The traditional way to monitor replication in MySQL is the
SHOW SLAVE STATUS command. However as it will be
shown, it has its limitations and in MySQL 5.7 and 8.0 the MySQL
developers have started to implement the information as
Performance Schema tables. This has several advantages including
better monitoring of the replication delay in MySQL 8.0. This
blog discusses why
SHOW SLAVE STATUS should be
replaced with the Performance Schema tables.
The replication setup that will be used for the examples in this blog can be seen in the following figure.