How much is it possible to know about the systems? The app I work on now uses MariaDB (multiple versions at this point), postgres, Cassandra, and InfluxDB. Those are just the databases I can recall offhand; there may be others and there were others before my time at the company. And those are just the databases. I’m also responsible for hardware, networking, cloud infrastructure to include IaaS and container orchestration plus tons of services. Say it I should read the docs on all that is like a cruel joke. Not only are there not enough hours in the day, I doubt there are enough years in my life to imagine such a task. And it would be Sisyphean anyway because at any given moment one of them will make a “minor” update that breaks functionality and a bit of my knowledge will be useless. Welcome to the world of postmodern system administration; I guess we call it DevOps or SRE now or something; even that’s a philosophical debate these days.