> fsync() is a system call that flushes a file's contents from the
> buffer cache to disk. PG uses it to ensure consistency in the WAL
> files. It is enabled by default. Do NOT disable it unless you know
> exactly what you are doing and are prepared to sacrifice some data
> integrity for performance.
The only issue of data integrity is in the case of an unclean shutdown,
like a power failure or a crash. PG and my OS are reliable enough that I
trust them not to crash, and my hardware has proven itself as well. Of
course, as you point out, if someone doesn't trust their server, they're
taking chances.
That being said, even on other machines with fsync turned off and
unclean shutdowns (power cycles, etc.), I have yet to run into any problem
with PG's consistency, although I certainly cannot guarantee that would be
the case for anyone else!
steve