[madhusudhan000]

Author here.

> I was surprised to learn Postgres doesn't use direct read/write (O_DIRECT) to bypass kernel caches.

It is more related to the database being platform neutral. The community is very sensitive to putting in performance improvement/hacks which applies only to certain systems. There was a discussion back then - https://www.postgresql.org/message-id/50E4AAB1.9040902@optio.... There were several more, you can search around the mail archives, but the general tendency is not to put changes which is not universally applicable to all platforms.

With that said, a lot is changing, as their community grows we can expect optimizations like these.

> The article doesn't go into the details, but maybe someone can point me to some resources that explain the benefits of this double cache layer?

The article was already a bit long so I didn't go into much details. Perhaps ill write on it in another article.

[dullgiulio]

Thank you. And yes, please do write more about such things, it would be very interesting read.