From: | Noah Misch <noah(at)leadboat(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Single client performance on trivial SELECTs |
Date: | 2011-04-15 12:40:46 |
Message-ID: | 20110415124046.GA18609@tornado.leadboat.com |
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Lists: | pgsql-hackers |
On Thu, Apr 14, 2011 at 05:10:41PM -0400, 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.
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.)
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