Re: Allowing WAL fsync to be done via O_SYNC

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> > Based on the tests we did last week, it seems clear than on many
> > platforms it's a win to sync the WAL log by writing it with open()
> > option O_SYNC (or O_DSYNC where available) rather than
> > issuing explicit fsync() (resp. fdatasync()) calls.
>
> I don't remember big difference in using fsync or O_SYNC in tfsync
> tests. Both depend on block size and keeping in mind that fsync
> allows us syncing after writing *multiple* blocks I would either
> use fsync as default or don't deal with O_SYNC at all.

I see what you are saying. That the OS may be faster at fsync'ing two
blocks in one operation rather than doing to O_SYNC operations.

Seems we should just pick a default and leave the rest for a later
release. Marc wants RC1 tomorrow, I think.

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