Re: Allowing WAL fsync to be done via O_SYNC

> Bruce Momjian <pgman@candle.pha.pa.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@candle.pha.pa.us               |  (610)
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