Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)

Andres Freund <andres@anarazel.de> writes:
> This speeds up CREATE DATABASE from ~9 seconds to something around 0.8s on my
> laptop.  Still slower than with fsync off (~0.25) but quite a worthy
> improvement.

I can't help wondering whether that's real or some kind of
platform-specific artifact.  I get numbers more like 3.5s (fsync off)
vs 4.5s (fsync on) on a machine where I believe the disks aren't lying
about write-complete.  It makes sense that an fsync at the end would be
a little bit faster, because it would give the kernel some additional
freedom in scheduling the required I/O, but it isn't cutting the total
I/O required at all.  So I find it really hard to believe a 10x speedup.

            regards, tom lane