[macdice]

I am not a Windows guy but I (with help) managed to get IOCP working for this in a basic prototype. Will share publicly soon. I also sketched out an IoRing version (if you are interested in helping debug and flesh that out let me know!).

Main learnings: the IOCP version can't do asynchronous flush! Which we want. The IoRing version can! But it can't do scatter/gather AKA vector I/O yet! Which is an essential feature for buffer pool implementation. So actually I am basically waiting for IoRing to add support for that before taking it too seriously (I can see they are working on it because the ops are present in an enum, it's just that the build functions are missing).

So my guess is that in a year or so we should be able to run all PostgreSQL disk I/O through IoRing on Windows. Maybe?

Another complications is that it really wants to be multithreaded (consuming completions for IOs started in another process requires a lot of hoop jumping, I made it work but...) This will resolve itself naturally with ongoing work to make PostgreSQL multithreaded.

The next problem is that IoRing doesn't support sockets! So in future work on async networking (early prototypes exist) we will likely also need IOCP for that part.

[p_ing]

Look into Registered I/O for sockets.