Actually what I'm describing is exactly the opposite: because I know the limitations of the disk, if I would have to write custom code to solve my problem, I wo

Actually what I'm describing is exactly the opposite: because I know the limitations of the disk, if I would have to write custom code to solve my problem, I would easily be able to outperform the database. Naturally that has many other issues that still makes me choose a database, like basically all of ACID, but still it is disheartening to know that fundamentally the operation can be done an order of magnitude faster than what you're seeing, and improving the situation means understanding how the DB maps its operations to the disk, and how that produces limitations. So in fact it is the lack of knowledge of the DB, not disk, that causes the problem. Apparently at this scope, the DB is a leaky abstraction.