Finding metrics that matter in MySQL.
Having now transitioned into a role that requires MySQL knowledge instead of Postgres knowledge, it is time to learn some new queries.
Total database size
Free Space here is an interesting notion. This "free space" is the space available inside the engine's (InnoDB or MyISAM) table spaces. This is not a reflection of total available disk space.
Top 20 tables by size
If your database is small (relatively few tables), you can take out the limit clause and see all tables.