I think PostgreSQL actually is a bit of an odd one in that it relies on the OS to do proper caching of whatever data is read from disk. It has its own buffers f

I think PostgreSQL actually is a bit of an odd one in that it relies on the OS to do proper caching of whatever data is read from disk. It has its own buffers for various things, but I'm pretty sure it doesn't (yet) implement its own disk cache.