On 2018-04-30 16:07:48 -0700, Peter Geoghegan wrote: > On Mon, Apr 30, 2018 at 4:03 PM, Andres Freund <and...@anarazel.de> wrote: > >> Is this a problem in practice, though? I don't remember seeing any reports > >> of the fsync queue filling up, after we got the code to compact it. I don't > >> know if anyone has been looking for that, so that might also explain the > >> absence of reports, though. > > > > It's probably hard to diagnose that as the origin of slow IO from the > > outside. It's not exactly easy to diagnose that even if you know what's > > going on. > > True, but has anyone ever actually observed a non-zero > pg_stat_bgwriter.buffers_backend_fsync in the wild after the > compaction queue stuff was added/backpatched?
Yes. Greetings, Andres Freund
