Re: [HACKERS] A Better External Sort?

On Thu, Oct 06, 2005 at 03:57:38PM -0400, Tom Lane wrote:
> Martijn van Oosterhout <kleptog(at)svana(dot)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 ...

The problem kernels would be Linux 2.0, which I very much doubt is going
to be present in to-be-deployed database servers.

Unless someone runs glibc on top of some other kernel, I guess. Is this
a common scenario? I've never seen it.

--
Alvaro Herrera http://www.amazon.com/gp/registry/DXLWNGRJD34
Oh, oh, las chicas galacianas, lo harán por las perlas,
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