On Thu, Jan 9, 2020 at 7:43 AM Fujii Masao <masao.fu...@gmail.com> wrote: > > On Wed, Dec 25, 2019 at 11:11 PM Julien Rouhaud <rjuju...@gmail.com> wrote: > > > > On Wed, Dec 25, 2019 at 2:01 PM Fujii Masao <masao.fu...@gmail.com> wrote: > > > > > > Hi, > > > > > > I'd like to propose to add pg_file_sync() function into contrib/adminpack. > > > This function fsyncs the specified file or directory named by its > > > argument. > > > IMO this is useful, for example, when you want to fsync the file that > > > pg_file_write() writes out or that COPY TO exports the data into, > > > for durability. Thought? > > > > +1, that seems like a useful wrapper. Looking at existing functions, > > I see that there's a pg_file_rename() in adminpack, but it doesn't use > > durable_rename nor does it try to perform any fsync. Same for > > pg_file_unlink vs. durable_unlink. It's probably worth fixing that at > > the same time? > > I don't think that's a bug. I'm not sure if every users of those functions > need durable rename and unlink at the expense of performance. > So IMO it's better to add new argument like "durable" to those functions > and durable_rename or _unlink is used only if it's true.
It's probably a POLA violation. I'm pretty sure that most people using those functions would expect that a successful call to pg_file_unlink() mean that the file cannot raise from the dead even with certain unlikely circumstances, at least I'd expect so. If performance is a problem here, I'd rather have a new wrapper with a sync flag that defaults to true so it's possible to disable it if needed instead of calling a different function. That being said, I agree with Arthur, it should be handled in a different patch.
