Re: seq scan cache vs. index cache smackdown

Merlin Moncure wrote:
>
> readv and writev are in the single unix spec...and yes ...
>
> On some systems they might just be implemented as a loop inside the
> library, or even as a macro.

You sure?

Requirements like this:
  http://www.opengroup.org/onlinepubs/007908799/xsh/write.html
  "Write requests of {PIPE_BUF} bytes or less will not be
   interleaved with data from other processes doing writes
   on the same pipe."
make me think that it couldn't be just a macro; and if it
were a loop in the library it seems it'd still have to
make sure it's done with a single write system call.

(yeah, I know that requirement is just for pipes; and I
suppose they could write a loop for normal files and a
different special case for pipes; but I'd be surprised).