Re: Single client performance on trivial SELECTs

On Thu, Apr 14, 2011 at 05:10:41PM -0400, Tom Lane wrote:
> Noah Misch <noah@leadboat.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.

Do you have any details, like when mysql did this?  With a quick look, I'm
failing to find confirmation that mysql ever did use gperf.  (Drizzle has
replaced the mysql homegrown scheme with gperf, apparently in 2009, though.)