower version, provided
that no DDLs replicated are incompatible with the slave. One such
incompatible command is ALTER USER
which is a new
feature in MySQL 5.7 and not available on 5.6. :
ALTER USER …[Read more]