> people wildly underestimate the os page cache and modern nvme drives

And worse, overestimate how safe is their data!

All this fancy thing about not using a RDBMS could had been true only if the APIs and actual implementation across ALL the IO path were robust and RELIABLE.

But is not!

EVERY LAYER LIES

ALL of them

ALL OF TIME

That is why the biggest reason building a real database (whatever the flavor) is that there is no way to avoid pay performance taxes all over the place because you can't believe the IO and having a (single | some files) getting hammered over and over make this painfully obvious.

One of the most sobering experiences is that you write your IO with all the care in the world, let the (your brand new) DB run for hours, on good, great, hardware, and in less than a week you will find that that breaks in funny ways.

P.D: Was part of a team doing a db