Backend fsyncs are theoretically still possible after the fsync request queue compaction patch (which was subsequently back-patched to all supported release branches). However, I'm reasonably confident that that patch was so effective as to make a backend fsync all but impossible. As such, it seems like the buffers_backend_fsync column in the pg_stat_bgwriter view is more or less obsolete.
I suggest removing it for 9.5, and instead logging individual occurrences of backend fsync requests within ForwardFsyncRequest(). It seems fair to treat that as an anomaly to draw particular attention to. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
