"All Unix filesystems will ensure the move operation is atomic."
replyThis is false, but most fs will. However, there is a lot of fs calls you have to make that you probably don't know about to make the fs operations atomic.
PS The way you propose is probably the hardest way to do an atomic FS operation. It will have the highest probably of failure and have the longest period of operations and service disruption. There is good reason we move rows one at a time or in batches sized to match OS buffers.
don't forget to fsync the file before the rename! and you also need to fsync the directory after the rename!
replyCorrect, the file must be flushed to disk! I'm so used to libraries handling it that I forgot to mention that.
replyI believe syncing the parent directory is only needed for durability and not atomicity, but if you're using this method you're probably not caring about durability in the first place, because you've designed a system that doesn't let you do durability in a fine-grained way without severe performance loss.