Re: Allowing WAL fsync to be done via O_SYNC

I'd actually vote for it to remain for a release or two or more, as
we get more experience with stuff, the defaults may be different for
different workloads.

LER
--
Larry Rosenman
http://www.lerctr.org/~ler/
Phone: +1 972 414 9812
E-Mail: ler(at)lerctr(dot)org
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>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 3/15/01, 2:46:20 PM, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> wrote
regarding Re: [HACKERS] Allowing WAL fsync to be done via O_SYNC:

> > Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > > I later read Vadim's comment that fsync() of two blocks may be faster
> > > than two O_* writes, so I am now confused about the proper solution.
> > > However, I think we need to pick one and make it invisible to the user.
> > > Perhaps a compiler/config.h flag for testing would be a good solution.
> >
> > I believe that we don't know enough yet to nail down a hard-wired
> > decision. Vadim's idea of preferring O_DSYNC if it appears to be
> > different from O_SYNC is a good first cut, but I think we'd better make
> > it possible to override that, at least for testing purposes.
> >
> > So I think it should be configurable at *some* level. I don't much care
> > whether it's a config.h entry or a GUC variable.
> >
> > But consider this: we'll be more likely to get some feedback from the
> > field (allowing us to refine the policy in future releases) if it is a
> > GUC variable. Not many people will build two versions of the software,
> > but people might take the trouble to play with a run-time configuration
> > setting.

> Yes, I can imagine. Can we remove it once we know the answer?

> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
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