Maybe one of the more "obscure" operations when dealing with replica lag, or, in general, when one needs to control writes to the database, is the Rate limit. It's also lately one of the most popular conversations around the community.
But what is it? In plain words: holding up queries for a while, giving air to the replicas to breath and catch up. Something similar to the Galera's Flow Control mechanism, although flow control, when it kicks in, stops all the writes while the nodes catch up. With a throttle no write is stopped, just delayed.
Use MySQL Without a Password (And Still Be Secure)
Some say that the best password is the one you don’t have to remember. That’s possible with MySQL, thanks to the auth_socket plugin and its MariaDB version unix_socket.
Neither of these plugins is new, but while reviewing what’s new with MariaDB 10.4, I saw that the unix_socket now comes installed by default and is one of the authentication methods (one of them, because, in MariaDB 10.4, a single user can have more than one authentication plugin, as explained in the Authentication from MariaDB 10.4 document).