Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint

[Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>]

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > The trick is to somehow record all files modified since the last
> > checkpoint, and open/fsync/close each one.   My idea is to stat() each
> > file in each directory and compare the modify time to determine if the
> > file has been modified since the last checkpoint.
> 
> This seems a complete non-starter, as stat() generally has at best
> one-second resolution on mod times, even if you assume that the kernel
> keeps mod time fully up-to-date at all times.  In any case, it's
> difficult to believe that stat'ing everything in a database directory
> will be faster than keeping track of it for ourselves.

Yes, we would have to have a slop factor and fsync anything more than
one second before the last checkpoint.  Any ideas on how to record the
modified files without generating tones of output or locking contention?

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