On Mon, 2007-09-10 at 22:44 +0100, Gregory Stark wrote:
> What I don't understand is the bit about "until Postgres gets AIO + the
> ability to post multiple concurrent IOs on index probes". Even with AIO your
> seek times are not going to be improved by wide raid stripes. And you can't
> possibly find the page at level n+1 before you've looked at the page at level
> n. Do you mean to be able to probe multiple index keys simultaneously? How
> does that work out?
>
I think he's referring to mirrors, in which there are multiple spindles
that can return a requested block. That could mitigate random I/O, if
the I/O is asynchronous and something intelligent (OS or controller) can
schedule it.
Regards,
Jeff Davis