Relative to other kinds of software I use, databases I picture as steam engines, or reactors... The seemingly-constant tuning, indexing, manual analysis and (in the case of PostgreSQL) "vacuuming" remind me of the picture of the engineer crawling endlessly over their machines, turning that knob, tweaking that setting, clearing up that spill when there's time.

It's easy to see how it becomes a full-time job just to maintain these machines.