From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Peter Eisentraut <peter_e(at)gmx(dot)net>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Allowing WAL fsync to be done via O_SYNC |
Date: | 2001-03-15 20:46:20 |
Message-ID: | 200103152046.PAA18820@candle.pha.pa.us |
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Lists: | pgsql-hackers |
> 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
+ If your life is a hard drive, | 830 Blythe Avenue
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