Disk read access access is less and less relevant in normal business application DBs. It is common at the far ends of scalability spectrum: low end where peopl

Disk read access access is less and less relevant in normal business application DBs. It is common at the far ends of scalability spectrum: low end where people use $2 VPS, and high end where big tech can afford to invest a lot in engineering effort to build complex systems that are fine tuned for many levels of memory hierarchy. Most systems can just add memory until data fits. (of course frequently they still don't, and keep doing more expensive things like having many separate copies for different purposes built in various different expensive projects... Sometimes additionally faux justified by using cloud platforms that charge prohitively for memory)