> On x86, and I think every architecture, when you write to a memory mapping that is not already backed by a writable page, the kernel is notified that user code is trying to write. And the kernel needs to fill in the contents of the page, which requires a read if the page isn’t already loaded.

This is very true. Perhaps there wasn't enough context to what the article is describing. The read problem started to occur on database that is subject to constant write workload. Data is flowing in all the time at variable rate. Typically blocks are "hot" and being filled in fully within seconds if not millis.

Zeroing the file is an option to try. QuestDB allocates disk with `posix_fallocate()`, which doesn't have the required flags. We would need to explore `fallocate()`. Thanks.