On Wed, Jun 2, 2021 at 5:20 PM Michael Paquier <mich...@paquier.xyz> wrote: > Note: FreeBSD 13~ has support for copy_file_range(), nice.. Adding > Thomas in CC in case I am missing something.
Yeah, so at least in theory Linux and FreeBSD can now both do tricks like pushing copies down to network filesystems, COW file systems, and (I believe not actually done by anyone yet, could be wrong) SCSI and NVMe devices (they have commands like XCOPY that can copy block ranges directly). I read a few things about all that, and I had a trivial patch to try to use it in the places in the backend where we copy files (like cloning a database with CREATE DATABASE and moving files with ALTER TABLE SET TABLESPACE), but I hadn't got as far as actually trying it on any interesting filesystems or figuring out any really good uses for it. FWIW, here it is: https://github.com/postgres/postgres/compare/master...macdice:copy_file_range The main thing I noticed was that Linux < 5.3 can fail with EXDEV if you cross a filesystem boundary, is that something we need to worry abou there?
