Re: O_DIRECT in freebsd

"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
> The reason I mention it is that Postgres already supports O_DIRECT I think
> on some other platforms (for whatever reason).

[ sounds of grepping... ]  No.  The only occurrence of O_DIRECT in the
source tree is in TODO:

* Consider use of open/fcntl(O_DIRECT) to minimize OS caching

I personally disagree with this TODO item for the same reason Sean
cited: Postgres is designed and tuned to rely on OS-level disk caching,
and bypassing that cache is far more likely to hurt our performance than
help it.

However, if someone wants to do some experimentation with O_DIRECT, I'd
be as interested as anyone to find out what happens...
        regards, tom lane