Bruce Momjian <pgman@candle.pha.pa.us> writes:
> _That_ is an excellent point. However, do we know at the time we open
> the file descriptor if we will be doing this?
We'd have to say on a per-read basis whether we want O_DIRECT or not,
and fd.c would need to provide a suitable file descriptor.
> What about cache
> coherency problems with other backends not opening with O_DIRECT?
If O_DIRECT introduces cache coherency problems against other processes
not using O_DIRECT then the whole idea is a nonstarter, but I can't
imagine any kernel hackers would have been stupid enough to allow that
to happen ...
regards, tom lane