Re: Single client performance on trivial SELECTs

On Thursday 14 April 2011 23:10:41 Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
> > On Thu, Apr 14, 2011 at 11:15:00AM -0700, Robert Haas wrote:
> >> It shouldn't be
> >> terribly difficult to come up with some kind of hash function based
> >> on, say, the first two characters of the keyword that would be a lot
> >> faster than what we're doing now.
> >
> > I'd look at `gperf', which generates code for this from your keyword
> > list.
>
> FWIW, mysql used to use gperf for this purpose, but they've abandoned it
> in favor of some homegrown hashing scheme. I don't know exactly why,
> but I wonder if it was for licensing reasons. gperf itself is GPL, and
> I don't see any disclaimer in the docs saying that its output isn't.
http://lists.gnu.org/archive/html/bug-gnu-utils/2008-08/msg00005.html :

> Thanks for the suggestion; it indeed becomes sort of an FAQ. I've added
>
> this text to the documentation:
> gperf is under GPL, but that does not cause the output produced
> by gperf to be under GPL. The reason is that the output contains
> only small pieces of text that come directly from gperf's source
> code -- only about 7 lines long, too small for being significant --,
> and therefore the output is not a "derivative work" of gperf (in the
> sense of U.S.@: copyright law).

Andres