Re: [PERFORM] A Better External Sort?

Martijn van Oosterhout <kleptog@svana.org> writes:
> Indeed, one of the things on my list is to remove all the lseeks in
> favour of pread. Halving the number of kernel calls has got to be worth
> something right? Portability is an issue ofcourse...

Being sure that it's not a pessimization is another issue.  I note that
glibc will emulate these functions if the kernel doesn't have them;
which means you could be replacing one kernel call with three.

And I don't think autoconf has any way to determine whether a libc
function represents a native kernel call or not ...

            regards, tom lane