Re: fsync vs open_sync

pgsql@mohawksoft.com writes:
> I did a little test on the various options of fsync.

There were considerably more extensive tests back when we created the
different WAL options, and the conclusions seemed to be that the best
choice is platform-dependent and also usage-dependent.  (In particular,
it makes a huge difference whether WAL has its own drive or not.)

I don't really recall why open_sync didn't end up among the set of
choices considered for the default setting.  It may be that we need to
reconsider based on the behavior of newer Linux versions ...

In any case, comparing open_sync to fsync is irrelevant, seeing that
the current default choice on Linux is fdatasync.  What you ought to
be telling us about is the performance relative to that.
        regards, tom lane