Re: Sync vs. fsync during checkpoint

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

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.

			regards, tom lane