Comment by SQLite

Yes. And there is code in the SQLite source tree (currently on a branch) that supports OFD locks. The problem we have is that SQLite is so widely deployed and is in so many systems and on so many platforms, that we have to continue to support Posix Advisory Locks (PAL) for the foreseeable future, for compatibility. It will be great if someday we can remove the PAL code. But for now, it has to stay in the tree.