On Thu, Feb 14, 2019 at 8:11 AM Tom Lane <t...@sss.pgh.pa.us> wrote: > Andres Freund <and...@anarazel.de> writes: > > I was kinda pondering just open coding it. I am not yet convinced that > > my idea of just using an open FD isn't the least bad approach for the > > issue at hand. What precisely is the NFS issue you're concerned about? > > I'm not sure that fsync-on-FD after the rename will work, considering that > the issue here is that somebody might've unlinked the file altogether > before we get to doing the fsync. I don't have a hard time believing that > that might result in a failure report on NFS or similar. Yeah, it's > hypothetical, but the argument that we need a repeat fsync at all seems > equally hypothetical. > > > Right now fsync_fname_ext isn't exposed outside fd.c... > > Mmm. That makes it easier to consider changing its API.
Just to make sure I understand: it's OK for the file not to be there when we try to fsync it by name, because a concurrent checkpoint can remove it, having determined that we don't need it anymore? In other words, we really needed either missing_ok=true semantics, or to use the fd we already had instead of the name? I found 3 examples of this failing with an ERROR (though not turning the BF red, so nobody noticed) before the PANIC patch went in: https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=nightjar&dt=2018-09-10%2020%3A54%3A21&stg=subscription-check 2018-09-10 17:20:09.247 EDT [23287] sub1 ERROR: could not open file "pg_logical/snapshots/0-161D778.snap": No such file or directory 2018-09-10 17:20:09.247 EDT [23285] ERROR: could not receive data from WAL stream: ERROR: could not open file "pg_logical/snapshots/0-161D778.snap": No such file or directory https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=nightjar&dt=2018-08-31%2023%3A25%3A41&stg=subscription-check 2018-08-31 19:52:06.634 EDT [52724] sub1 ERROR: could not open file "pg_logical/snapshots/0-161D718.snap": No such file or directory 2018-08-31 19:52:06.634 EDT [52721] ERROR: could not receive data from WAL stream: ERROR: could not open file "pg_logical/snapshots/0-161D718.snap": No such file or directory https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=nightjar&dt=2018-08-22%2021%3A49%3A18&stg=subscription-check 2018-08-22 18:10:29.422 EDT [44208] sub1 ERROR: could not open file "pg_logical/snapshots/0-161D718.snap": No such file or directory 2018-08-22 18:10:29.422 EDT [44206] ERROR: could not receive data from WAL stream: ERROR: could not open file "pg_logical/snapshots/0-161D718.snap": No such file or directory -- Thomas Munro http://www.enterprisedb.com
